Patent Application
20230100663
A luminophore and a process for producing a luminophore are specified. Additionally specified is a radiation-emitting component.
One problem addressed is that of specifying a luminophore having elevated efficiency. Further problems addressed are a process for producing a luminophore having elevated efficiency, and a radiation-emitting component having elevated efficiency.
A luminophore is specified. In at least one embodiment, the luminophore has the general formula AzEeX6:RE where
Here and hereinafter, luminophores are described by empirical formulae. The elements listed in empirical formulae are in charged form. Here and hereinafter, elements or atoms in relation to the empirical formula of the luminophores thus mean ions in the form of cations and anions, even if this is not stated explicitly. This is also true of element symbols if these are specified without their charge for the sake of clarity.
It is possible in the empirical formula specified that the luminophore includes further elements, for example in the form of impurities. Collectively, these impurities comprise not more than 5 mol %, especially not more than 1 permille, especially not more than 100 ppm (parts per million), preferably not more than 10 ppm.
In at least one embodiment, the luminophore comprises a mixture. The mixture comprises the general formula AzEeX6:RE or consists of the general formula AzEeX6:RE. Further constituents of the mixture may, for example, the reactants that have not reacted in the course of preparation of the luminophore, impurities and/or secondary phases that are formed in the reaction.
The term “valency” in relation to a particular element in the present context means how many elements having a single opposite charge are required in a chemical compound to achieve balancing of the charge. Thus, the term “valency” encompasses the charge of the element.
Elements having a valency of two are referred to as divalent elements. Divalent elements are frequently doubly positively charged in chemical compounds and have a charge of +2. Balancing of the charge in a chemical compound may take place, for example, by means of two further elements that are each singly negatively charged, or one element which is doubly negatively charged. Divalent elements in the present context are generally selected from the group formed by alkaline earth metals and elements of the transition groups.
Tetravalent elements are elements having a valency of four. Tetravalent elements are frequently quadruply positively charged in chemical compounds and have a charge of +4. Balancing of the charge in a chemical compound may take place, for example, by means of one element which is quadruply negatively charged, by means of two elements that are doubly negatively charged, or four elements that are each singly negatively charged. Tetravalent elements in relation to E in the present context are generally selected from the group formed by silicon, germanium, tin, lead, titanium, zirconium and hafnium.
Monovalent elements are elements having a valency of one. Monovalent elements in chemical compounds may be singly negatively charged and have a charge of −1. The monovalent elements serve to balance the charge of the cations. Monovalent elements in the present context are generally selected from the group formed by the halogens. The present luminophore had a total of six monovalent anions.
The present luminophore may be in outwardly uncharged form. This means that there may be outwardly complete balancing of charge between positive and negative charges in the luminophore. By contrast, it is also possible that the luminophore formally does not have complete balancing of charge to a minor degree.
Such a luminophore can convert electromagnetic radiation of a particular wavelength or particular wavelength range, referred to hereinafter as primary radiation, to electromagnetic radiation of a second wavelength or second wavelength range, referred to hereinafter as secondary radiation. The conversion of primary radiation to secondary radiation is also referred to as wavelength conversion. In particular, wavelength conversion involves absorption of primary radiation by a wavelength-converting element that contains a luminophore, conversion thereof to secondary radiation by electronic processes at the atomic and/or molecular level, and emission again. Primary and secondary radiation thus have at least partly different wavelength ranges, with secondary radiation, in one embodiment, having a longer-wave wavelength range than the primary radiation. In particular, pure scatter or pure absorption of electromagnetic radiation is not what is meant by the term “wavelength conversion” in the present context.
A luminophore as described here—according to the application and type of radiation-emitting component—may preferably be used for generation of a low correlated color temperature (CCT), with a high color rendering index Ra (CRI), of cold white, warm white or red light, for example in display applications and general lighting. By comparison with conventionally used red-emitting luminophores, for example K2SiF6:Mn, SrLiAl3N4:Eu or (Sr,Ca)AlSiN3:Eu, which firstly have a very high spectral half-height width and/or secondly have emission bands in the long-wave red wavelength range, the light yield or luminous efficiency of the present luminophore is elevated on account of its narrowband emission, i.e. emission with a low spectral half-height width. Narrowband luminophores produce comparatively few photons in the deep red spectral region, which are perceived only very inefficiently by the human eye, while the red color impression of the light is simultaneously maintained.
The present luminophore also has an improved luminous efficacy of radiation. The quotient of luminous flux of the radiation and the radiant power thereof is referred to as luminous efficacy of radiation (LER). The greater the luminous efficacy of radiation, the greater the luminous flux utilizable by the eye at a given power. Thus, the spectral position of the emission of the luminophore described here has an extremely strong influence on the total luminous efficacy of radiation. Even small shifts in the emission maximum of otherwise identical emission bands lead to improvements in efficiency by up to 13%.
In the case of the luminophore described here, there is advantageously no use of hydrofluoric acid for production. By comparison, for example, K2SiF6:Mn is prepared industrially via a process in which large amounts of aqueous or concentrated hydrofluoric acid solutions are used. On account of the toxicity and difficulty of handling hydrofluoric acid, this entails very complex safety precautions. The luminophore described here is especially produced in a dry high-temperature process.
In one embodiment, the luminophore comprises a crystalline, for example ceramic, host lattice into which foreign elements are introduced as activator elements. The luminophore is, for example, a ceramic material.
The host lattice changes the electronic structure of the activator element in that primary radiation can be absorbed by the luminophore. The primary radiation can induce an electronic transition in the activator element, which can be converted back to the ground state with emission of secondary radiation. The activator element introduced into the host lattice is thus responsible for the wavelength-converting properties of the luminophore.
The crystalline host lattice is especially constructed from a generally three-dimensionally periodically repeating unit cell. In other words, the unit cell is the smallest repeating unit of the crystalline host lattice. The elements A, E and X each occupy positions therein, called point positions, within the unit cell of the host lattice. For example, the activator element RE and the tetravalent element E have equivalent point positions, or point positions in immediate proximity.
Description of the three-dimensional unit cell of the crystalline host lattice requires six lattice parameters: three lengths a, b and c, and three angles α, β and γ. The three lattice parameters a, b and c are the lengths of the lattice vectors that form the unit cell. The further three lattice parameters α, β and γ are the angles between these lattice vectors. α is the angle between b and c, β is the angle between a and c, and γ is the angle between a and b. V corresponds here to the volume of the unit cell.
In one embodiment, the luminophore has the general formula AzEeX6:RE where
In at least one embodiment, the luminophore has the general formula AzHfeX6:RE where
In at least one embodiment, the luminophore has the general formula AzHfeF6:RE where
In at least one embodiment, the luminophore has the general formula AzHfeF6:RE where
In at least one embodiment, the luminophore has the general formula AzGeeX6:RE where
In at least one embodiment, the luminophore has the general formula AzGeeF6:RE where
In at least one embodiment, the luminophore has the general formula AzGeeF6:RE where
The luminophore in this embodiment does not include any toxic heavy metals, for example cadmium or lead. The use of these heavy metals in electronic components is strictly limited by the legislator within the scope of RoHS guidelines.
In at least one embodiment, the luminophore has the general formula AzSneX6:RE where
In at least one embodiment, the luminophore has the general formula AzSneF6:RE where
Advantageously, the luminophore of the formula AzSneF6:RE may have a significantly higher luminous efficacy of radiation than the comparatively luminophore K2SiF6:Mn.
In at least one embodiment, the luminophore has the general formula AzSneF6:RE where
In at least one embodiment, the luminophore has the general formula AzPbeX6:RE where
In at least one embodiment, the luminophore has the general formula AzPbeF6:RE where
In at least one embodiment, the luminophore has the general formula AzPbeF6:RE where
In at least one embodiment, the luminophore has the general formula AzEeX6:RE where
In at least one embodiment, the luminophore has the general formula AzTieF6:RE where
In at least one embodiment, the luminophore has the general formula AzTieF6:RE where
In at least one embodiment, the luminophore has the general formula AzZreF6:RE where
In at least one embodiment, the luminophore has the general formula AzZreF6:RE where
In at least one embodiment, the luminophore has the general formula AzZreF6:RE where
The luminophore in this embodiment advantageously does not include any toxic heavy metals, for example cadmium or lead. The luminophore is suitable, for example, as an alternative to quantum dots, the use of which is subject to strict requirements as a result of the cadmium used within the scope of RoHS guidelines.
In at least one embodiment, X is selected from F, Cl, Br, I or combinations thereof. In at least one embodiment, X comprises or consists of F. These elements are readily available.
In at least one embodiment, RE is selected from Mn, Cr, Ni, Eu, Ce or combinations thereof. RE is preferably selected from Mn, Cr, Ni or combinations thereof. In at least one embodiment, RE consists of Mn, Cr or Ni.
In at least one embodiment, RE comprises manganese. In at least one embodiment, RE consists of manganese. This is especially in the Mn4+ form.
In at least one embodiment, the activator element RE has a molar proportion between 0.001 and 0.1 or 0.2 inclusive, based on E. In other words, between 0.1% and 10% or 20% inclusive of the point positions are substituted by RE. In particular, the molar proportion of RE based on E is between 0.005 and 0.5 inclusive, or between 0.01 and 0.10 inclusive.
In at least one embodiment, A is selected from Ca, Sr, Ba, Cd, Zn, Mg or combinations thereof. The luminophore preferably has a host lattice comprising AX6 octahedra and EX6 octahedra that are linked by a common X atoms.
