Patent Application
20170275532
The present invention relates to a fluorescent material and a manufacturing method thereof. The fluorescent material may be in combination with a plurality of matrix red-emitting phosphor powder to produce a photo-luminescent composition for white LED, mainly used in the field of illumination for white LED.
In the 1990s, the breakthrough in technology and industrialization of blue LED greatly promoted and realized the development of white light-emitting diodes (WLED).
In general, there have been three major categories of illumination source, such as incandescent bulbs, ordinary and compact fluorescent lamps, and high-pressure gas discharge lamps. A light-emitting diode (LED) is a new solid illumination source, wherein the semiconductor compound InGaN-based white LED has many advantages: high luminous efficiency, low heat, energy saving, stable performance, not easily damaged, long lifetime (up to 50,000 hours), environmental friendliness, no radiation, instant start, short response time, strong practicality, small bulk, compact structure, easy to implement large area arrays, etc.
The realization approach of white LED can be divided into the following three categories:
The red, green, and blue tri-phosphor chips are assembled into a white LED. This method has the characteristics of high efficiency, controllable color temperature, and good color rendering index. As a result of the disadvantages of the unstable color temperature due to different light decay of tri-phosphor, complex electric circuit, and higher costs, the commercial practicability is not strong.
(2) Under n-UV (˜395 nm) Chip Excitation:
In recent years, with the development of semiconductor technology and manufacturing process, the luminous band of LED chips shifted to short wave. The current wavelength range of InGaN mainly covers the region from 350 nm to 420 nm (nUV-LED), and a shorter wavelength range (UV-LED 300-350 nm) has been reported, which enlarges the excitation wavelength range of phosphor powder matched with the chip. The red, green, and blue phosphor powders are excited by the high brightness near-ultraviolet LED and respectively produce the corresponding color of light then combined into white light, but there are still some difficulties in its current commercialization.
This white light system comprising the blue LED and yellow phosphor powder has the advantages of high efficiency, simple preparation, and good temperature stability, and it is the white LED system first to be studied and has been practical. The luminescence mechanisms for this system is that, when the forward DC voltage of 3˜5V is applied across the both ends of GaN/InGaN diode, some of the blue light (455˜475 nm) emitted from semiconductor chip excites the yttrium-aluminum garnet (Y—Al garnet) YAG:Ce3+ phosphor powder coated on the chip surface and activated by Ce3+ to make it emit yellow light (emission peak being at 555 nm). And then, the yellow light will blend with not absorbable blue light to create the white light. However, its drawback is the poor color rendering index caused by the lack of right light.
The white fluorescent efficiency depends on the matrix of the phosphor powder used, which may be silicates, sulfates, phosphates, oxides, aluminates, nitrides, and oxide-nitrides of phosphor powder or mixtures thereof. As compared with those above, under blue light excitation, the fluorescent material based on Y—Al garnet activated by Ce has the advantages of relatively high absorption efficiency, good thermal stability, high quantum efficiency, broad emission spectrum band, etc.
A yellow fluorescent material having a formula (Y1−xCex)3Al5O12 (abbr: YAG), i.e., a Y—Al garnet structure, is disclosed in U.S. Pat. No. 5,999,925 to Nichia Chemical Corporation. It can be combined with blue LED to generate white LED. This synthesized white LED has been applied in the field of white LED illumination in the commercial market, owing to the low cost and high luminous efficiency. However, its disadvantages are the poor color rendering index, the large influence of coating thickness on white light, and poor uniformity.
Kummer et al., U.S. Pat. No. 6,669,866, based on the above United States patent, replaces Y3+ with Tb3+ and proposes a fluorescent material having a formula (Tb1−x−yRexCey)3(Al,Ga)5O12 (abbreviated TAG), known as Tb—Al garnet. However, because its luminous efficiency is still difficult to catch up with YAG fluorescent powder and the cost of terbium is quite expensive, the application of TAG phosphor powder is difficult.
A fluorescent material having a formula R(3−x−y)M5O12:Cex,R′y, is disclosed in the patent CN: ZL02130949.3 by “Grirem Advanced Material Co. Ltd.”, wherein R is at least one element of Y, Gd, Lu, Sc, La, and Sm, M is at least one element of B, Al, Ga, In, P, Ge, and Zn, and R′ is at least one element of Tb, Eu, Dy, Pr, and Mn. Additionally, “Grirem Advanced Material Co. Ltd.” discloses further in the patent application CN: 1544575A using as a few divalent metal elements instead of aluminum or yttrium in white LED phosphor powder containing boron, by which in a certain extent luminous conversion efficiency and stability thereof are improved, thus the quantum efficiency and brightness thereof are also increased. Although the color rendering index of this phosphor powder has been improved compared with the foregoing YAG phosphor powder, the blue conversion efficiency and brightness are still low.
