Patent Application
20240270597
Materials which rapidly conduct oxygen are useful for a variety of devices such as solid-oxide fuel cells, gas sensors, catalysts, and oxygen separation membranes. However, fast oxygen conductor materials are concentrated in only a handful of materials families, including perovskites, fluorites, Ruddlesden-Poppers, and apatites. Of these, even fewer are known to conduct oxygen via an interstitial-mediated mechanism. Only some Ruddlesden-Popper materials, some apatites, and UO2+x are known to exhibit significant interstitial oxygen ion transport.
The present disclosure is based, at least in part, on the inventors' discovery of new materials exhibiting fast oxygen ion transport, even at low temperatures (e.g., less than 500° C.). Some materials have been found to exhibit oxygen diffusivities sufficiently fast to enable rapid oxygen ion transport at room temperature. As such, the present materials may be used to transport oxygen ions in a variety of devices, e.g., fuel cells, supercapacitors, gas sensors, separation systems, catalysts, metal-air batteries, and steam reactors.
Devices are provided, which in embodiments, comprise a source configured to generate oxygen ions via a redox reaction; and an oxygen ion transport material through which oxygen ions generated from the source are transported. The oxygen ion transport material may have either: Formula I Ax+B2y+C4z+O12 2− wherein x+2y+4z=24 and (x, y, z) is (4, 2, 4), (x, y, z) is (2, 1, 5), or (x, y, z) is (3, 2.5, 4); Formula II A4x+B5y+C4z+O222− wherein 4x+5y+4z=44 and (x, y, z) is (2, 4, 4) or (x, y, z) is (3, 3.2, 4) or (x, y, z) is (2.5, 3.6, 4); or Formula III Bi2MO4X; wherein A, B, and C are independently selected from alkali metals, alkaline earth metals, transition metals, post-transition metals, metalloids, lanthanoids, P, Th, and combinations thereof, and wherein M is selected from rare earth elements and combinations thereof and X is selected from halogens and combinations thereof.
Methods of using the devices are also provided, which in embodiments, which comprise transporting oxygen ions generated from the source through the oxygen ion transport material.
Other principal features and advantages of the disclosure will become apparent to those skilled in the art upon review of the following drawings, the detailed description, and the appended claims.
Illustrative embodiments of the disclosure will hereafter be described with reference to the accompanying drawings.
Provided are oxygen ion transport materials, devices comprising the materials, and methods of using the materials and devices.
AB2C4O12 Materials
Embodiments of the oxygen ion transport materials have Formula I Ax+B2y+C4z+O122− wherein x+2y+4z=24. The labels A, B, and C, represent distinct lattice sites in the material which are occupied by various elements. The A-site elements, B-site elements, and C-site elements are selected to satisfy the valence equation x+2y+4z=24. In embodiments, the valence configuration (x, y, z) is (4, 2, 4), i.e. A4+B22+C44+O122− (Formula IA). In embodiments, the valence configuration (x, y, z) is (2, 1, 5), i.e., A2+B21+C45+O122− (Formula IB). In embodiments, the valence configuration (x, y, z) is (3, 2.5, 4), i.e., A3+B22.5+C44+O122− (Formula IC). In general, the A-site, B-site, and C-site elements may be selected from alkali metals, alkaline earth metals, transition metals, post-transition metals, metalloids, and lanthanoids. In embodiments, a reactive non-metal such as P may be used, e.g., for a C-site element. Unless otherwise stated, more than one type of element may be present on a particular site. This includes, e.g., having 2, 3, 4, 5, 6, 7, etc. different types of elements on the A-site, the B-site, the C-site, or combinations thereof.
In embodiments, a single type of element is present on the A-site, one or two types of elements are present on the B-site, and a single type of element is present on the C-site. In embodiments, a single type of element is present on the A-site, a single type of element is present on the B-site, and a single type of element is present on the C-site.