The AX6 octahedra and EX6 octahedra are each formed by the X atoms. The AX6 octahedra and EX6 octahedra may have an octahedral vacancy. The octahedral vacancy is a region within the respective octahedron. For example, the term “octahedral vacancy” refers to the region within the octahedron which is unoccupied when touching spheres, i.e. X atoms, are placed at the vertices of the octahedron. The X atoms of the AX6 octahedra or of the EX6 octahedra form the octahedra, with the A or E atom present in the octahedral vacancy of the octahedron formed. More particularly, E is partly replaced by RE. In other words, the octahedron is centered around the E atom or the E atom. The A atom or the E atom are surrounded octahedrally by six X atoms. More particularly, all the atoms that form the octahedron have a similar distance from the A atom or E atom present in the octahedral vacancy. The X atom that joins the AX6 octahedron to the EX6 octahedron is a common X atom between the two octahedra. More particularly, every X atom of the octahedron is joined to a further octahedron. More particularly, the AX6 octahedra and EX6 octahedra are arranged alternately in particular spatial directions.
In at least one embodiment, the luminophore has the same crystal structure as CaZrF6, CaHfF6, ZnHfF6, CaPbF6, SrSnF6, CdHfF6, ZnZrF6, CaGeF6, ZnSnF6, MgGeF6, CdPbF6, ZnPbF6, MgPbF6, CaSnF6 or BaPbF6.
In at least one embodiment, the luminophore crystallizes in the cubic Fm
In at least one embodiment, the luminophore has the formula CaHfF6:RE. In one embodiment, RE here is Mn4+. Such a luminophore does not include any toxic heavy metals. In addition, the luminophore has a luminous efficacy of radiation up to 10% higher compared to comparative luminophores, for example K2SiF6:Mn4+.
In at least one embodiment, the luminophore has the formula CaZrF6:RE. In one embodiment, RE here is Mn4+. Such a luminophore does not include any toxic heavy metals. In addition, the luminophore has a luminous efficacy of radiation up to 10% higher compared to comparative luminophores, for example K2SiF6:Mn4+.
In at least one embodiment, the luminophore has the formula SrTiF6:RE. In one embodiment, RE here is Mn4+. Such a luminophore does not include any toxic heavy metals. In addition, the luminophore has an efficiency gain when used in a radiation-emitting component, and simultaneously improved color rendering.
In at least one embodiment, the luminophore has the formula ZnHfF6:RE. In one embodiment, RE here is Mn4+. Such a luminophore does not include any toxic heavy metals.
In at least one embodiment, the luminophore has the formula CaGeF6:RE. In one embodiment, RE here is Mn4+. Such a luminophore does not include any toxic heavy metals.
In at least one embodiment, the luminophore has the formula CaPbF6:RE. In one embodiment, RE here is Mn4+. Such a luminophore does not include any toxic heavy metals. In addition, the luminophore has a luminous efficacy of radiation up to 5% higher compared to comparative luminophores, for example K2SiF6:Mn4+.
In at least one embodiment, the luminophore has the formula BaPbF6:RE. In one embodiment, RE here is Mn4+.
In at least one embodiment, the luminophore has the formula ZnZrF6:RE. In one embodiment, RE here is Mn4+. Such a luminophore does not include any toxic heavy metals. In addition, the luminophore has a luminous efficacy of radiation comparable to the comparative luminophore K2SiF6:Mn4+.
In at least one embodiment, the luminophore has the formula MgGeF6:RE. In one embodiment, RE here is Mn4+. Such a luminophore does not include any toxic heavy metals.
In at least one embodiment, the luminophore has the formula CdPbF6:RE. In one embodiment, RE here is Mn4+. Such a luminophore does not include any toxic heavy metals. In addition, the luminophore has a luminous efficacy of radiation up to 5% higher compared to comparative luminophores, for example K2SiF6:Mn4+.
In at least one embodiment, the luminophore has the formula ZnPbF6:RE. In one embodiment, RE here is Mn4+.
In at least one embodiment, the luminophore has the formula MgPbF6:RE. In one embodiment, RE here is Mn4+. Such a luminophore has a slightly higher luminous efficacy of radiation compared to the comparative luminophore K2SiF6:Mn4+.
In at least one embodiment, the luminophore has the formula CdHfF6:RE. In one embodiment, RE here is Mn4+.
In at least one embodiment, the luminophore has the formula ZnZrF6:RE. In one embodiment, RE here is Mn4+. Such a luminophore does not include any toxic heavy metals.
In at least one embodiment, the luminophore has the formula CaSnF6:RE. In one embodiment, RE here is Mn4+. Such a luminophore does not include any toxic heavy metals. In addition, the luminophore has a luminous efficacy of radiation up to 15% higher compared to comparative luminophores, for example K2SiF6:Mn4+.
In at least one embodiment, the luminophore is in particle form, especially with grain sizes between 0.1 micrometer and 100 micrometers inclusive.
In at least one embodiment, local maxima in the excitation spectrum of the luminophore are between 320 nanometers and 420 nanometers inclusive, and between 430 nanometers and 550 nanometers inclusive. This means that the luminophore absorbs primary radiation in the near UV region and in the blue wavelength region. Thus, the luminophore is suitable for use in a radiation-emitting component with blue and/or near-UV primary radiation.
In at least one embodiment of the luminophore, an emission spectra measured between 600 nanometers and 700 nanometers has a multitude of emission peaks. The luminophore thus converts primary radiation, especially primary radiation in the blue wavelength region, to secondary radiation in the red wavelength region. The multitude of emission peaks are especially at least two emission peaks having different spectral intensity. The emission peaks are each shifted to shorter wavelengths compared to conventional red luminophores, such as SrLiAl3N4:Eu2+. The luminophore is suitable for use in combination with one or more further luminophores in a radiation-emitting component for generation of a white light with high color rendering. The further luminophores here are selected such that they emit green, yellow and/or orange light after excitation with primary radiation. Thus, a high color rendering index R9 is achieved. The color rendering index R9 is a specific color rendering index for saturated red light. Thus, the luminophore described here, when used in radiation-emitting components, compared to the comparative luminophore when used in radiation-emitting components at the same color locus, has an efficiency gain and simultaneously improved color rendering.
The emission spectrum is the distribution of the electromagnetic radiation emitted by the luminophore. Typically, the emission spectrum is represented in the form of a diagram in which a spectral intensity or a spectral radiant flux per wavelength interval (“spectral intensity/spectral radiant flux”) of the electromagnetic radiation emitted by the luminophore or another radiation-emitting element is represented as a function of wavelength λ. In other words, the emission spectrum is a curve in which wavelength is plotted on the x axis, and spectral intensity or spectral radiant flux on the y axis.
In at least one embodiment of the luminophore, a half-height width of an emission peak is between 2 nanometers and 20 nanometers inclusive. In particular, a half-height width of an emission peak is between 3 nanometers and 11 nanometers inclusive. The excitation spectrum here is in the near ultraviolet to blue spectral region, for example with an excitation maximum of about 490 nanometers. In particular, the half height width of each emission peak is between 3 nanometers and 11 nanometers inclusive. The narrowband-emitting luminophore produces comparatively few photons in the deep red spectral region that are perceived only inefficiently by the human eye, while the red color impression of the light and light yield are simultaneously increased.
In at least one embodiment, an emission maximum of an emission peak of the luminophore is between 624 nanometers and 635 nanometers inclusive. The emission maximum is the wavelength λmax at which the emission curve of the luminophore attains its maximum value. More particularly, the emission maximum of the luminophore, after excitation with primary radiation in the blue spectral region, is between 625 nm and 634 nm inclusive. Thus, the emission maximum of the luminophore after excitation with primary radiation in the blue spectral region is in the red spectral region. For example, the emission maximum of the luminophores CaZrF6:Mn and CaHfF6:Mn is at a wavelength at about 628.3 nm. For example, the emission maximum of the luminophore SrTiF6:Mn is at a wavelength at about 628.4 nm. For example, the emission maximum of the luminophore ZnHfF6:Mn is at a wavelength at about 632.7 nm. For example, the emission maximum of the luminophore CaGeF6:Mn is at a wavelength at about 628.6 nm. For example, the emission maximum of the luminophore CaPbF6:Mn is at a wavelength at about 629.1 nm. For example, the emission maximum of the luminophore SrSnF6:Mn is at a wavelength at about 626.6 nm. For example, the emission maximum of the luminophore BaPbF6:Mn is at a wavelength at about 632.5 nm. For example, the emission maximum of the luminophore ZnSnF6:Mn is at a wavelength at about 632.6 nm. For example, the emission maximum of the luminophore mgGeF6:Mn is at a wavelength at about 632.0 nm. For example, the emission maximum of the luminophore CdPbF6:Mn is at a wavelength at about 631.5 nm. For example, the emission maximum of the luminophore ZnPbF6:Mn is at a wavelength at about 632.8 nm. For example, the emission maximum of the luminophore mgPbF6:Mn is at a wavelength at about 633.0 nm. For example, the emission maximum of the luminophore CdHfF6:Mn in at a wavelength at about 627.3 nm. For example, the emission maximum of the luminophore ZnZrF6:Mn is at a wavelength at about 632.8 nm. For example, the emission maximum of the luminophore CaSnF6:Mn is at a wavelength at about 628.5 nm.
Advantageously, the emission maximum of CaZrF6:Mn, CaHfF6:Mn, SrTiF6:Mn, CaGeF6:Mn, CaPbF6:Mn, SrSnF6:Mn, CdHfF6:Mn and CaSnF6:Mn, by comparison with conventionally used red-emitting luminophores, especially K2SiF6:Mn, is shifted to shorter wavelengths. The sensitivity of the human eye to light is relatively low in the red spectral region, and rises nearly exponentially with decreasing wavelength. The effect of this is that the spectral position of the emission of the luminophore has an extremely strong influence on the overall spectral efficiency of a radiation-emitting component. Thus, in this spectral region, even small shifts of otherwise identical emission bands lead to changes in efficiency in the double-digit percent range of the luminophore.