Ce acts as a luminescence activator in Y—Al garnet structure phosphor powder, and the energy level transitions of the atom thereof in matrix define the fluorescence color. The concentration of Ce decides the fluorescence brightness (the correlation function can also be achieved by praseodymium (Pr) and ytterbium (Yb)).
The elements Gd, Tb, La, Lu, and Sm acting as a sensitizer are responsible for shifting the wave peak of the fluorescence spectrum toward longer (Gd, Tb) or shorter (La, Lu, and Sm) waves.
The object of the present invention is, in view of the shortcomings of the prior art, to provide a novel halogen co-activated aluminate which has the advantages of high brightness, high color rendering index, strong stability, low light decay, etc.
Based on the prior art references, the present invention shows that the halogen substitutes for oxygen form a charged center, and then the addition of charge compensators may substantially make the fluorescent material achieve charge balance. In the present case, it is called the charge compensation principle. A benefit to performing this compensation step is to increase the luminous intensity of the phosphor powder.
AlF3, CaF2, MgF2, BaF2, BaCl2, SrF2, and ZnCl2 containing the co-activator halogen element F or Cl also act as a fluxing agent.
Owing to the introduction of the fluxing agent, the synthesis temperature of the fluorescent material in the present invention shows a decrease from 1600° C. down to about 1370° C., which is of great significance for reducing costs.
The halogen co-activated aluminate fluorescent material of the present invention has a wider spectral coverage (526 nm to 580 nm), a higher luminous intensity (enhanced about 15 percent), and lower cost than the commonly used traditional luminescent material. A white LED photo-luminescent composition having high luminous efficiency, high color rendering index (Ra can reach 87 or even higher), low color temperature, and high stability can be obtained by combining the fluorescent material in the present invention and the nitride red-emitting phosphor powder.
One aspect of the present invention provides a fluorescent material, characterized in that the fluorescent material comprises a compound having a general formula I:
[Lu1−a−c−d−2/3bYaΣ(Ln−1)cΣ(Ln−2)dMb]3±δ[Al1−xGax]5(O1−1/2yXy)12±1.5δ (I)
in which:
M is at least one element selected from the group consisting of Ca, Mg, Ba, Sr, and Zn;
b=0.5y(12±1.5δ), 0≦b≦0.2;
0.001≦a≦0.95;
0≦x≦0.5;
Σ(Ln−1) represents at least one element of La, Gd, Tb, Nd, and Ho, and 0≦c≦0.9;
Σ(Ln−2) represents an activator and is at least one element selected from the group consisting of Ce, Pr, Dy, Eu, Tm, Er, Sm, Yb, and Sc, and 0.001≦d≦0.5;
X represents a co-activator, which is at least one element selected from the group consisting of F and Cl, and 0.001≦y≦0.2;
1−a−c−d≧0; and
0<δ≦1.5.
One aspect of the present invention provides a fluorescent material, characterized in that the fluorescent material comprises a compound having a general formula I:
[Lu1−a−c−d−2/3bYaΣ(Ln−1)cΣ(Ln−2)dMb]3εδ[Al1−xGax]5(O1−1/2yXy)12±1.5δ (I)
in which
M is at least one element selected from the group consisting of Ca, Mg, Ba, Sr, and Zn;
(1−a−c−d−2/3b+a+c+d)(3±δ)≠3, 0≦b≦0.2;
0.001≦a≦0.95;
0≦x≦0.5;
Σ(Ln−1) represents at least one element of La, Gd, Tb, Nd, and Ho, and 0≦c≦0.9;
Σ(Ln−2) represents an activator and is at least one element selected from the group consisting of Ce, Pr, Dy, Eu, Tm, Er, Sm, Yb, and Sc, and 0.001≦d≦0.5;
X represents a co-activator, which is at least one element selected from the group consisting of F and Cl, and 0.001≦y≦0.2;
1−a−c−d≧0; and
0<δ≦1.5.
In some embodiments, the fluorescent material of the present invention comprises a compound having a general formula I-1:
[Lu1−a−c−d−2/3bYaΣ(Ln−1)cΣ(Ln−2)dMb]3−δ[Al1−xGax]5(O1−1/2Xy)12−1.5δ (I- 1)
in which Σ(Ln−2) represents at least one element of Ce and Pr.
In some embodiments, the fluorescent material of the present invention comprises a compound having a general formula I-2:
[Lu1−a−c−d−2/3bYaΣ(Ln−1)cΣ(Ln−2)dMb]3+δ[Al1−xGax]5(O1−1/2yXy)12+1.5δ (I-2)
in which 0≦b<0.2.