Table 1, below, includes embodiments of oxygen ion transport materials having Formulas IA, IB, or IC which may be used. In embodiments, the oxygen ion transport material has Formula IA, wherein A is selected from Ti, Zr, Hf, Ce, Re, Ir, and combinations thereof; B is selected from Mg, Ca, Sr, Ba, Mn, Fe, Co, Ni, Cu, and combinations thereof; and C is selected from Si, Ge, Sn, and combinations thereof. In embodiments, the oxygen ion transport material has Formula IB, wherein A is selected from Mg, Ca, Sr, Ba, Cu, Zn, and combinations thereof; B is selected from Li, Na, K, Rb, Cs, Ag, and combinations thereof; and C is selected from V, Nb, Ta, P, As, Sb, and combinations thereof. In embodiments, the oxygen ion transport material has Formula IC, wherein A is selected from Al, Ga, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and combinations thereof; B is selected from a combination of at least one A-site element and at least one of Mg, Ca, Sr, Ba, Mn, Fe, Co, Ni, Cu, and Zn; and a combination of at least two of Mg, Ca, Sr, Ba, Mn, Fe, Co, Ni, Cu, Zn; and C is selected from Si, Ge, Sn, and combinations thereof.
In embodiments, the oxygen ion transport material has Formula IA, wherein A is selected from Zr, Ce, and combinations thereof; B is selected from Mn, Co, Ni, Cu, and combinations thereof; and C is Ge. In embodiments, the oxygen ion transport material has Formula IA, wherein A is selected from Zr, Ce, and combinations thereof; B is selected from Mn, Co, and combinations thereof; and C is Ge. In embodiments, the oxygen ion transport material has Formula IB, wherein A is selected from Ca, Sr, and combinations thereof; B is selected from Na, K, Rb, Cs, Ag, and combinations thereof; and C is selected from V, P, As, and combinations thereof. In embodiments, the oxygen ion transport material has Formula IC, wherein A is selected from Y, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu, Tb, Ce, Pr, and combinations thereof; B is selected from a combination of at least one A-site element and at least one of Ca, Mn, and Co; and a combination of at least two of Ca, Mn, Fe, Co, Cu, Sc and Zn; and C is Ge. An illustrative list of such species is shown in Table 2, below. The materials of Table 2 have been experimentally synthesized and confirmed to share similar crystal structure (although not necessarily same space group) as ZrMn2Ge4O12 (see
A4B5C4O22 Perrierite-Group and Chevkinite-Group Materials
Embodiments of the oxygen ion transport materials have Formula II A4x+B5y+C4z+O222− wherein 4x +5y+4z=44. As noted above, the labels A, B, and C represent distinct lattice sites in the material occupied by various elements. Here, however, the A-site elements, B-site elements, and C-site elements are selected to satisfy the valence equation 4x+5y+4z=44. In embodiments, the valence configuration (x, y, z) is (2, 4, 4), i.e. A42+B54+C44+O222− (Formula IIA). In embodiments, the valence configuration (x, y, z) is (3, 3.2, 4), i.e., A43+B53.2+C44+O222 (Formula IIB). In embodiments, the valence configuration can be fractional due to the compositional variation on each site, for example (x, y, z) is (2.5, 3.6, 4), i.e., A42.5+B53.6+C44+O222− (Formula IIC). In general, the A-site, B-site, and C-site elements may be selected from alkali metals, alkaline earth metals, transition metals, post-transition metals, metalloids, and lanthanoids. In embodiments, an actinide such as Th may be used, e.g., for an A-site element. Unless otherwise stated, more than one type of element may be present on a particular site. This includes, e.g., having 2, 3, 4, 5, 6, 7, etc. different types of elements on the A-site, the B-site, the C-site, or combinations thereof.