In at least one embodiment of the luminophore, a luminous efficacy of radiation (LER) is greater than 180 lmW−1. For example, the luminous efficacy of radiation of the luminophore is greater than 202.7 lmW−1. The luminous efficacy of radiation is the quotient of the luminous flux of the radiation and its radiant power. The greater the luminous efficacy of radiation, the greater the luminous flux utilizable by the eye at a given power. Thus, the spectral position of emission of the luminophore described here has an extremely strong influence on the overall luminous efficacy of radiation. Even small shifts in the emission maximum of otherwise identical emission bands lead to improvements in efficiency by up to 15%. For example, the spectral efficiency of the luminophore CaZrF6:Mn is about 222.2 lmW−1. For example, the spectral efficiency of the luminophore CaHfF6:Mn is about 219.3 lmW−1. For example, the spectral efficiency of the luminophore SrTiF6:Mn is about 190.7 lmW−1. For example, the spectral efficiency of the luminophore ZnHfF6:Mn is about 194.9 lmW−1. For example, the spectral efficiency of the luminophore CaPbF6:Mn is about 213.4 lmW−1. For example, the spectral efficiency of the luminophore SrSnF6:Mn is about 228.6 lmW−1. For example, the spectral efficiency of the luminophore BaPbF6:Mn is about 191.4 lmW−1. For example, the spectral efficiency of the luminophore ZnSnF6:Mn is about 202.3 lmW−1. For example, the spectral efficiency of the luminophore mgGeF6:Mn is about 185.6 lmW−1. For example, the spectral efficiency of the luminophore CdPbF6:Mn is about 206.8 lmW−1. For example, the spectral efficiency of the luminophore ZnPbF6:Mn is about 181 lmW−1. For example, the spectral efficiency of the luminophore mgPbF6:Mn is about 205.2 lmW−1. For example, the spectral efficiency of the luminophore CdHfF6:Mn is about 256.8 lmW−1. For example, the spectral efficiency of the luminophore ZnZrF6:Mn is about 195.1 lmW−1. For example, the spectral efficiency of the luminophore CaSnF6:Mn is about 229.9 lmW−1.
In at least one embodiment of the luminophore, a dominant wavelength (λD) is between 597 nanometers and 621 nanometers inclusive. The dominant wavelength is the wavelength of monochromatic light that creates a similar perception of shade to the polychromatic light mixture to be described. In general, the dominant wavelength differs from the emission maximum. For example, the dominant wavelength of the luminophore CaZrF6:Mn is at a wavelength AD at about 615.4 nm. For example, the dominant wavelength of the luminophore CaHfF6:Mn is at a wavelength AD at about 617.2 nm. For example, the dominant wavelength of the luminophore SrTiF6:Mn is at a wavelength AD at about 612.7 nm. For example, the dominant wavelength of the luminophore ZnHfF6:Mn is at a wavelength λD at about 617.7 nm. The dominant wavelength of further working examples of the luminophore can be found in tables 2b, 2c and 2d.
The shape and position of the multitude of emission peaks have an influence on the luminous efficacy of radiation. It is advantageous here that the half height width of the emission peaks has a low width. Thus, comparatively few photons are emitted in the deep red spectral region, which are perceived only very inefficiently by the human eye, while the red color impression of the light is simultaneously retained.
In at least one embodiment, a color locus of the radiation emitted by the luminophore is at a CIE x value between 0.61 and 0.71 exclusive, and at a CIE y value between 0.29 and 0.39 inclusive, in the xy CIE standard color system at an excitation wavelength of 490 nm. The color locus of the luminophore CaZrF6:Mn is, for example, at CIE x 0.681 and CIE y 0.319. The color locus of the luminophore CaHfF6:Mn is, for example, at CIE x 0.685 and CIE y 0.315. The color locus of the luminophore SrTiF6:Mn is, for example, at CIE x 0.674 and CIE y 0.326. The color locus of the luminophore ZnHfF6:Mn is, for example, at CIE x 0.687 and CIE y 0.313. The color loci of further working examples of the luminophore can be found in tables 2b, 2c and 2d.
Also specified is a process for producing a luminophore. Preference is given to using the process described here to produce the luminophore according to the embodiment cited above. More particularly, all the remarks made in relation to the luminophore are also applicable to the process, and vice versa.
In one embodiment of the process for producing a luminophore having the general formula AzEeX6:RE,
In at least one embodiment, the reactants are selected from the group comprising halides, carbonates, sulfides, oxides, oxalates, imides, permanganates, nitrates, nitrites, sulfates, sulfites, hydrogensulfates, disulfates, thiosulfates, cyanides, cyanates, thiocyanates, acetates, carboxylic acid derivatives, ternary compounds, especially ammonium compounds, and amides, each of or with A, E, X and RE, and combinations thereof. Preferably, the reactants are selected from a group comprising halides, carbonates, sulfides, oxides, oxalates, imides and amides, each of or with A, E, X and RE, and combinations thereof.
In at least one embodiment, the reactants are selected from a group comprising AX2, EO2, ES2, EOX2, ACO3, A(MnO4)2 and REX2 and combinations thereof. Alternatively or additionally, it is possible to obtain the oxides, halides, sulfides and carbonates from organic precursor compounds that form the reactants in situ. For example, it is possible to obtain the oxides via the decarboxylation of oxalates or from carbonates.
In at least one embodiment, the reactants are selected from a group comprising calcium fluoride, hafnium(IV) oxide, manganese(II) chloride tetrahydrate, zinc chloride, strontium carbonate, titanium(IV) sulfide, zirconyl chloride octahydrate, germanium(IV) oxide, lead(II) chloride, tin(II) chloride dihydrate, barium fluoride, zinc carbonate, magnesium fluoride, cadmium chloride, cadmium fluoride, calcium permanganate tetrahydrate and combinations thereof.
In at least one embodiment, elemental X2 is used as reactant for component X.
In at least one embodiment, the reaction mixture is heated to a maximum temperature of not more than 1000° C. More particularly, the reaction mixture is heated to a maximum temperature of not more than 650° C. Preference is given to heating the reaction mixture to a maximum temperature of not more than 450° C.
In at least one embodiment, the heating takes place in an F2 stream. More particularly, in the course of heating, up to 100% by volume of F2 is passed through the reaction mixture. Alternatively, the stream includes F2 and an inert gas. Preferably, in the course of heating, up to 10% by volume of F2 in an inert gas is passed through the reaction mixture. For example, the inert gas is He, Ne, Kr, Ar, Xe, N2 or SF6. It is thus possible to ensure oxidizing conditions.
In at least one embodiment of the process, no hydrofluoric acid solution is used. The hazard potential resulting from addition of a hydrofluoric acid solution is accordingly avoided.
In at least one embodiment, the heating is a dry high-temperature method. This means that no additional solvents or acids are added in the course of heating. The hazard potential resulting from addition of an acid, especially a hydrofluoric acid solution, is accordingly avoided.
The conventionally used red-emitting luminophore K2SiF6:Mn, by contrast, is synthesized industrially with the aid of an aqueous hydrofluoric acid solution. On account of the toxicity and difficulty of handling hydrofluoric acid, this entails very complex safety precautions. In the case of the luminophore described here, however, synthesis is not possible with the aid of an aqueous solution, especially a hydrofluoric acid solution, since the reactants, for example CaF2 with a solubility of only 0.015 g/L (at 18° C.), SrF2 with a solubility of only 0.12 g/L (at 27° C.), MgF2 with a solubility of only 0.087 g/L (at 18° C.) and BaF2 with a solubility of only 0.16 g/L (at 18° C.), can barely be dissolved in water, and hence synthesis with an aqueous hydrofluoric acid solution is impossible. In addition, the dry high-temperature process is a simplified synthesis route compared to the processes with hydrofluoric acid.
In at least one embodiment of the process, the reactants are homogenized. The resultant reaction mixture of the reactants can then be introduced into the crucible, for example into a corundum boat, and placed in a furnace, especially a tubular furnace, through which up to 100% by volume of F2 is being passed.
In at least one embodiment, the process comprises stepwise heating of the reaction mixture. What is meant by stepwise heating is that the reaction mixture is heated to at least one intermediate temperature at least one heating rate, and the reaction mixture is kept at an intermediate temperature with a hold time before the maximum temperature is attained. The intermediate temperature is especially lower than the maximum temperature. More particularly, the stepwise heating has two heating rates that may be the same or different.
The intermediate temperature is, for example, between 50° C. and 400° C. inclusive. The hold time is, for example, between one hour and 30 days inclusive. The heating rate is, for example, between 0.05° C. per minute and 5° C. per minute inclusive.
In at least one embodiment, the heating comprises at least one cooling step. The cooling step is especially effected after a heating rate. In the cooling step, the reaction mixture in the furnace is cooled down to a minimum temperature. The minimum temperature is especially between 20° C. and 50° C. inclusive. After the cooling step, the reaction mixture is preferably blended and then heated again.
For example, in a first process step, the reaction mixture is heated to at least two intermediate temperatures at at least two heating rates and kept at an intermediate temperature in each case for at least two hold times. Subsequently, the reaction mixture is cooled down to a minimum temperature in the furnace. In a mixed process step, the reaction mixture is placed in the furnace again and heated at at least one heating rate to an intermediate temperature or maximum temperature and kept at the intermediate temperature or maximum temperature for at least one hold time. Optionally, the reaction mixture, after being heated to a minimum temperature, may be cooled and mixed and heated again at a heating rate in the furnace. After the last hold time at the maximum temperature, the reaction mixture is cooled down to a minimum temperature in the furnace, and a luminophore is obtained.