In some embodiments, the fluorescent material of the present invention is selected from the group consisting of the following compounds:
[Lu0.4415Y0.45Ce0.05Ba0.0585]2.8Al5(O0.995,F0.01)11.7;
[Y0.7623Gd0.17Ce0.05Ba0.01774]2.884Al5(O0.9985,F0.003)11.826;
[Y0.6323Gd0.29Ce0.06Ba0.01774]2.884Al5(O0.9985,F0.003)11.826;
[Y0.3823Gd0.55Ce0.05Ba0.01774]2.884Al5(O0.9985,F0.003)11.826;
[Lu0.0995Y0.7688Gd0.07Nd0.0005Ce0.05Ba0.01125]2.5(Al4.9Ga0.1)(O0.999,F0.002)11.25; and
[Lu0.0995Y0.77Gd0.07Nd0.0005Ce0.05Ba0.01]1.67(Al4.9Ga0.1)(O0.999,F0.002)10.005.
In some embodiments, the fluorescent material of the present invention is selected from the group consisting of following compounds:
[Y0.8829Gd0.005Ce0.05Ba0.0621]3.28Al5(O0.995,F0.01)12.42;
[Lu0.4812Y0.45Ce0.05Ba0.0188]3.35Al5(O0.9985,F0.003)12.525;
[Lu0.5812Y0.35Ce0.05Ba0.0188]3.35Al5(O0.9985,F0.003)12.525;
[Lu0.7312Y0.2Ce0.05Ba0.0188]3.35Al5(O0.9985,F0.003)12.525;
[Y0.9262Ce0.055Ba0.0188]3.35Al4.5Ga0.5(O0.9985,F0.003)12.525;
[Y0.9262Ce0.055Ba0.0188]3.35Al4.0Ga1.0(O0.9985,F0.003)12.525;
[Y0.9262Ce0.055Ba0.0188]3.35Al3.5Ga1.5(O0.9985,F0.003)12.525;
[Y0.9262Ce0.055Ba0.0188]3.35Al3.0Ga2.0(O0.9985,F0.003)12.525; and
[Y0.9262Ce0.055Ba0.0188]3.35Al2.79Ga2.21(O0.9985,F0.003)12.525.
One aspect of the present invention provides a method for preparing the fluorescent material, comprising:
mixing yttrium oxide, cerium oxide, aluminium oxide or aluminium hydroxide, gadolinium oxide, gallium oxide, lutetium oxide, neodymium oxide, aluminum fluoride, barium fluoride uniformly to form a mixture, in which the amounts of yttrium oxide, cerium oxide, aluminium oxide or aluminium hydroxide, gadolinium oxide, gallium oxide, lutetium oxide, neodymium oxide are weighed according to the molar ratios of the metal elements of the phosphor according to the compounds set forth in the specification herein, while aluminium oxide or aluminium hydroxide is added in an amount in excess of 2 percent by weight, barium fluoride is added in an amount of from 2 to 4.5 percent by weight of all oxides, and aluminum fluoride is added in an amount of less than 1 percent; and
roasting the mixture at a temperature of 1330° C. to 1580° C. under a reducing atmosphere of a nitrogen-hydrogen mixed gas or a carbon reducing atmosphere for from 5 to 7 hours.
In some embodiments, said roasting is undertaken at a temperature of 1426° C. for 5 hours under a carbon reducing atmosphere.
One aspect of the present invention provides a photo-luminescent composition comprising:
the present invention fluorescent material; and
a red-emitting phosphor, such as a red-emitting phosphor powder, wherein the weight ratio of the fluorescent material and the red-emitting phosphor is from about 88%:12% to 92%:8%.
In some embodiments, the weight ratio of the fluorescent material and the red-emitting phosphor is about 90%:10%.
In some embodiments, said red-emitting phosphor is selected from the group consisting of nitrides and silicates.
In some embodiments, the red-emitting phosphor is a nitride having a general formula of SrAlSiN3:Eu2+.
In some embodiments, the red-emitting phosphor is a silicate having a general formula of (Sr,Ba)1.88SiO4:Eu2+.
In some embodiments, the fluorescent material of the present invention is [Lu0.4415Y0.45Ce0.05Ba0.0585]2.8Al5(O0.995,F0.01)11.7.
In some embodiments, the fluorescent material of the present invention comprises a compound having a general formula I-1-1:
[Ya,Gdc,Σ(Ln−2)dMb]2.884(Al1−xGax)5(O1−1/2yXy)11.826 (I-1-1).