In embodiments, a single type of element is present on the A-site, two or three types of elements are present on the B-site, and a single type of element is present on the C-site. In embodiments, two types of elements are present on the A-site, two to five types of elements are present on the B-site, and a single type of element is present on the C-site. In embodiments, a single type of element is present on the A-site, a single type of element is present on the B-site, and a single type of element is present on the C-site.
Table 3, below, includes embodiments of oxygen ion transport materials having Formulas IIA, IIB, or IIC which may be used. In embodiments, the oxygen ion transport material has Formula IIA, wherein A is selected from Mg, Ca, Sr, Ba, Cu, Zn, and combinations thereof; B is selected from Ti, Zr, Hf, Ce, Re, Ir, and combinations thereof; and C is selected from Si, Ge, Sn, and combinations thereof. In embodiments, the oxygen ion transport material has Formula IIB, wherein A is selected from Al, Ga, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and combinations thereof; B is selected from Mn, Ti, Zr, Hf, V, Fe, Co, Cr, Ru, Ir; and a combination of at least one 2+ element (selected from Fe, Co, Ni, Mg, Ca, Zn, Cu, Mn) and at least one 3+, 4+, or 5+ element (selected from Fe, Co, Ni, Mn, Al, Ga, Ti, Zr, Hf, Cr, Ru, Ir, Ge, V, Nb, W); and C is selected from Si, Ge, Sn, and combinations thereof. In embodiments, the oxygen ion transport material has Formula IIC, wherein A is a combination of at least one 2+ or 1+ element (selected from Mg, Ca, Sr, Ba, Cu, Zn, Na) and at least one 3+ or 4+ element (selected from Al, Ga, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Th, Fe); B is a combination of at least one 2+ element (selected from Fe, Co, Ni, Mg, Ca, Zn, Cu, Mn), and at least one 3+, 4+, or 5+ element (selected from Fe, Co, Ni, Mn, Al, Ga, Ti, Zr, Hf, Cr, Ru, Ir, Ge, V, Nb, W); and C is selected from Si, Ge, Sn, Al, and combinations thereof.
In embodiments, the oxygen ion transport material has Formula IIA, wherein A is Sr; B is selected from Zr, Ti, and combinations thereof; and C is Si. In embodiments, the oxygen ion transport material has Formula IIB, wherein A is selected from La, Pr, Nd, Sm, Ce, and combinations thereof; B is selected from Mn, V, Ti, Zn, Fe, Co, Ni, Al, Nb, Mg, Cr, and combinations thereof; and C is Si. In embodiments, the oxygen ion transport material has Formula IIB, wherein A is selected from La, Nd, and combinations thereof; B is selected from Mn, V, Ti, and combinations thereof; and C is Si. In embodiments, the oxygen ion transport material has Formula IIC, wherein A is Ce or a combination of at least two of Sr, Rare Earth Element (REE: Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu), Fe, Ca, Na, and Th; B is selected from Zr, Ti, Fe, Mg, Mn, Cr, Al, Ga, V, W, Nb and combinations thereof; and C is Si or a combination of Si and Al. An illustrative list of such species is shown in Table 4, below. The materials of Table 4 have been experimentally synthesized and confirmed to share the same crystal structure as La4Mn5Si4O22 (see
Bi2MO4X Materials
Embodiments of the oxygen ion transport materials have Formula III, Bi2MO4X wherein M is selected from Rare Earth Elements and X is selected from halogens. In embodiments, M is selected from Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and combinations thereof and X is selected from F, Cl, Br, I, and combinations thereof. Each of these materials have been experimentally synthesized and confirmed to share the same crystal structure as Bi2LaO4Cl. Unless otherwise stated, more than one type of element M, X may be present on each relevant site as described above. However, in embodiments, a single type of element M is present and a single type of element X is present.
Selection of AB2C4O12 and A4B5C4O22 materials which exhibit desirable oxygen ion transport properties may be guided by the following parameters including free volume, migration hop length, bulk thermodynamic stability, and valence state. These parameters, their calculations, and illustrative numeric values for each are described in the Example, below.