For example, the reaction mixture is heated at a first heating rate to a first intermediate temperature between 50° C. and 100° C. inclusive. Subsequently, the reaction mixture is kept constant at this intermediate temperature for a first hold time between one hour and 20 hours inclusive. The heating rate and hold time are repeated until a second heating temperature between 300° C. and 370° C. inclusive is attained. The second intermediate temperature is maintained for a second hold time for between two days and 20 days inclusive. Optionally, the reaction mixture may be heated at a heating rate to a third intermediate temperature of about 400° C. and kept constant for a third hold time for five days to 30 days inclusive. Subsequently, the reaction mixture is cooled down to a minimum temperature of about 30° C. in the furnace, removed from the furnace, mixed and placed back into the furnace. The reaction mixture is heated at a heating rate to a fourth intermediate temperature or to a maximum temperature between 300° C. and 450° C. inclusive and kept at this intermediate temperature or maximum temperature for a fourth hold time of two days to 14 days inclusive. Optionally, the reaction mixture can be heated to a maximum temperature of 450° C. at a fifth heating rate and kept at this maximum temperature for a fifth hold time for one day. It is also possible, after a fourth intermediate temperature, to cool the reaction mixture back down to a minimum temperature and heat it again in the furnace at a heating rate to a maximum temperature of 450° C. This maximum temperature is kept constant for four to 14 days. Subsequently, the reaction mixture is cooled down to a minimum temperature.
In at least one embodiment of the process, a stoichiometric composition of the reactants calcium fluoride, zirconyl chloride octahydrate and manganese(II) chloride tetrahydrate is provided. More particularly, a stoichiometric composition of these reactants is suitable for preparation of a luminophore of the formula CaZrF6:Mn.
In at least one embodiment of the process, a stoichiometric composition of the reactants calcium fluoride, hafnium(IV) oxide and manganese(II) chloride tetrahydrate is provided. More particularly, a stoichiometric composition of these reactants is suitable for preparation of a luminophore of the formula CaHfF6:Mn.
In at least one embodiment of the process, a stoichiometric composition of the reactants strontium carbonate, titanium(IV) sulfide and manganese(II) chloride tetrahydrate is provided.
More particularly, a stoichiometric composition of these reactants is suitable for preparation of a luminophore of the formula SrTiF6:Mn.
In at least one embodiment of the process, a stoichiometric composition of the reactants zinc chloride, hafnium(IV) oxide and manganese(II) chloride tetrahydrate is provided. More particularly, a stoichiometric composition of these reactants is suitable for preparation of a luminophore of the formula ZnHfF6:Mn.
In at least one embodiment of the process, a stoichiometric composition of the reactants calcium fluoride, germanium(IV) oxide and manganese(II) chloride tetrahydrate is provided. More particularly, a stoichiometric composition of these reactants is suitable for preparation of a luminophore of the formula CaGeF6:Mn.
In at least one embodiment of the process, a stoichiometric composition of the reactants calcium fluoride, lead(II) chloride and manganese(II) chloride tetrahydrate is provided. More particularly, a stoichiometric composition of these reactants is suitable for preparation of a luminophore of the formula CaPbF6:Mn.
In at least one embodiment of the process, a stoichiometric composition of the reactants strontium carbonate, tin(II) chloride dihydrate and manganese(II) chloride tetrahydrate is provided. More particularly, a stoichiometric composition of these reactants is suitable for preparation of a luminophore of the formula SrSnF6:Mn.
In at least one embodiment of the process, a stoichiometric composition of the reactants barium fluoride, lead(II) chloride and manganese(II) chloride tetrahydrate is provided. More particularly, a stoichiometric composition of these reactants is suitable for preparation of a luminophore of the formula BaPbF6:Mn.
In at least one embodiment of the process, a stoichiometric composition of the reactants zinc carbonate, tin(II) chloride dihydrate and manganese(II) chloride tetrahydrate is provided. More particularly, a stoichiometric composition of these reactants is suitable for preparation of a luminophore of the formula ZnSnF6:Mn.
In at least one embodiment of the process, a stoichiometric composition of the reactants magnesium fluoride, germanium(IV) oxide and manganese(II) chloride tetrahydrate is provided. More particularly, a stoichiometric composition of these reactants is suitable for preparation of a luminophore of the formula MgGeF6:Mn.
In at least one embodiment of the process, a stoichiometric composition of the reactants cadmium chloride, lead(II) chloride and manganese(II) chloride tetrahydrate is provided. More particularly, a stoichiometric composition of these reactants is suitable for preparation of a luminophore of the formula CdPbF6:Mn.
In at least one embodiment of the process, a stoichiometric composition of the reactants zinc carbonate, lead(II) chloride and manganese(II) chloride tetrahydrate is provided. More particularly, a stoichiometric composition of these reactants is suitable for preparation of a luminophore of the formula ZnPbF6:Mn.
In at least one embodiment of the process, a stoichiometric composition of the reactants magnesium fluoride, lead(II) chloride and manganese(II) chloride tetrahydrate is provided. More particularly, a stoichiometric composition of these reactants is suitable for preparation of a luminophore of the formula MgPbF6:Mn.
In at least one embodiment of the process, a stoichiometric composition of the reactants cadmium fluoride, manganese fluoride and hafnium(IV) chloride tetrahydrate is provided. More particularly, a stoichiometric composition of these reactants is suitable for preparation of a luminophore of the formula CdHfF6:Mn.
In at least one embodiment of the process, a stoichiometric composition of the reactants zinc carbonate, zirconyl chloride octahydrate and manganese(II) chloride tetrahydrate is provided. More particularly, a stoichiometric composition of these reactants is suitable for preparation of a luminophore of the formula ZnZrF6:Mn.
In at least one embodiment of the process, a stoichiometric composition of the reactants calcium fluoride, tin(II) chloride dihydrate and calcium permanganate tetrahydrate is provided. More particularly, a stoichiometric composition of these reactants is suitable for preparation of a luminophore of the formula CaSnF6:Mn.
Also specified is a radiation-emitting component comprising at least one luminophore. The luminophore according to the abovementioned embodiments is preferably suitable and intended for use in a radiation-emitting component as described here. Features and embodiments that are mentioned solely in connection with the luminophore and/or process are also applicable to the radiation-emitting component, and vice versa.
The radiation-emitting component is a component that emits electromagnetic radiation in operation. For example, the radiation-emitting component is a light-emitting diode (LED).
In at least one embodiment, the radiation-emitting component comprises a semiconductor chip which, in operation, emits electromagnetic radiation in a first wavelength range. The semiconductor chip may comprise an active layer sequence containing an active region which, in operation of the component, can generate the electromagnetic radiation of the first wavelength range, the primary radiation. The semiconductor chip is, for example, a light-emitting diode chip or a laser diode chip. The primary radiation which is generated in the semiconductor chip may be emitted through a radiation exit face of the semiconductor chip. The primary radiation may form a beam path or follow a beam path.
The primary radiation may especially comprise wavelengths in the visible region. For example, the semiconductor chip emits primary radiation in the blue spectral region, especially in the wavelength range from 400 nm or 430 nm to 550 nm inclusive, preferably from 450 nm to 520 nm inclusive, more preferably from 470 nm to 510 nm inclusive.
In at least one embodiment, the radiation-emitting component comprises a conversion element including a luminophore having the general formula AzEeX6:RE that converts electromagnetic radiation in the first wavelength range to electromagnetic radiation in a second wavelength range, where
The properties of the luminophore are already disclosed in relation to the luminophore and are likewise applicable to the luminophore in the radiation-emitting component. The luminophore converts the primary radiation completely or at least partly to electromagnetic radiation in a second wavelength range, called the secondary radiation. In particular, the secondary radiation has at least partly different wavelength ranges than the primary radiation.
The conversion element is especially disposed in the beam path of the primary radiation in such a way that at least a portion of the primary radiation hits the conversion element.
In at least one embodiment, the conversion element is applied in direct contact on the radiation exit face of the semiconductor chip.
In at least one embodiment, the conversion element is applied with the aid of an adhesive layer on the radiation exit face.
In at least one embodiment, the semiconductor chip and the conversion element are disposed in the recess of a housing. In a further embodiment, the semiconductor chip and/or the conversion element or at least partly surrounded by an encapsulant.
In at least one embodiment, the semiconductor chip and the conversion element are disposed in the recess of a housing, with the recess of the housing filled with an encapsulant that at least partly surrounds the semiconductor chip, and the conversion element being disposed on the side of the encapsulant remote from the semiconductor chip.
In at least one embodiment, the semiconductor chip is disposed in the recess of a housing, with the recess of the housing filled with an encapsulant that at least partly surrounds the semiconductor chip, and the conversion element disposed on the side of the encapsulant remote from the semiconductor chip outside the recess of the housing. It is optionally possible for particles, for example luminophores for scattering particles, to be embedded within the encapsulant.
In at least one embodiment, the conversion element is part of an encapsulant of the radiation-emitting component, for the conversion element forms the encapsulant. The semiconductor chip is especially embedded into the conversion element and at least partly surrounded by the conversion element. In at least one embodiment, the encapsulant is disposed in the recess of the housing.
In at least one embodiment, the recess of the housing between the semiconductor chip and the conversion element is free of any encapsulant and/or further layers or components.
In at least one embodiment, the encapsulant has a transparency to electromagnetic radiation, especially the primary radiation, of at least 85%, especially of at least 95%.