In some embodiments, the fluorescent material of the present invention comprises a compound having a general formula I-2:
[Lu1−a−c−d−2/3bYaΣ(Ln−1)cΣ(Ln−2)dMb]3+δ[Al1−xGax]5(O1−1/2yXy)12+1.5δ (I-2)
in which 3<3+δ≦4.5, 0.001≦a≦0.95, 0≦b≦0.2, 0≦x≦0.5;
Σ(Ln−1) represents at least one element of La, Gd, Tb, Nd, and Ho, and 0≦c≦0.9;
Σ(Ln−2) represents at least one element of Ce, Pr, Dy, Eu, Tm, Er, Sm, Yb, and Sc, and 0.001≦d≦0.5; and
X represents at least one element selected from F and Cl, and 0.001≦y≦0.2.
In some embodiments, the fluorescent material of the present invention comprises a compound having a general formula I-2-1:
[Lu1−a−c−d−2/3bYaΣ(Ln−1)cΣ(Ln−2)dMb]3.35[Al1−xGax]5(O1−1/2yXy)12.525 (I-2-1).
In some embodiments, the fluorescent material for use in white LED in the present invention offers an luminescent characteristic of the Ce activator, which forms a broad emission band at a yellow-green zone peak of 525 nm to 583 nm.
In some embodiments, the fluorescent material for use in white LED in the present invention offers a luminescent characteristic that the emission peak will be blue-shift as the varying of the ratio between Al and Ga.
In some embodiments, the fluorescent material for use in white LED in the present invention offers a characteristic that it can be excited by a UV to blue light with wavelengths ranging from 250 nm to 490 nm.
In some embodiments, the fluorescent material for use in white LED in the present invention offers a characteristic, which emits a visible area ranging from 450 nm to 700 nm, as well as the peak is located at 525 nm to 610 nm.
Obviously, according to the general formula proposed by the present invention, the value of (3±δ) varies in the range between 1.5 and 4.5, both inclusive, which is not equal to 3. Therefore, it goes beyond the known classic YAl garnet fluorescent powder patent solution belonging to non-stoichiometric compounds.
The present invention provides a method for preparing a fluorescent material for a white LED, the method comprising the steps of:
(1) providing the starting materials comprising oxides of Y2O3, CeO2, Ln−1, oxides of Ln−2, and Ga2O3, Al2O3, AlF3, and BaF2, which are weighed according to the molar ratios specified in the formula:
[Lu1−a−c−d−2/3bYaΣ(Ln−1)cΣ(Ln−2)dMb]3±δ[Al1−xGax]5(O1−1/2yXy)12±1.5δ;
(2) ball milling and mixing uniformly the starting materials mixed in (1) under dry conditions;
(3) roasting the materials mixed uniformly at a temperature of 1330° C. to 1580° C. under a reducing atmosphere for 5 to 7 hours and cooling to obtain a compound comprising (I-1) and (I-2):
[Lu1−a−c−d−2/3bYaΣ(Ln−1)cΣ(Ln−2)dMb]3−δ[Al1−xGax]5(O1−1/2yXy)12−1.5δ,
[Lu1−a−c−d−2/3bYaΣ(Ln−1)cΣ(Ln−2)dMb]3+δ[Al1−xGax]5(O1−1/2yXy)12+1.5δ;
(4) the roasted compound in (3) is ground in a mortar and subjected to a series of post-treatment steps by caustic wash, acid pickling, washing, and alcohol washing to complete the coating; and
(5) drying the product washed in (4) at 140° C. for 16 hours to obtain a phosphor powder having high luminous efficiency, high color rendering index, strong stability, and low light decay.
As described above, the phosphor powder synthesized in the present invention concentrates on the compounds of (Lu+Y+Ln)3±δAl5O12±1.5δ type, wherein the corresponding ratio of
varies from 0.3 to 0.9 when the stoichiometric index (3±δ) varies from 1.5 to 4.5, and unlike the index ratio Y/Al of the conventional Y3Al5O12 compounds being fixed to 0.6, there is a broader range for the index ratio in this present invention.
As is known, alumina and rare earth oxides can form a variety of compounds. For example, in the Y2O3—AlO3 system, in addition to Y3Al5O12, a series of compounds can be formed, and the following series can be formed according to the change in Y—Al content: Y5Al3O12—YAlO3—Y3Al5O12—YAl2O4.5—YAl3O6 [Joint Committee on Powder Diffraction Standards: JCPDS Data Base].