Other parameters to be used to identify AB2C4O12 and A4B5C4O22 materials which exhibit desirable oxygen ion transport properties include the formation energy Ef of the dilute oxygen interstitial ion in the AB2C4O12 or A4B5C4O22 material. Density functional theory (DFT) calculations may be used to determine Ef at a T=300K and Po2=0.2 atm for a particular AB2C4O12 or A4B5C4O22 material as described in the Example, below. In embodiments, the oxygen ion transport material is characterized by an Ef of not more than 1 eV under these conditions. This includes an Ef in a range of from 0 eV to 1 eV and from 0.5 eV to 1 eV.
Other parameters to be used to identify AB2C4O12 and A4B5C4O22 materials which exhibit desirable oxygen ion transport properties include the migration energy Em at a T=300K and Po2=0.2 atm of the oxygen ion in the AB2C4O12 or A4B5C4O22 material. Ab initio molecular dynamics (AIMD) simulations may be used to determine Em under these conditions for a particular AB2C4O12 or A4B5C4O22 material as described in the Example, below. In embodiments, the oxygen ion transport material is characterized by an Em under these conditions of not more than 0.6 eV. This includes an Em of not more than 0.5 eV, not more than 0.4 eV, not more than 0.3 eV, not more than 0.2 eV, not more than 0.1 eV, or 0 eV.
The present oxygen ion transport materials may be characterized by the mechanism by which the oxygen ion diffuses through the material. In embodiments, the diffusion is interstitial-mediated oxygen diffusion, which encompasses both interstitial and interstitialcy oxygen diffusion. (See
The present oxygen ion transport materials may be synthesized by known techniques, such as the solid-state reaction heating techniques and the flux method referenced in the Example, below.
Although the present oxygen ion transport materials themselves are encompassed by the present disclosure, they may be incorporated into a variety of devices, which are also encompassed by the present disclosure. In general, any device comprising a source of oxygen ions may comprise that source, and also, any of the present oxygen ion transport materials in order to facilitate the transport of those oxygen ions within, to, or from the device. Thus, in embodiments, such a device comprises a source configured to generate oxygen ions via a redox reaction and an oxygen ion transport material through which the generated oxygen ions are transported. The source is a component, or a material thereof, in which, or on which (i.e., on a surface thereof), the redox reaction occurs. An illustrative redox reaction is O2+4e−→2O2−, in which molecular oxygen is reduced to two oxygen ions. An illustrative source configured to generate oxygen ions via this reaction is an electrode in electrical communication with a source of electrons, e.g., from a counter electrode. In embodiments, the source and the oxygen ion transport material are different, distinct entities. However, in other embodiments, the oxygen ion transport material itself may also be the source of the oxygen ions. This may be achieved if the oxygen ion transport material is also electrically conductive. Illustrative devices are described below, with reference to
Methods of using any of the present oxygen ion transport materials and devices incorporating the materials are also encompassed by the present disclosure. In general, a method of transporting oxygen ions comprises exposing an embodiment of the present oxygen ion transport materials to a source of oxygen ions, wherein the oxygen ions are transported therethrough. The method may further comprise generating the oxygen ions from the source via a redox reaction. The method may further comprise steps involving the operation of the relevant device, e.g., the fuel cell, the metal-air battery, the gas sensor, the separation system, the supercapacitor, the steam reactor, etc.
Oxide materials were examined using a variety of theoretical calculations as follows. Crystallographic information files (CIF files) from the Material Project databases were used to calculate the free volume, migration hop length, bulk thermodynamic stability, and the valence state of the oxides. By way of illustration, a search approach for interstitial-mediated oxygen diffusion materials is described below.