In at least one embodiment, the encapsulant comprises glass such as silicate, waterglass or quartz glass, or polymers such as polystyrene, polysiloxane, polysilazane, PMMA, polycarbonate, polyacrylate, polytetrafluoroethylene, polyvinyl, silicone resin, silicone or epoxy resin or combinations thereof.
Such a radiation-emitting component can especially generate narrowband radiation in the red wavelength range after excitation with primary radiation. In combination with one or more further luminophores, the radiation-emitting component may thus preferably be used for generation of cold white, warm white or—in the case of full conversion—red light, for example in display applications.
In at least one embodiment, the conversion element converts the primary radiation partly to secondary radiation, with the unconverted portion of the primary radiation being transmitted by the conversion element. In other words, partial conversion of the primary radiation to secondary radiation takes place. The radiation-emitting component in this case emits mixed light composed of the primary radiation and secondary radiation. For example, the radiation-emitting component emits light composed of primary radiation in the blue spectral region and secondary radiation in the red spectral region. More particularly, combination with one or more further luminophores can generate white light with a high color rendering index Ra and a low color temperature.
In at least one embodiment, no primary radiation is transmitted by the conversion element. What is meant by “no” in this context is that so little primary radiation is transmitted that it no longer perceptibly affects the light emitted by the component. For example, not more than 10%, especially not more than 5% and preferably not more than 1% of the primary radiation is transmitted by the conversion element. In that case, the radiation-emitting component emits merely the secondary radiation. In other words, for conversion of the primary radiation to secondary radiation takes place. Thus, the conversion element converts the primary radiation outwardly virtually completely to secondary radiation. For example, the radiation-emitting component emits red light without a blue component. By comparison with commercial red luminophores having a similar dominant wavelength, especially K2SiF6:Mn4+, working examples of the present luminophore, on account of its narrowband emission at shorter wavelengths in the red region, have a distinctly superior luminous efficiency in the red region.
In at least one embodiment, the conversion element is free of a further luminophore. What is meant by “free of a further luminophore” is that only one luminophore covered by the formula of the luminophore AzEeX6:RE or a mixture of different luminophores covered by the formula of the luminophore AzEeX6:RE are present in the conversion element of the radiation-emitting component for wavelength conversion and lead to a wavelength conversion within the radiation-emitting component.
In at least one embodiment, the conversion element comprises a second luminophore that converts electromagnetic radiation in a first wavelength range to electromagnetic radiation in a third wavelength range. The third wavelength range is different than the first and the second wavelength range.
In at least one embodiment, the second luminophore is a yellow-emitting luminophore that converts the primary radiation to a yellow secondary radiation. In particular, the second luminophore absorb some converts blue primary radiation, especially having a wavelength range from 430 nm to 550 nm inclusive, preferably from 450 nm to 520 nm inclusive.
Yellow-emitting luminophores used may especially be garnet luminophores, for example (Lu,Y,Gd,Tb)3(Al,Ga)5O12:Ce, orthosilicates, for example (Ca,Ba,Sr)2SiO4:Eu2+, or nitrides such as La3Si6N11:Ce3+. The luminophore (Lu,Y,Gd,Tb)3(Al,Ga)5O12:Ce has at least one of the elements Lu, Y, Gd and Tb and at least one of the elements Al and Ga. The luminophore (Ca,Ba,Sr)2SiO4:Eu2+ has at least one of the elements Ca, Ba and Sr.
In at least one embodiment, the second luminophore is a green-emitting luminophore that converts the primary radiation to a green secondary radiation. More particularly, the second luminophore absorbs and converts blue primary radiation, especially having a wavelength range from 530 nm to 590 nm inclusive, preferably from 550 nm to 590 nm inclusive.
The green-emitting luminophore used may especially be the garnet luminophore (Lu,Y,Gd,Tb)3(Al,Ga)5O12:Ce.
Use of a second luminophore in combination with a luminophore of the general formula AzEeX6:RE allows the color locus of the radiation-emitting component to be adjusted.
When a second luminophore is used in combination with a luminophore of the general formula AaEeX6:RE in the radiation-emitting component, it is possible to generate a mixed light having a color locus in the warm white region. More particularly, the mixed light with a color locus in the warm white region is generated by a combination of the blue primary radiation from the semiconductor chip, the red secondary radiation from the luminophore described here, and the yellow or green secondary radiation from the yellow- or green-emitting second luminophore. It is thus possible to generate warm white mixed light having a high color rendering index Ra, for example about 92, and a color temperature between 2600 K and 3200 K inclusive, especially 2993 K and 3008 K inclusive.
In at least one embodiment, the conversion element comprises at least two differently emitting luminophores. The conversion element includes, for example, the present luminophore, a green-emitting luminophore and a yellow-emitting luminophore.
By comparison with a radiation-emitting component with the conventionally used red-emitting luminophore K2SiF6:Mn in combination with the same blue-emitting semiconductor chip and the same second luminophore, the radiation-emitting component described here can lead to a higher luminous efficacy of radiation LER by at least 2%.
In addition, a high red color rendering index R9 is achieved. The red color rendering index R9 is a specific color rendering index for saturated red colors.
Thus, the radiation-emitting component described here, by comparison with the conventional radiation-emitting component, with the same color locus, has an efficiency gain and simultaneously improved color rendering.
In at least one embodiment, the luminophore in the conversion element is in the form of a ceramic or in a matrix material. A luminophore in the form of a ceramic is especially very substantially free of any matrix material and/or any further luminophore. The ceramic formed from the luminophore preferably has a low porosity. It is thus possible to prevent or virtually prevent unwanted light scatter, and there is good removal of heat.
Alternatively, the luminophore, especially in particle form, is embedded in a matrix material. The matrix material comprises, for example, the abovementioned materials for encapsulation. More particularly, the surface of the luminophore may be passivated for embedding into a matrix material. It is possible for more than one luminophore to be embedded in a matrix material. For example, particles of two luminophores are embedded in the matrix material.
Further advantageous embodiments, configurations and developments of the luminophore, of the process for producing a luminophore and of the radiation-emitting component will be apparent from the working examples that follow, which are described in conjunction with the figures.
Elements that are the same, of the same type will have the same effect are given the same reference numerals in the figures. The figures and size ratios of the elements shown in the figures with respect to one another should not be considered to be true to scale. Instead, individual elements, especially layer thicknesses, may be shown in excessively large size for better illustratability and/or the better understanding.
What is meant here and hereinafter by “vertex-linked” is that two octahedra are joined to one another via a common vertex 4. The vertex 4 in the present case is a common F atom.
The AF6 octahedron and the EF6 octahedron each have an octahedral vacancy. The octahedral vacancy is a region within the respective octahedron. The fluorine atoms form the octahedron, with the A atom and E atom present in the octahedral vacancy of the octahedron formed by the fluorine atoms. In this case, preferably all atoms that form the octahedron at a similar distance from the A atom and the E atom present in the octahedral gap.
At least one AF6 octahedron and one EF6 octahedron are links to one another via a fluorine atom. The fluorine atom that links the AF6 octahedron and the EF6 octahedron is a common fluorine atom.
In
Table 1 below shows the crystallographic data of the working examples CaZrF6:Mn, CaHfF6:Mn and ZnHfF6:Mn, CaGeF6:Mn, CaPbF6:Mn, SrSnF6:Mn, BaPbF6:Mn, ZnSnF6:Mn, MgGeF6:Mn, CdPbF6:Mn, ZnPbF6:Mn, MgPbF6:Mn, CdHfF6:Mn, CaSnF6:Mn, ZnZrF6:Mn of the luminophores 1. The crystallographic data were obtained from a Rietveld refinement or Le Bail refinement, as described in detail in relation to
The composition of the luminophore 1 according to the working example SrTiF6:Mn was confirmed by means of elemental analysis (MP-AES, microwave plasma atomic emission spectroscopy). The actual value for Sr is 37.0% by mass and the actual value for Ti in the luminophore SrTiF6:Mn is 17.8% by mass. The theoretical value for Sr is 35.0% by mass and the theoretical value for Ti is 18.2% by mass. The variances between measured actual values and calculated theoretical values are within the standard experimental error limits for the analysis method used.
Aside from the luminophore 1 having the formula CaHfF6:Mn, no secondary crystalline phases are present. Here too, good agreement of the calculated powder diffractogram G2 with the measure diffractogram G1 is apparent. It was thus confirmed that CaZrF6:Mn and CaHfF6:Mn are isotypic with one another. What is meant by the term “isotypic” is that the compounds have the same crystal structure. Thus, the working examples CaZrF6:Mn and CaHfF6:Mn of the luminophore 1 have the same crystal structure.
By subsequent Rietveld refinement, shown in
Tables 2a-2d list of the luminous efficacies of radiation LER, the relative luminous efficacies of radiation LER, the emission maxima λmax, the dominant wavelengths λD and the color loci CIE x and CIE y for the luminophores 1 according to the working examples CaZrF6:Mn, CaHfF6:Mn, SrTiF6:Mn, ZnHfF6:Mn, CaGeF6:Mn, CaPbF6:Mn, SrSnF6:Mn, BaPbF6:Mn, ZnSnF6:Mn, MgGeF6:Mn, CdPbF6:Mn, ZnPbF6:Mn, MgPbF6:Mn, CdHfF6:Mn, CaSnF6:Mn, ZnZrF6:Mn and the comparative example K2SiF6:Mn. The results from tables 2a-2d show that the inventive luminophores 1 having the formula CaZrF6:Mn, CaHfF6:Mn, SrTiF6:Mn, ZnHfF6:Mn, CaGeF6:Mn, CaPbF6:Mn, SrSnF6:Mn, ZnSnF6:Mn, MgGeF6:Mn, CdPbF6:Mn, ZnPbF6:Mn, MgPbF6:Mn, CdHfF6:Mn, CaSnF6:Mn and ZnZrF6:Mn have a lower dominant wavelength compared to the comparative example K2SiF6:Mn. BaPbF6:Mn, by contrast, has a greater dominant wavelength K2SiF6:Mn. In addition, the luminophores 1 having the formula CaZrF6:Mn, CaHfF6:Mn, CaPbF6:Mn, SrSnF6:Mn, CdPbF6:Mn and mgPbF6:Mn have a higher luminous efficacy of radiation than K2SiF6:Mn.