The above series may transform into the following forms Y7.5Al5O18—Y5Al5O15—Y3Al5O12—Y2.5Al5O11.25—Y1.67Al5O10 when the content of Al is a constant value in the molecular formula. On the basis of these compounds, yttrium and aluminum may be replaced by other rare earth elements and Ga, respectively, and the yttrium-doped compound can be synthesized, i.e., the compound of the present invention: [Lu1−a−c−d−2/3bYaΣ(Ln−1)cΣ(Ln−2)dMb]3±δ[Al1−xGax]5(O1−1/2yXy)12±1.5δ.
As far as the inventors know, this type of compound and the proportions thereof have not been demonstrated by others, and the practical application thereof has not been published in the patent literature.
As described above, the fluorescent material for white LED according to the present invention can be excited by a purple light of 250 nm to blue light of 490 nm, or can be combined with any one of a red-emitting phosphor powder of a sulfide, a nitride, and a silicate matrix to form white LED.
The red nitride phosphor powder used in the above white LED can be represented by: SrAlSiN3:Eu2+.
The red silicate phosphor powder used in the above white LED can be represented by: (Sr,Ba)1.88SiO4:Eu2+.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein regarding fluorescent material, a manufacturing method thereof, and a photo-luminescent material containing the fluorescent material, it is nevertheless not intended to be limited to the details shown herein, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
[Lu0.4812Y0.45Ce0.05Ba0.0188]3.35Al5(O0.9985,F0.003)12.5257
[Lu0.5812Y0.35Ce0.05Ba0.0188]3.35Al5(O0.9985,F0.003)12.525, and
[Lu0.7312Y0.2Ce0.05Ba0.0188]3.35Al5(O0.9985,F0.003)12.525.
[Y0.7623Gd0.17Ce0.05Ba0.01774]2.884Al5(O0.9985,F0.003)11.8267
[Y0.6323Gd0.29Ce0.06Ba0.01774]2.884Al5(O0.9985,F0.003)11.826, and
[Y0.3823Gd0.55Ce0.05Ba0.01774]2.884Al5(O0.9985,F0.003)11.826.
[Lu0.0995Y0.7688Gd0.07Nd0.0005Ce0.05Ba0.01125]2.5(Al4.9Ga0.1)(O0.999,F0.002)11.257
[Lu0.0995Y0.77Gd0.07Nd0.0005Ce0.05Ba0.01]1.67(Al4.9Ga0.1)(O0.999,F0.002)10.005.
[Y0.9262Ce0.055Ba0.0188]3.35Al4.5Ga0.5(O0.9985,F0.003)12.525,
[Y0.9262Ce0.055Ba0.0188]3.35Al4.0Ga1.0(O0.9985,F0.003)12.525,
[Y0.9262Ce0.055Ba0.0188]3.35Al3.5Ga1.5(O0.9985,F0.003)12.525,
[Y0.9262Ce0.055Ba0.0188]3.35Al3.0Ga2.0(O0.9985,F0.003)12.525, and
[Y0.9262Ce0.055Ba0.0188]3.35Al2.79Ga2.21(O0.9985,F0.003)12.525.
The phosphor powder prepared has the molecular formula:
[Lu1−a−c−d−2/3bYaΣ(Ln−1)cΣ(Ln−2)dMb]3−δ[Al1-xGax]5(O1−1/2yXy)12−1.5δ
[Lu1−a−c−d−2/3bYaΣ(Ln−1)cΣ(Ln−2)dMb]3+δ[Al1−xGax]5(O1−1/2yXy)12+1.5δ
According to the difference between the stoichiometric index (3±δ) and (12±1.5δ), 15 samples are synthesized using different ratios of rare earth elements and doped aluminum.
As specific examples, data is provided for 15 samples, and the optical properties thereof exhibit a regular change.
The phosphor powder samples shown in the embodiment are prepared by roasting the mixture of Y2O3, rare-earth metals oxides, and Al2O3 at a high temperature. And the particle size (D50) of the starting material used is less than 3 microns (measured by a laser particle size analyzer).
There are many ways to synthesize aluminate as a green-emitting phosphor powder, such as high temperature solid phase method, co-precipitation method, sol-gel method, etc.
In the present invention, a fluorescent material is prepared by a high temperature solid phase method.
Raw materials (yttrium oxide, lanthanide rare earth metal oxides and alumina) dry powder are vibrated and mixed evenly in sealed plastic containers.
The mixture is added with a compound containing a co-activator halogen element and capable of acting as a fluxing agent (e.g., barium fluoride and aluminum fluoride) during the calcination preparation. Its role as a fluxing agent is to form a liquid phase in the solid surface reaction, thereby speeding up the mass transfer rate and the generation speed of the target product. The doping amount of barium fluoride is 2% to 4.5% by weight of the oxide, and the doping amount of the aluminum fluoride is less than 1%.