Voronoi analysis of the geometric structures was used to find the free volume. The shared corners and centers of shared edges of the Voronoi polyhedra were also used as initial guesses for the location of the oxygen interstitial (Oi) site. The distance between the interstitial oxygen site and its nearest neighbors was used as the screening criterion. Specifically, for the distance between Oi and its adjacent atom, subtracted by the ionic radius of the adjacent atom, the screening criterion was such that this distance is not smaller than 0.99 Å (i.e., distance≥0.99 Å) when the adjacent atom is a cation and not smaller than 0.88 A (i.e., distance≥0.88 Å) when the adjacent atom is oxygen, respectively. This criterion was used as a guide to determine if there is sufficient room for an Oi atom in the material. The minimum distance between the oxygen interstitial sites was that this distance is less than or equal to 3 Å (i.e., minimum distance≤3 Å). Energy above convex hull of the oxide materials in the closed system and under air condition, i.e., open system, (300K, 0.2 atm O2) was applied to evaluate the thermodynamic stability. In the closed system, the screening kept cases where the energy above hull was less than or equal to 100 meV/atom (i.e., energy above hull≤100 meV/atom). In the open system, the screening kept cases where the energy above hull was less than or equal to 200 meV/atom (i.e., energy above hull≤200 meV/atom). The valence state of the cations in the oxides was also analyzed and the screening criterion was that the valence state is smaller than its maximum oxidation state for at least one cation. Density functional theory (DFT) calculations were used to calculate the formation energy (Ef) of the interstitial oxygen ion in the oxides. Finally, analysis of the oxygen ion diffusion properties of the oxides was carried out using ab initio molecular dynamics (AIMD) simulation and the nudged elastic band (NEB) method. These methods were used to evaluate the migration energy (Em) of the oxygen ion. The DFT calculation, AIMD simulation and the NEB calculation were performed by the Vienna Ab initio Simulation Package (VASP).
As another illustration, a search approach for vacancy-mediated oxygen diffusion materials is described below. The screening kept cases where the distances between the lattice oxygen sites were used as the screening criterion. Specifically, the nearest lattice oxygen distance was less than or equal to 3 Å (i.e., distance≤3 Å). Screening kept cases where the energy above convex hull of the oxide materials in the closed system was less than or equal to 100 meV/atom (i.e., energy above hull≤100 meV/atom). Then the CIF files were analyzed by the bond-valence method, which provided an estimate of the energy barrier (Eb) for the oxide-ion migration based on the geometry structure and composition of the materials. Screening kept cases where the estimated energy barrier was less than or equal to 1 eV. Finally, the defect formation energy and migration energy of oxygen vacancy with charge state 2+ (V{umlaut over (o)}) were studied at the DFT level.
The results of the theoretical calculations described above were used to arrive at two representative oxygen ion transport materials, ZrMn2Ge4O12 and La4Mn5Si4O22. Table 5 also includes a few other representative oxygen ion transport materials. ZrMn2Ge4O12 is an oxide material with the tetragonal space group P4/nbm (a=b=9.77 Å, c=9.83 Å; α=β=γ=90°. The bulk structure is shown in
La4Mn5Si4O22 is isostructural with the chevkinite and perrierite structures, crystallizes in the monoclinic space group (C2/m (a=11.26 Å, b=7.59 <, c=11.34 Å; α=74°. β=75.6°. γ=68.3°). The La4Mn5Si4O22 material displays sorosilicate Si2O7 groups which separate rutile-like sheets of edge-shared MnO8 octahedra from single, isolated MnO8 octahedra, as shown in