In the process according to the working example of
In a next process step S2, the reaction mixture is heated stepwise in the furnace. This means that the reaction mixture is heated at at least one heating rate to at least one intermediate temperature and kept at an intermediate temperature for at least one hold time. Subsequently, the reaction mixture is cooled to room temperature by a cooling step and mixed.
In a further process step S3, the reaction mixture is again inserted into the tubular furnace and heated stepwise. The reaction mixture is heated at at least one heating rate to at least one intermediate temperature or a maximum temperature and kept at an intermediate temperature for maximum temperature for at least one hold time.
The heating here is a dry high-temperature method. This means that no additional solvents or acids are added in the course of heating. The hazard potential resulting from the addition of an acid, especially a hydrofluoric acid solution, is accordingly avoided.
Preparation of the Luminophore 1 According to the Working Example CaZrF6:Mn
A stoichiometric composition of the reactants calcium fluoride (780.8 mg, 10 mmol), zirconyl chloride octahydrate (3.144 g, 9.8 mmol) and manganese(II) chloride tetrahydrate (39.5 mg, 0.2 mmol) is mixed intimately in an agate mortar and introduced into a corundum boat. This corundum boat is placed in a corundum tube heatable by a tubular furnace, through which 10% by volume of F2 in argon is passed. The intermediate temperature is increased from 30° C. by 20° C. (0.33° C./min), and this intermediate temperature is kept constant for one hour. The stepwise increase in the intermediate temperature and the hold times are repeated until the temperature reaches 370° C. The intermediate temperature is increased at 4° C./min to 400° C. within three days. After a hold time of five further days, the reaction mixture is cooled down to a minimum temperature of 30° C., crushed using a glassy carbon mortar and pestle, and put back in the furnace. The furnace is heated up again to 400° C. at a heating rate of 4° C./min and, after two further days, the intermediate temperature is increased at 4° C./min to a maximum temperature of 450° C. and kept at that maximum temperature for a further day. Subsequently, the reaction mixture is removed from the oven and cooled down, and the luminophore 1 having the formula CaZrF6:Mn is obtained.
The synthesis is thus a dry high-temperature process, in which it is possible to dispense with the use of hydrofluoric acid solutions. Owing to the sparing solubility of CaF2 in water, it is not possible to prepare CaZrF6:Mn by the process in aqueous HF which is otherwise customary in industry for complex fluoride luminophores.
Preparation of the Luminophore 1 According to the Working Example CaHfF6:Mn
A stoichiometric composition of the reactants calcium fluoride (78.3 mg, 1 mmol), hafnium(IV) oxide (199.9 mg, 0.95 mmol) and manganese(II) chloride tetrahydrate (9.6 mg, 0.05 mmol) is mixed intimately in an agate mortar and introduced into a corundum boat. This corundum boat is placed in a corundum tube heatable by a tubular furnace, through which 10% by volume of F2 in argon is passed. The intermediate temperature is increased from 30° C. by 20° C. (0.33° C./min), and this intermediate temperature is kept constant for one hour. The stepwise increase in the intermediate temperature and the hold times are repeated until the temperature reaches 370° C. After six days, the reaction mixture is cooled down to a minimum temperature of 30° C. Subsequently, the reaction mixture is removed from the furnace, crushed using a glassy carbon mortar and pestle, and put back in the furnace. The furnace is heated up again to 400° C. at a heating rate of 4° C./min and, after five further days, the reaction mixture is cooled down to a minimum temperature of 30° C., crushed with a mortar and pestle and subjected to heat treatment at 450° C. for a further 14 days at 450° C. in a fluorine stream. The luminophore 1 having the formula CaHfF6:Mn is obtained.
The synthesis is thus a dry high-temperature process, in which it is possible to dispense with the use of hydrofluoric acid solutions. Owing to the sparing solubility of CaF2 in water, it is not possible to prepare CaHfF6:Mn by the process in aqueous HF which is otherwise customary in industry for complex fluoride luminophores.
Preparation of Luminophore 1 According to the Working Example SrTiF6:Mn
A stoichiometric composition of the reactants strontium carbonate (590.3 mg, 4 mmol), titanium(IV) sulfide (443.0 mg, 3.96 mmol) and manganese(II) chloride tetrahydrate (10.3 mg, 0.04 mmol) is mixed intimately in an agate mortar and introduced into a corundum boat. This corundum boat is placed in a corundum tube heatable by a tubular furnace, through which 10 ml/min of 10% by volume of F2 in argon is passed. The intermediate temperature is increased to 100° C. (5° C./h), and this intermediate temperature is maintained for 20 hours. The stepwise increase in the intermediate temperature by 100° C. each time (10° C./h) and the hold times (10 hours) are repeated until the temperature reaches 300° C. After four days, the reaction mixture is cooled down to a minimum temperature of 30° C., and the reaction mixture is removed from the furnace, crushed using a glassy carbon mortar and pestle and put back in the furnace. The furnace is heated again to 300° C. at a heating rate of 4° C./min and the reaction mixture is reacted again with a gas stream of 10 ml/min of 5% by volume of F2 in argon for a further 10 days. The luminophore 1 having the formula SrTiF6:Mn is obtained.
The synthesis is thus a dry high-temperature process, in which it is possible to dispense with the use of hydrofluoric acid solutions. Owing to the sparing solubility of CaF2 in water, it is not possible to prepare CaZrF6:Mn by the process in aqueous HF which is otherwise customary in industry for complex fluoride luminophores.
Preparation of the Luminophore 1 According to the Working Example ZnHfF6:Mn
A stoichiometric composition of the reactants zinc chloride (135.1 mg, 1 mmol), hafnium(IV) oxide (200.5 mg, 0.95 mmol) and manganese(II) chloride tetrahydrate (11.8 mg, 0.05 mmol) is mixed intimately in an agate mortar and introduced into a corundum boat. This corundum boat is placed in a corundum tube heatable by a tubular furnace, through which 10% by volume of F2 in argon is passed. The intermediate temperature is increased from 30° C. by 20° C. (0.33° C./min), and this intermediate temperature is kept constant for one hour. The stepwise increase in the intermediate temperature and the hold times are repeated until the temperature reaches 370° C. After a hold time of two days, the furnace is cooled down to a minimum temperature of 30° C., the reaction mixture is removed, crushed using a glassy carbon mortar and pestle, and put back in the furnace. The furnace is heated up again to 400° C. at a heating rate of 4° C./min and the reaction mixture is fluorinated for a further four days, before being cooled down again to 30° C. and crushed with a mortar and pestle. The reaction mixture is put back in the furnace and heated at 4° C./min to a maximum temperature of 450° C., and the reaction mixture is subjected to heat treatment in a fluorine stream for a further four days. The luminophore 1 having the formula ZnHfF6:Mn is obtained.
The synthesis is thus a dry high-temperature process, in which it is possible to dispense with the use of hydrofluoric acid solutions.
Preparation of the Luminophore 1 According to the Working Example CaGeF6:Mn
For the synthesis of CaGeF6:Mn, calcium fluoride (236.5 mg, 3.03 mmol), germanium(IV) oxide (GeO2, 310.6 mg, 2.97 mmol) and manganese(II) chloride tetrahydrate (MnCl2.4H2O, 8.0 mg, 0.04 mmol) are mixed intimately in an agate mortar and introduced into a corundum boat. This corundum boat is placed in a corundum tube heatable by a tubular furnace, through which 10% by volume of F2 in argon is passed at 5 ml/min. The temperature is increased from 30° C. to 100° C. within 5 h, which is maintained for 20 h, before the temperature is increased stepwise by 100° C. (10° C./h, hold time 10 h) up to 400° C. After a hold time of 13 days, the furnace is cooled down to a temperature of 30° C., and the reaction mixture is removed, crushed using a glassy carbon mortar and pestle, and put back in the furnace. The reaction mixture is heated in the furnace at 4° C./min to a temperature of 400° C. and subjected to heat treatment in a fluorine stream for a further 15 days. The luminophore 1 having the formula CaGeF6:Mn is obtained.
The synthesis is thus a dry high-temperature process, in which it is possible to dispense with the use of hydrofluoric acid solutions. Owing to the sparing solubility of CaF2 in water, it is not possible to prepare CaGeF6:Mn by the process in aqueous HF which is otherwise customary in industry for complex fluoride luminophores.
Preparation of the Luminophore 1 According to the Working Example CaPbF6:Mn
Calcium fluoride (CaF2, 78.7 mg, 1.00 mmol), lead(II) chloride (PbCl2, 278.7 mg, 1.00 mmol) and manganese(II) chloride tetrahydrate (MnCl2.4H2O, 2.2 mg, 0.01 mmol) are mixed intimately in an agate mortar and introduced into a corundum boat. This corundum boat is placed in a corundum tube heatable by a tubular furnace, through which 10% by volume of F2 in argon is passed at 5 ml/min. The temperature is increased from 30° C. to 100° C. within 5 h, which is maintained for 20 h, before the temperature is increased stepwise by 100° C. (10° C./h, hold time 10 h) up to 400° C. After a hold time of 6 days, the furnace is cooled down to a temperature of 30° C., and the reaction mixture is removed, crushed using a glassy carbon mortar and pestle, and put back in the furnace. The reaction mixture is heated in the furnace at 4° C./min to a temperature of 400° C. and subjected to heat treatment in a fluorine stream for a further 8 days. The luminophore 1 having the formula CaPbF6:Mn is obtained.