After the materials above are ground well, they are loaded into a high purity alumina (Al2O3) crucible, gradually heated in a hydrogen-hydrogen reduction (VN2/VH2=3/1) atmosphere or a carbon reducing atmosphere, and roasted at a temperature of 1330° C. to 1580° C. for from 5 to 7 hours and then removed from the furnace when cooled to below 500° C.
Pickling with concentrated nitric acid, then washing with potassium pyrophosphate, washing with water several times to neutral, adding 0.1% lanthanum nitrate, neutralizing with ammonia, filtering, drying in an oven at 140° C. for several hours, washing with isopropyl alcohol, adding 5‰ ethyl orthosilicate, and coating the surface of the powder with a layer of silicon film, results in the production of loose smooth powder, i.e., the fluorescent material of the present invention.
The fluorescent materials obtained by the above method are excited by 460 nm blue light, and the emission peak is located at 537 nm to 578 nm green band.
Proportional amounts of the starting materials are used to meet the stoichiometric requirements of the formula:
[Lu0.4415Y0.45Ce0.05Ba0.0585]2.8Al5(O0.995,F0.01)11.7.
The starting materials Y2O3, Lu2O3, CeO2, Al2O3, AlF3, and BaF2 are roasted under a nitrogen-hydrogen reducing atmosphere (VN2/VH2=3/1) at a temperature of 1337° C. for 5 hours.
The excitation (under the monitoring of 555 nm) and emission (under excitation of 460 nm blue LED) spectra of this fluorescent material having a molecular formula:
[Lu0.4415Y0.45Ce0.05Ba0.0585]2.8Al5(O0.9957,F0.01)11.7
are shown in
Proportional amounts of the starting materials are used to meet the stoichiometric requirements of the formula:
[Y0.8829Gd0.005Ce0.05Ba0.0621]3.28Al5(O0.995,F0.01)12.42.
The starting materials Y2O3, Gd2O3, CeO2, Al2O3, AlF3 and BaF2 are roasted under a carbon reducing atmosphere at a temperature of 1377° C. for 7 hours.
The emission (under excitation of 460 nm blue LED) spectrum of this fluorescent material having a molecular formula:
[Y0.8829Gd0.005Ce0.05Ba0.0621]3.28Al5(O0.995,F0.01)12.42
is shown in
Preparation of fluorescent materials having different ratios of Y to Lu: Proportional amounts of the starting materials are used to meet the stoichiometric requirements of the respective formulas:
[Lu0.4812Y0.45Ce0.05Ba0.0188]3.35Al5(O0.9985,F0.003)12.5257
[Lu0.5812Y0.35Ce0.05Ba0.0188]3.35Al5(O0.9985,F0.003)12.525, and
[Lu0.7312Y0.2Ce0.05Ba0.0188]3.35Al5(O0.99857,F0.003)12.525.
The starting materials Y2O3,Lu2O3,CeO2,Al2O3,AlF3 and BaF2 are roasted under a nitrogen-hydrogen reducing atmosphere (VN2/VH2=3/1) at a temperature of 1512° C. for 5 hours.
The molecular formulas of the fluorescent materials with different ratios of Y to Lu are, respectively:
[Lu0.4812Y0.45Ce0.05Ba0.0188]3.35Al5(O0.9985,F0.003)12.5257
[Lu0.5812Y0.35Ce0.05Ba0.0188]3.35Al5(O0.9985,F0.003)12.525, and
[Lu0.7312Y0.2Ce0.05Ba0.0188]3.35AlO0.9985,F0.003)12.525.
The emission spectrum (under excitation of 460 nm blue LED) of the above fluorescent materials is shown in
Preparation of fluorescent materials having different ratios of Y to Gd: Proportional amounts of the starting materials are used to meet the stoichiometric requirements of the respective formulas:
[Y0.7623Gd0.17Ce0.05Ba0.01774]2.884Al5(O0.9985,F0.003)11.8267
[Y0.6323Gd0.29Ce0.06Ba0.01774]2.884Al5(O0.9985,F0.003)11.826, and
[Y0.3823Gd0.55Ce0.05Ba0.01774]2.884Al5(O0.9985,F0.003)11.826
The starting materials Y2O3,Gd2O3,CeO2,Al2O3,AlF3 and BaF2 are roasted under a carbon reducing atmosphere at a temperature of 1377° C. for 7 hours.
The molecular formulas of the fluorescent materials with different ratios of Y to Lu are, respectively:
[Y0.7623Gd0.17Ce0.05Ba0.01774]2.884Al5(O0.9985,F0.003)11.826,
[Y0.6323Gd0.29Ce0.06Ba0.01774]2.884Al5(O0.9985,F0.003)11.826, and
[Y0.3823Gd0.55Ce0.05Ba0.01774]2.884Al5(O0.9985,F0.003)11.826.