The formation energy of the oxygen interstitial (at ≈2% interstitial concentration) in ZrMn2Ge4O12 and La4Mn5Si4O22 bulk structures were calculated under atmospheric condition (T=300K, Po2=0.2 atm) and are summarized in Table 5. Some calculations were performed for other materials as also shown in Table 5. Formation energies were studied with different DFT exchange and correlation functionals. These functionals consist of the generalized gradient approximation (GGA), GGA with Hubbard U correction (GGA+U), hybrid functional of Heyd, Scuseria and Ernzerhof (HSE06), and the strongly constrained and appropriately normed (SCAN) functional. Negative formation energies indicate that incorporating interstitial oxygen ions into the bulk structures is an energetically favorable process and oxygen interstitial defects are stable in the bulk structure. As noted above, the diffusion behavior of the oxygen ion in the bulk structures was studied by AIMD simulation. The migration pathway of oxygen ions in ZrMn2Ge4O12 showed an interstitialcy (or “kick-out”) mechanism, in which an oxygen interstitial hops to an oxygen lattice site and the lattice oxygen hops to another interstitial site. The complete migration pathway is displayed in
As shown in
Similar theoretical calculations were performed to examine a vacancy-mediated oxygen transport material. The results of the theoretical calculations described above are presented below for the representative oxygen ion transport material Bi2LaO4Cl. Bi2LaO4Cl is a tetragonal structure with space group P4/mmm (a=b=3.99 Å, c=9.28 Å; α=β=γ=90°). The bulk structure is shown in
Oxygen ion transport materials were examined using a variety of experimental techniques as follows. Materials were synthesized using a solid-state reaction or flux method, as appropriate. The resulting synthesized powders were analyzed using X-ray diffraction (XRD) to verify the crystal structure matched to known records and to check for the presence of multiple phases. Powder samples were pressed and sintered at high temperature to achieve dense samples. To assess the presence of interstitial oxygen, dense, sintered samples of the oxygen ion transport materials ZrMn2Ge4O12 and La4Mn5Si4O22, were examined using the electron probe micro-analyzer (EPMA) and iodometric titration methods. The chemical oxygen diffusivity and surface exchange coefficient of ZrMn2Ge4O12, La4Mn5Si4O22, and Bi2LaO4Cl were studied using the electrical conductivity relaxation (ECR) method. Electrical conductivity transient was measured with abrupt oxygen partial pressure change. Electrical conductivity transient was measured at multiple temperature and oxygen partial pressure conditions. Oxygen diffusivity Dchem and surface exchange coefficient Kchem were obtained by fitting the normalized electrical conductivity relaxation curve to the 2-D diffusion equations.
ZrMn2Ge4O12 was synthesized through the solid-state reaction. Stoichiometric quantities of ZrO2, MnCO3, and GeO2 were mixed and grinded using an alumina mortar and pestle for 1 hour. Then the reaction mixture was heated in an alumina crucible with a volume of 30 ml at 1050° C. for 6 hours with lid on. The grinding and heating process was repeated for 9 times and the ZrMn2Ge4O12 powder was obtained. The crystalline structure of ZrMn2Ge4O12 was examined by XRD as shown in
La4Mn5Si4O22 was synthesized through the flux method. Stoichiometric quantities of La2O3, MnO2, and SiO2 were mixed with KCL flux. The flux-to-reactants mass ratio was 1.6:1. The reaction mixture was heated in an alumina crucible with a volume of 30 ml at 900° C. for 6 days with lid on. The sample was slow cooled down to 500° C. at a rate of 20° C./h and then cooled down to room temperature for 5 h at a rate of 95° C./h. The resultant powder was washed with deionized water for 7-10 times to dissolve the KCL flux and dried on a hot plate at 120° C. in air. La4Mn5Si4O22 powder was obtained and examined by XRD as shown in
Bi2LaO4Cl was synthesized through the flux method. Stoichiometric quantities of Bi2O3, BiOCl, and La2O3 were mixed with CsCl flux with 95% molar concentration of the solvent. The reaction mixture was heated in an alumina crucible at 800° C. for 20 h with lid on. The sample was cooled down to room temperature at a cooling rate of 240 ° C./h. After cooling down, the synthesized sample was washed with deionized water for several times to remove the CsCl flux and dried on a hot plate at 120° C. in air. Bi2LaO4Cl powder was obtained and examined by XRD as shown in