The synthesis is thus a dry high-temperature process, in which it is possible to dispense with the use of hydrofluoric acid solutions. Owing to the sparing solubility of CaF2 in water, it is not possible to prepare CaPbF6:Mn by the process in aqueous HF which is otherwise customary in industry for complex fluoride luminophores. Furthermore, lead(IV) in quantitative analysis serves as a detection reagent for manganese ions, which are oxidized under acidic conditions to give the pink permanganate ion. Therefore, the presence of Mn(IV) under acidic conditions alongside Pb(IV) is not possible. Accordingly, it is not possible to prepare CaPbF6:Mn by the process in aqueous HF which is otherwise customary in industry for complex fluoride luminophores.
Preparation of the Luminophore 1 According to the Working Example SrSnF6:Mn
For the synthesis of SrSnF6:Mn, strontium carbonate (SrCO3, 297.6 mg, 2.02 mmol), tin(II) chloride dihydrate (SnCl2.2H2O, 441.4 mg, 1.96 mmol) and manganese(II) chloride tetrahydrate (MnCl2.4H2O, 9.5 mg, 0.05 mmol) are mixed intimately in an agate mortar and introduced into a corundum boat. This corundum boat is placed in a corundum tube heatable by a tubular furnace, through which 10% by volume of F2 in argon is passed at 5 ml/min. The temperature is increased from 30° C. to 100° C. within 5 h, which is maintained for 20 h, before the temperature is increased stepwise by 100° C. (10° C./h, hold time 10 h) up to 400° C. After a hold time of 7 days, the furnace is cooled down to a minimum temperature of 30° C., and the reaction mixture is removed, crushed using a glassy carbon mortar and pestle, and put back in the furnace. The reaction mixture is heated in the furnace at 4° C./min up to 400° C., and the reaction mixture is subjected to heat treatment in a fluorine stream for a further 16 days. The luminophore 1 having the formula SrSnF6:Mn is obtained.
The synthesis is thus a dry high-temperature process, in which it is possible to dispense with the use of hydrofluoric acid solutions. Owing to the sparing solubility of CaF2 in water, it is not possible to prepare SrSnF6:Mn by the process in aqueous HF which is otherwise customary in industry for complex fluoride luminophores.
Preparation of the Luminophore 1 According to the Working Example BaPbF6: Mn
Barium fluoride (BaF2, 175.9 mg, 1.01 mmol), tin(II) chloride (SnCl2, 275.3 mg, 0.99 mmol) and manganese(II) chloride tetrahydrate (MnCl2.4H2O, 1.5 mg, 0.01 mmol) are mixed intimately in an agate mortar and introduced into a corundum boat. This corundum boat is placed in a corundum tube heatable by a tubular furnace, through which 10% by volume of F2 in argon is passed at 5 ml/min. The temperature is increased from 30° C. to 100° C. within 5 h, which is maintained for 20 h, before the temperature is increased stepwise by 100° C. (10° C./h, hold time 10 h) up to 400° C. After a hold time of 6 days, the furnace is cooled down to a minimum temperature of 30° C., and the reaction mixture is removed, crushed using a glassy carbon mortar and pestle, and put back in the furnace. The reaction mixture is heated in the furnace at 4° C./min up to 400° C., and the reaction mixture is subjected to heat treatment in a fluorine stream for a further 8 days. The luminophore 1 having the formula BaPbF6:Mn is obtained.
The synthesis is thus a dry high-temperature process, in which it is possible to dispense with the use of hydrofluoric acid solutions. Owing to the sparing solubility of BaF2 in water, and since Mn(IV) does not exist alongside Pb(IV) in aqueous hydrofluoric acid, it is not possible to prepare BaPbF6:Mn by the process in aqueous HF which is otherwise customary in industry for complex fluoride luminophores.
Preparation of the Luminophore 1 According to the Working Example ZnSnF6:Mn
Zinc carbonate (ZnCO3, 252.8 mg, 2.02 mmol), tin(II) chloride dihydrate (SnCl2.2H2O, 442.5 mg, 1.96 mmol) and manganese(II) chloride tetrahydrate (MnCl2.4H2O, 8.0 mg, 0.04 mmol) are mixed intimately in an agate mortar and introduced into a corundum boat. This corundum boat is placed in a corundum tube heatable by a tubular furnace, through which 10% by volume of F2 in argon is passed at 5 ml/min. The temperature is increased from 30° C. to 100° C. within 5 h, which is maintained for 20 h, before the temperature is increased stepwise by 100° C. (10° C./h, hold time 10 h) up to 400° C. After a hold time of 7 days, the furnace is cooled down to a temperature of 30° C., and the reaction mixture is removed, crushed using a glassy carbon mortar and pestle, and put back in the furnace. The reaction mixture is heated in the furnace at 4° C./min up to 400° C., and the reaction mixture is subjected to heat treatment in a fluorine stream for a further 5 days. After cooling in the furnace to a temperature of 30° C., the reaction mixture is removed, crushed using a glassy carbon mortar and pestle, and put back in the furnace. The furnace is heated at 4° C./min up to 400° C., and the reaction mixture is subjected to heat treatment in a fluorine stream for a further 11 days. The luminophore 1 having the formula ZnSnF6:Mn is obtained.
The synthesis is thus a dry high-temperature process, in which it is possible to dispense with the use of hydrofluoric acid solutions.
Preparation of the Luminophore 1 According to the Working Example MgGeF6:Mn
Magnesium fluoride (MgF2, 61.2 mg, 0.98 mmol), germanium(IV) oxide (GeO2, 102.4 mg, 0.98 mmol) and manganese(II) chloride tetrahydrate (MnCl2.4H2O, 4.1 mg, 0.02 mmol) are mixed intimately in an agate mortar and introduced into a corundum boat. This corundum boat is placed in a corundum tube heatable by a tubular furnace, through which 10% by volume of F2 in argon is passed at 5 ml/min. The temperature is increased from 30° C. to 100° C. within 5 h, which is maintained for 20 h, before the temperature is increased stepwise by 100° C. (10° C./h, hold time 10 h) up to 400° C. After a hold time of 7 days, the furnace is cooled down to a temperature of 30° C., and the reaction mixture is removed, crushed using a glassy carbon mortar and pestle, and put back in the furnace. The reaction mixture is heated in the furnace at 4° C./min up to 400° C., and the reaction mixture is subjected to heat treatment in a fluorine stream for a further 5 days. The luminophore 1 having the formula MgGeF6:Mn is obtained.
The synthesis is thus a dry high-temperature process, in which it is possible to dispense with the use of hydrofluoric acid solutions. Owing to the sparing solubility of MgF2 in water, it is not possible to prepare SrSnF6:Mn by the process in aqueous HF which is otherwise customary in industry for complex fluoride luminophores.
Preparation of the Luminophore 1 According to the Working Example CdPbF6: Mn
Cadmium chloride (CdCl2, 91.8 mg, 0.50 mmol), lead(II) chloride (PbCl2, 137.4 mg, 0.49 mmol) and manganese(II) chloride tetrahydrate (MnCl2.4H2O, 3.1 mg, 0.02 mmol) are mixed intimately in an agate mortar and introduced into a corundum boat. This corundum boat is placed in a corundum tube heatable by a tubular furnace, through which 10% by volume of F2 in argon is passed at 5 ml/min. The temperature is increased from 30° C. to 100° C. within 5 h, which is maintained for 20 h, before the temperature is increased stepwise by 100° C. (10° C./h, hold time 10 h) up to 400° C. After a hold time of 6 days, the furnace is cooled down to a temperature of 30° C., and the reaction mixture is removed, crushed using a glassy carbon mortar and pestle, and put back in the furnace. The furnace is heated at 4° C./min up to 400° C., and the reaction mixture is subjected to heat treatment in a fluorine stream for a further 26 days. The luminophore 1 having the formula CdPbF6:Mn is obtained.
The synthesis is thus a dry high-temperature process, in which it is possible to dispense with the use of hydrofluoric acid solutions. Owing to the oxidation of manganese(IV) under acidic conditions to manganese(VII), it is not possible to prepare CdPbF6:Mn by the process in aqueous HF which is otherwise customary in industry for complex fluoride luminophores.
Preparation of the Luminophore 1 According to the Working Example ZnPbF6:Mn
Zinc carbonate (ZnCO3, 63.7 mg, 0.51 mmol), lead(II) chloride (PbCl2, 135.2 mg, 0.49 mmol) and manganese(II) chloride tetrahydrate (MnCl2.4H2O, 2.5 mg, 0.01 mmol) are mixed intimately in an agate mortar and introduced into a corundum boat. This corundum boat is placed in a corundum tube heatable by a tubular furnace, through which 10% by volume of F2 in argon is passed at 5 ml/min. The temperature is increased from 30° C. to 100° C. within 5 h, which is maintained for 20 h, before the temperature is increased stepwise by 100° C. (10° C./h, hold time 10 h) up to 400° C. After a hold time of 6 days, the furnace is cooled down to a temperature of 30° C., and the reaction mixture is removed, crushed using a glassy carbon mortar and pestle, and put back in the furnace. The reaction mixture is heated in the furnace at 4° C./min up to 400° C., and the reaction mixture is subjected to heat treatment in a fluorine stream for a further 7 days. The luminophore 1 having the formula ZnPbF6:Mn is obtained.
