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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on V(PO3)3 by Materials Project

V(PO3)3 crystallizes in the orthorhombic P2_12_12_1 space group. The structure is three-dimensional. V3+ is bonded to six O2- atoms to form VO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of V–O bond distances ranging from 2.01–2.14 Å. There are three inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent VO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 53–56°. There are a spread of P–O bond distances ranging from 1.50–1.64 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent VO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 45–48°. There are a spread of P–O bond distances ranging from 1.51–1.61 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent VO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 40–42°. There are a spread of P–O bond distances ranging from 1.50–1.63 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one V3+ and one P5+ atom. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to one V3+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one V3+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one V3+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one V3+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a bent 120 degrees geometry to one V3+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on V(PO3)3 by Materials Project

V(PO3)3 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are two inequivalent V3+ sites. In the first V3+ site, V3+ is bonded to six O2- atoms to form VO6 octahedra that share corners with six PO4 tetrahedra and an edgeedge with one VO6 octahedra. There are a spread of V–O bond distances ranging from 1.95–2.24 Å. In the second V3+ site, V3+ is bonded to six O2- atoms to form VO6 octahedra that share corners with six PO4 tetrahedra and an edgeedge with one VO6 octahedra. There are a spread of V–O bond distances ranging from 2.00–2.16 Å. There are six inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent VO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 20–51°. There are a spread of P–O bond distances ranging from 1.50–1.63 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three VO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 46–54°. There are a spread of P–O bond distances ranging from 1.50–1.58 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two VO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 42–44°. There are a spread of P–O bond distances ranging from 1.51–1.61 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one VO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedral tilt angles are 40°. There are a spread of P–O bond distances ranging from 1.46–1.66 Å. In the fifth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three VO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 40–57°. There are a spread of P–O bond distances ranging from 1.50–1.59 Å. In the sixth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one VO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedral tilt angles are 16°. There are a spread of P–O bond distances ranging from 1.45–1.66 Å. There are eighteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one V3+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two P5+ atoms. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one V3+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to one V3+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a single-bond geometry to one P5+ atom. In the seventh O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the eighth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the ninth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the tenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two V3+ and one P5+ atom. In the eleventh O2- site, O2- is bonded in a distorted linear geometry to one V3+ and one P5+ atom. In the twelfth O2- site, O2- is bonded in a distorted trigonal planar geometry to two V3+ and one P5+ atom. In the thirteenth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the fourteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one V3+ and one P5+ atom. In the fifteenth O2- site, O2- is bonded in a single-bond geometry to one P5+ atom. In the sixteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one V3+ and one P5+ atom. In the seventeenth O2- site, O2- is bonded in a bent 120 degrees geometry to one V3+ and one P5+ atom. In the eighteenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one V3+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on V(PO3)3 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on V(PO3)3 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on V(PO3)3 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiV(PO3)3 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiV(PO3)3 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiV(PO3)3 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiV(PO3)3 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiV(PO3)3 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiV(PO3)3 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiV(PO3)3 by Materials Project

LiV(PO3)3 crystallizes in the trigonal R3 space group. The structure is three-dimensional. Li1+ is bonded in a distorted T-shaped geometry to three equivalent O2- atoms. All Li–O bond lengths are 2.08 Å. V2+ is bonded to six O2- atoms to form VO6 octahedra that share corners with six equivalent PO4 tetrahedra. There are three shorter (2.15 Å) and three longer (2.20 Å) V–O bond lengths. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent VO6 octahedra and corners with two equivalent PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–58°. There are a spread of P–O bond distances ranging from 1.50–1.63 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to two equivalent P5+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one V2+, and one P5+ atom. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to one V2+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li2V(PO3)5 by Materials Project