The excitation spectrum (under monitoring of 564 nm, 572 nm and 578 nm, respectively) of the above fluorescent materials is shown in
Proportional amounts of the starting materials are used to meet the stoichiometric requirements of the formula:
[Lu0.0995Y0.7688Gd0.07Nd0.0005Ce0.05Ba0.01125]2.5(Al4.9Ga0.1)(O0.999,F0.002)11.25
The starting materials Y2O3, Lu2O3,Gd2O3,CeO2,Nd2O3,Al2O3,Ga2O3,AlF3 and BaF2, are roasted under a nitrogen-hydrogen reducing atmosphere (VN2/VH2=3/1) at a temperature of 1550° C. for 5 hours.
Proportional amounts of the starting materials are used to meet the stoichiometric requirements of the formula:
[Lu0.0995Y0.77Gd0.07Nd0.0005Ce0.05Ba0.01]1.67(Al4.9Ga0.1)(O0.999,F0.002)10.005.
The starting materials and thermal conditions are the same with example 5.
The emission spectrum (under excitation of 460 nm blue LED) of the fluorescent materials having different ratios of (3−δ) is shown in
[Lu0.0995Y0.7688Gd0.07Nd0.0005Ce0.05Ba0.01125]2.5(Al4.9Ga0.1)(O0.999,F0.002)11.25,
[Lu0.0995Y0.77Gd0.07Nd0.0005Ce0.05Ba0.01]1.67(Al4.9Ga0.1)(O0.999,F0.002)10.005.
Preparation of fluorescent materials having different ratios of Al to Ga: Proportional amounts of the starting materials are used to meet the stoichiometric requirements of the respective formulas:
[Y0.9262Ce0.055Ba0.0188]3.35Al4.5Ga0.5(O0.9985,F0.003)12.525,
[Y0.9262Ce0.055Ba0.0188]3.35Al4.0Ga1.0(O0.9985,F0.003)12.525,
[Y0.9262Ce0.055Ba0.0188]3.35Al3.5Ga1.5(O0.9985,F0.003)12.525,
[Y0.9262Ce0.055Ba0.0188]3.35Al3.0Ga2.0(O0.9985,F0.003)12.525, and
[Y0.9262Ce0.055Ba0.0188]3.35Al2.79Ga2.21(O0.9985,F0.003)12.525.
The starting materials Y2O3, CeO2, Al2O3, Ga2O3, AlF3, and BaF2 are roasted under a carbon reducing atmosphere at a temperature of 1426° C. for 5 hours.
The molecular formulas of the fluorescent materials with different ratios of Al to Ga are, respectively:
[Y0.9262Ce0.055Ba0.0188]3.35Al4.5Ga0.5(O0.9985,F0.003)12.525,
[Y0.9262Ce0.055Ba0.0188]3.35Al4.0Ga1.0(O0.9985,F0.003)12.525,
[Y0.9262Ce0.055Ba0.0188]3.35Al3.5Ga1.5(O0.9985,F0.003)12.525,
[Y0.9262Ce0.055Ba0.0188]3.35Al3.0Ga2.0(O0.9985,F0.003)12.525, and
[Y0.9262Ce0.055Ba0.0188]3.35Al2.79Ga2.21(O0.9985,F0.003)12.525.
The emission spectrum (under excitation of 460 nm blue LED) of the above fluorescent materials is shown in
A white LED photo-luminescent composition is prepared by the combination of fluorescent material [Lu0.4415Y0.45Ce0.05Ba0.0585]2.8Al5(O0.995, F0.01)11.7 prepared in example 1 and nitride red-emitting phosphor powder SrAlSiN3:Eu2+.
A white LED photo-luminescent composition is prepared by combination of the fluorescent material [Lu0.4415Y0.45Ce0.05Ba0.0585]2.8Al5(O0.995,F0.01)11.7 prepared in example 1 and the silicate red-emitting phosphor powder (Sr,Ba)1.88SiO4:Eu2+.
A white LED photo-luminescent composition is prepared by combination of fluorescent material Y3Al5O12:Ce3+ and nitride red-emitting phosphor powder SrAlSiN3:Eu2+.