The synthesis is thus a dry high-temperature process, in which it is possible to dispense with the use of hydrofluoric acid solutions. Owing to the oxidation of manganese(IV) under acidic conditions to manganese(VII), it is not possible to prepare ZnPbF6:Mn by the process in aqueous HF which is otherwise customary in industry for complex fluoride luminophores.
Preparation of the Luminophore 1 According to the Working Example MgPbF6:Mn
Magnesium fluoride (MgF2, 33.1 mg, 0.53 mmol), lead(II) chloride (PbCl2, 136.3 mg, 0.49 mmol) and manganese(II) chloride tetrahydrate (MnCl2.4H2O, 4.0 mg, 0.02 mmol) are mixed intimately in an agate mortar and introduced into a corundum boat. This corundum boat is placed in a corundum tube heatable by a tubular furnace, through which 10% by volume of F2 in argon is passed at 5 ml/min. The temperature is increased from 30° C. to 100° C. within 5 h, which is maintained for 20 h, before the temperature is increased stepwise by 100° C. (10° C./h, hold time 10 h) up to 400° C. After a hold time of 4 days, the furnace is cooled down to a temperature of 30° C., and the reaction mixture is removed, crushed using a glassy carbon mortar and pestle, and put back in the furnace. The reaction mixture is heated in the furnace at 4° C./min up to 400° C., and the reaction mixture is subjected to heat treatment in a fluorine stream for a further 9 days. The luminophore 1 having the formula MgPbF6:Mn is obtained.
The synthesis is thus a dry high-temperature process, in which it is possible to dispense with the use of hydrofluoric acid solutions. Owing to the sparing solubility of MgF2 in water and since Mn(IV) does not exist alongside Pb(IV) under acidic conditions, it is not possible to prepare ZnPbF6:Mn by the process in aqueous HF which is otherwise customary in industry for complex fluoride luminophores.
Preparation of the Luminophore 1 According to the Working Example CdHfF6:Mn
Cadmium fluoride (CdF2, 151.4 mg, 1.01 mmol) and hafnium(IV) oxide (HfO2, 211.4 mg, 1.00 mmol) are mixed intimately in an agate mortar and introduced into a corundum boat. This corundum boat is placed in a corundum tube heatable by a tubular furnace, through which 10% by volume of F2 in argon is passed at 5 ml/min. The temperature is increased from 30° C. to 100° C. within 5 h, which is maintained for 20 h, before the temperature is increased stepwise by 100° C. (10° C./h, hold time 10 h) up to 400° C. The temperature is maintained for 10 h and then increased to 450° C. within 10 h. After a hold time of 12 days, the furnace is cooled down to a temperature of 30° C., and the reaction mixture is removed, crushed using a glassy carbon mortar and pestle, and put back in the furnace. The furnace is heated at 4° C./min up to 450° C., and the reaction mixture is subjected to heat treatment in a fluorine stream for a further 13 days. The luminophore 1 having the formula CdHfF6:Mn is obtained. The input of manganese ions is attributable to previous reactions and a manganese species that has remained as a result, which reacts at the synthesis temperature to give volatile manganese(IV) fluoride and is deposited on the CdHfF6.
The synthesis is thus a dry high-temperature process, in which it is possible to dispense with the use of hydrofluoric acid solutions.
Preparation of the Luminophore 1 According to the Working Example ZnZrF6:Mn
Zinc carbonate (ZnCO3, 124.5 mg, 0.99 mmol), zirconyl chloride octahydrate (ZrOCl2.8H2O, 316.0 mg, 0.98 mmol) and manganese(II) chloride tetrahydrate (MnCl2.4H2O, 3.6 mg, 0.02 mmol) are mixed intimately in an agate mortar and introduced into a corundum boat. This corundum boat is placed in a corundum tube heatable by a tubular furnace, through which 10% by volume of F2 in argon is passed at 5 ml/min. The temperature is increased from 30° C. to 100° C. within 5 h, which is maintained for 20 h, before the temperature is increased stepwise by 100° C. (10° C./h, hold time 10 h) up to 400° C. After a hold time of 8 days, the furnace is cooled down to a temperature of 30° C., and the reaction mixture is removed, crushed using a glassy carbon mortar and pestle, and put back in the furnace. The reaction mixture is heated in the furnace at 4° C./min up to 400° C., and the reaction mixture is subjected to heat treatment in a fluorine stream for a further 10 days. The luminophore 1 having the formula ZnZrF6:Mn is obtained.
The synthesis is thus a dry high-temperature process, in which it is possible to dispense with the use of hydrofluoric acid solutions.
Preparation of the Luminophore 1 According to the Working Example CaSnF6:Mn
Calcium fluoride (CaF2, 154.4 mg, 1.97 mmol), tin(II) chloride dihydrate (SnCl2.2H2O, 446.7 mg, 1.98 mmol) and calcium permanganate tetrahydrate (Ca(MnO4)2.4H2O, 3.0 mg, 0.01 mmol) are mixed intimately in an agate mortar and introduced into a corundum boat. This corundum boat is placed in a corundum tube heatable by a tubular furnace, through which 10% by volume of F2 in argon is passed at 5 ml/min. The temperature is increased from 30° C. to 100° C. within 5 h, which is maintained for 20 h, before the temperature is increased stepwise by 100° C. (10° C./h, hold time 10 h) up to 400° C. After a hold time of 18 days, the furnace is cooled down to a temperature of 30° C., and the reaction mixture is removed, crushed using a glassy carbon mortar and pestle, and put back in the furnace. The reaction mixture is heated in the furnace at 4° C./min up to 400° C., and the reaction mixture is subjected to heat treatment in a fluorine stream for a further 13 days. The luminophore 1 having the formula CaSnF6:Mn is obtained.
The synthesis is thus a dry high-temperature process, in which it is possible to dispense with the use of hydrofluoric acid solutions. Owing to the sparing solubility of CaF2 in water, it is not possible to prepare CaZrF6:Mn by the process in aqueous HF which is otherwise customary in industry for complex fluoride luminophores.
A conversion element 8 is disposed in the beam path of the primary radiation emitted by the semiconductor chip 6. The conversion element 8 is set up to absorb the primary radiation and convert it at least partly to a secondary radiation having a second wavelength range. In particular, the secondary radiation has a longer wavelength than the primary radiation absorbed.
The conversion element 8 includes a luminophore 1 having the general formula AzEeX6:RE. More particularly, the conversion element 8 may include the luminophore 1 having the formula CaZrF6:Mn, CaHfF6:Mn, SrTiF6:Mn, ZnHfF6:Mn, CaGeF6:Mn, CaPbF6:Mn, SrSnF6:Mn, BaPbF6:Mn, ZnSnF6:Mn, MgGeF6:Mn, CdPbF6:Mn, ZnPbF6:Mn, MgPbF6:Mn, CdHfF6:Mn, CaSnF6:Mn and/or ZnZrF6:Mn. The luminophore 1 may be embedded into a matrix material. The matrix material is, for example, a silicone, a polysiloxane, an epoxy resin or glass. Alternatively, the conversion element 8 may be free of any matrix material. In that case, the conversion element 8 may consist of the luminophore 1, for example of a ceramic of the luminophore 1.
Alternatively, the conversion element 8 may include a second luminophore that converts primary radiation, for example to yellow or green secondary radiation. The combination of the blue primary radiation, the red secondary radiation and the yellow or green secondary radiation can generate warm white mixed light having a high color rendering index Ra.
In the working example shown in
More particularly, the recess 10 is filled completely with the encapsulant 11, and the semiconductor chip 6 and the conversion element 8 are fully enveloped by the encapsulant 11.
The conversion element 8 may, as shown in
In the working example shown in
In the working example shown in
In
Table 3 compares the optical data of the simulated LED emission spectrum with the luminophores of the working examples CaZrF6:Mn and CaHfF6:Mn and of the comparative example K2SiF6:Mn as red luminophore. The second luminophore was assumed to be a green-emitting luminophore (Lu,Y)3Al5O12:Ce, and the semiconductor chip 6 was assumed to be a blue-emitting semiconductor chip 6 having a dominant wavelength λD of 455 nm.
By comparison with the comparative example with the red-emitting luminophore K2SiF6:Mn, the LEDs with the red-emitting luminophore 1 according to the working example CaZrF6:Mn or with the red-emitting luminophore 1 according to the working example CaHfF6:Mn have a higher luminous efficacy of radiation (LER) by 2%. In addition, for the same color locus, i.e. identical CIE x and CIE y, it is possible to achieve a color rendering index Ra which is three points better. Especially in the case of the R9, which is a measure of the true rendering of saturated red hues, a much higher value is observed.
The features and working examples described in conjunction with the figures may be combined with one another in further working examples, even though not all combinations are described explicitly. In addition, working examples described in conjunction with the figures may alternatively or additionally have further features according to the description in the general part.
The invention is not limited to the working examples by the description with reference thereto. Instead, the invention encompasses any new feature and any combination of features, which especially include any combination of features in the claims, even if this feature of this combination itself is not explicitly specified in the claims or working examples.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2020 203 329.3 | Mar 2020 | DE | national |
The present application is a national stage entry according to 35 U.S.C. § 371 of PCT application No.: PCT/EP2021/056526 filed on Mar. 15, 2021; which claims priority to German patent application DE 10 2020 203 329.3, filed on Mar. 16, 2020; all of which are incorporated herein by reference in their entirety and for all purposes.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/056526 | 3/15/2021 | WO |