Synthesized ZrMn2Ge4O12 powder was pressed and sintered at 1100° C. for 10 h in air and La4Mn5Si4O22 powder was pressed and sintered at 1050° C. for 24 h in air to achieve densification. Electron probe micro-analyser (EPMA) analysis was performed on the polished pellet, and the results are summarized in Table 7. From the EPMA analysis, the derived stoichiometries are ZrMn2.04Ge3.79O12+1.14 and La4Mn4.69Si4.03O22+0.42 respectively, revealing the presence of Ge-vacancy and interstitial oxygen in ZrMn2Ge4O12 and the presence of Mn-vacancy and interstitial oxygen in La4Mn5Si4O22. The presence of the interstitial oxygen validates the use of these compounds as oxygen ion transport materials for use in any of the devices described herein, including supercapacitors (for which capacitive charge storage is related to the oxygen interstitial concentration). Iodometric titration analysis was performed on the polished pellet of nominally La4Mn5Si4O22 and ZrMn2Ge4O12, the derived stoichiometry was La4Mn4.69Si4.03O22+0.47 and ZrMn2.04Ge3.79O12+3.37 by assuming that the stoichiometry of cations is the same with the EPMA results. The existence of interstitial oxygen was confirmed by the EPMA and iodometric titration analysis.
Oxygen diffusivity Dchem and surface exchange coefficient Kchem were obtained by fitting the normalized electrical conductivity relaxation curve to the 2-D diffusion equations. Fitting of the normalized electrical conductivity relaxation curve of ZrMn2Ge4O12 with oxygen partial pressure changing from 5% to 20% at 750° C. is shown in
The word “illustrative” is used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as “illustrative” is not necessarily to be construed as preferred or advantageous over other aspects or designs. Further, for the purposes of this disclosure and unless otherwise specified, “a” or “an” means “one or more.”
Each of the formulas disclosed herein encompass compounds in which the amounts of the elements may deviate from ideal, e.g., non-stoichiometric compounds. This deviation is inherent in the nature of chemical compounds, including the fact that the compounds are capable of allowing for oxygen transport so that some oxygen may be missing as vacancies or additional oxygen may be present during transport. For example, the deviation may be up to about 0.5 in cations. This includes up to about 0.4, up to about 0.3, up to about 0.2, and up to about 0.1. The deviation for oxygen may be, e.g., up to 25% of oxygen missing as oxygen vacancies or up to about 20% additional oxygen as interstitials. As a specific example, the formula ZrMn2Ge4O12 encompasses the measured stoichiometries in Table 7, i.e., ZrMn2.04Ge3.79O12+3.37 and ZrMn2.04Ge3.79O12+1.14. Similarly, the formula La4Mn5Si4O22 encompasses La4Mn4.69Si4.03O22+0.42 and La4Mn4.69Si4.03O22+0.47.
All numeric values of parameters in the present disclosure are proceeded by the term “about” which means approximately. This encompasses those variations inherent to the measurement of the relevant parameter as understood by those of ordinary skill in the art. This also encompasses the exact value of the disclosed numeric value and values that round to the disclosed numeric value.
The foregoing description of illustrative embodiments of the disclosure has been presented for purposes of illustration and of description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the disclosure. The embodiments were chosen and described in order to explain the principles of the disclosure and as practical applications of the disclosure to enable one skilled in the art to utilize the disclosure in various embodiments and with various modifications as suited to the particular use contemplated. It is intended that the scope of the disclosure be defined by the claims appended hereto and their equivalents.
The present application claims priority to U.S. provisional patent application No. 63/210,560 that was filed Jun. 15, 2021, the entire contents of which are incorporated herein by reference.
This invention was made with government support under DE-SC0020419 awarded by the US Department of Energy. The government has certain rights in the invention.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US22/72916 | 6/14/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63210560 | Jun 2021 | US |