The photo-luminescent composition formed by the fluorescent material prepared in example 1 with the formula [Lu0.4415Y0.45Ce0.05Ba0.0585]2.8Al5(O0.995,F0.01)11.7 respectively is combined with the red-emitting phosphor powder with a formula SrAlSiN3:Eu2+ or (Sr,Ba)1.88SiO4:Eu2+, as well as the white LED photo-luminescent composition formed by Y3Al5O12:Ce3+ in combination with SrAlSiN3:Eu2+, which are tested in a blue light diode-based solid white light source and the spectra thereof are shown in
Optical property parameters of the samples in the examples are measured, using a HAAS-2000 spectroradiometer, available from Everfine Photo-E-Info Co., Ltd. The yellow-orange fluorescence spectra reflected by samples and radiated by the composite blue light (455 nm) diode are measured, with the angle of reflection of 45° and the wavelength range from 380 nm to 780 nm. The optical characteristics of the fluorescent materials of Examples 1 to 7 are shown in Table 1 below, wherein the sample numbers correspond to the example numbers:
[Lu0.4812Y0.45Ce0.05Ba0.0188]3.35Al5(O0.9985,F0.003)12.525,
[Lu0.5812Y0.35Ce0.05Ba0.0188]3.35Al5(O0.9985,F0.003)12.525, and
[Lu0.7312Y0.2Ce0.05Ba0.0188]3.35Al5(O0.9985,F0.003)12.525.
It can be seen from the figure that the spectrum covers a broadband from 520 nm to 610 nm, moreover, with the decrease of the ratio of Y to Lu, the emission peaks blue shift and positions thereof are located at about 543 nm, 539 nm and 537 nm, respectively.
[Y0.7623Gd0.17Ce0.05Ba0.01774]2.884Al5(O0.9985,F0.003)11.826,
[Y0.6323Gd0.29Ce0.06Ba0.01774]2.884Al5(O0.9985,F0.003)11.826, and
[Y0.3823Gd0.55Ce0.05Ba0.01774]2.884Al5(O0.9985,F0.003)11.826.
As shown in
[Lu0.0995Y0.7688Gd0.07Nd0.0005Ce0.05Ba0.01125]2.5(Al4.9Ga0.1)(O0.999,F0.002)11.25
[Lu0.0995Y0.77Gd0.07Nd0.0005Ce0.05Ba0.01]1.67(Al4.9Ga0.1)(O0.999,F0.002)10.005.
It can be seen from the figure that the emission peaks blue shift with the decrease of the ratio of (3−δ), and the positions thereof are located at 562 nm and 555 nm, respectively.
[Y0.9262Ce0.055Ba0.0188]3.35Al4.5Ga0.5(O0.9985,F0.003)12.525,
[Y0.9262Ce0.055Ba0.0188]3.35Al4.0Ga1.0(O0.9985,F0.003)12.525,
[Y0.9262Ce0.055Ba0.0188]3.35Al3.5Ga1.5(O0.9985,F0.003)12.525,
[Y0.9262Ce0.055Ba0.0188]3.35Al3.0Ga2.0(O0.9985,F0.003)12.525, and
[Y0.9262Ce0.055Ba0.0188]3.35Al2.79Ga2.21(O0.9985,F0.003)12.525.
It can be seen from the figure that the emission peaks blue shift with the decrease of the ratio of Al to Ga, and the positions thereof are located at 549 nm, 540 nm, 535 nm, and 555 nm, respectively.
Thus, the results above indicated that, as varying the ratio of the stoichiometric index (3±δ) from 1.0 to 3.35, the optical characteristics of the samples do not change significantly. Wherein, as varying the ratio of the stoichiometric index (3±δ) from 1.0 to 2.884, the emission peaks slightly red shift, the corresponding color coordinates increase a little, and the color temperatures decrease faintly.
As varying the ratio of the stoichiometric index (3±δ) from 2.89 to 3.35, the emission peaks slightly blue shift, the corresponding color coordinates decrease a little, and the color temperatures increase faintly.
It has been demonstrated that fluorescent materials having the general formula: [Lu1−a−c−d−2/3bYaZ(Ln−1)cΣ(Ln−2)dMb]3±δ[Al1−xGax]5(O1−1/2yXy)12±1.5δ can be synthesized, which materials may be combined with nitride or silicate red-emitting phosphor powder to produce a white LED photo-luminescent composition with high luminous efficiency, high color rendering index, low light decay, and low color temperature. This product has a very important practical significance.
Although the disclosure has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.
All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present disclosure. To the extent that section headings are used, they should not be construed as necessarily limiting.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201410593556.6 | Oct 2014 | CN | national |
This patent application is a continuation-in-part application, under 35 U.S.C. §120, of copending International Patent Application No. PCT/CN2015/000019, filed Jan. 8, 2015, which is in turn based upon and claims the benefit of the filing date, under 35 U.S.C. §119, of Chinese Patent Application No. 201410593556.6, filed Oct. 29, 2014, each of the prior patent applications being incorporated herein by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CN2015/000019 | Jan 2015 | US |
| Child | 15498524 | US |