Li2V(PO3)5 crystallizes in the monoclinic Pc space group. The structure is three-dimensional. there are two inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded in a 3-coordinate geometry to three O2- atoms. There are a spread of Li–O bond distances ranging from 1.91–1.97 Å. In the second Li1+ site, Li1+ is bonded in a distorted T-shaped geometry to three O2- atoms. There is two shorter (1.89 Å) and one longer (1.94 Å) Li–O bond length. V3+ is bonded to six O2- atoms to form VO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of V–O bond distances ranging from 1.97–2.13 Å. There are five inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.49–1.64 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent VO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 36–41°. There are a spread of P–O bond distances ranging from 1.51–1.61 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.48–1.63 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent VO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 32–42°. There are a spread of P–O bond distances ranging from 1.51–1.61 Å. In the fifth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent VO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 47–48°. There is two shorter (1.50 Å) and two longer (1.63 Å) P–O bond length. There are fifteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one V3+ and one P5+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to one Li1+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one V3+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two P5+ atoms. In the sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one V3+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one V3+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Li1+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one V3+ and one P5+ atom. In the tenth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the eleventh O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the twelfth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the thirteenth O2- site, O2- is bonded in a bent 120 degrees geometry to one Li1+ and one P5+ atom. In the fourteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one V3+ and one P5+ atom. In the fifteenth O2- site, O2- is bonded in a 3-coordinate geometry to two Li1+ and one P5+ atom.

36 MATERIALS SCIENCE↗
NASA NTRS1995

Design of a three-layer antireflection coating for high efficiency indium phosphide solar cells using a chemical oxide as first layer

It is well known that the behavior of III-V compound based solar cells is largely controlled by their surface, since the majority of light generated carriers (63% for GaAs and 79% for InP) are created within 0.2 mu m of the surface of the illuminated cell. Consequently, the always observed high surface recombination velocity (SRV) on these cells is a serious limiting factor for their high efficiency performance, especially for those with p-n junction made by either thermal diffusion or ion implantation. A good surface passivation layer, ideally a grown oxide as opposed to a deposited one, will cause a significant reduction in the SRV without adding interface problems, thus improving the performance of III-V compound based solar cells. Another significant benefit to the overall performance of the solar cells can be achieved by a substantial reduction of their large surface optical reflection by the use of a well designed antireflection (AR) coating. In this paper, we demonstrate the effectiveness of using a chemically grown thermally and chemically stable oxide, not only for surface passivation but also as an integral part of a 3-layer AR coating for thermally diffused p+n InP solar cells. A phosphorus-rich interfacial oxide, In(PO3)3, is grown at the surface of the p+ emitter using an etchant based on HNO3, o-H3PO4 and H2O2. This oxide has the unique properties of passivating the surface as well as serving as an efficient antireflective layer yielding a measured record high AMO open-circuit voltage of 890.3 mV on a thermally diffused InP(Cd,S) solar cell. Unlike conventional single layer AR coatings such as ZnS, Sb2O3, SiO or double layer AR coatings such as ZnS/MgF2 deposited by e-beam or resistive evaporation, this oxide preserves the stoichiometry of the InP surface. We show that it is possible to design a three-layer AR coating for a thermally diffused InP solar cell using the In(PO3)3 grown oxide as the first layer and Al2O3 and MgF2 as the second and third layers respectively, so as to yield an overall theoretical reflectance of less than 2%. Since chemical oxides are readily grown on III-V semiconductors materials, the technique of using the grown oxide layer to both passivate the surface as well as serve as the first of a multilayer AR coating should work well for all III-V compound-based solar cells.

Moulot, Jacques↗
NASA NTRS1995

Design of a Three-Layer Antireflection Coating for High Efficiency Indium Phosphide Solar Cells Using a Chemical Oxide as First Layer

It is well known that the behavior of III-V compound based solar cells is largely controlled by their surface, since the majority of light generated carriers (63% for GaAs and 79% for InP) are created within 0.2 microns of the illuminated surface of the cell. Consequently, the always observed high surface recombination velocity (SRV) on these cells is a serious limiting factor for their high efficiency performance, especially for those with the p-n junction made by either thermal diffusion or ion implantation. A good surface passivation layer, ideally, a grown oxide as opposed to a deposited one, will cause a significant reduction in the SRV without adding interface problems, thus improving the performance of III-V compound based solar cells. Another significant benefit to the overall performance of the solar cells can be achieved by a substantial reduction of their large surface optical reflection by the use of a well designed antireflection (AR) coating. In this paper, we demonstrate the effectiveness of using a chemically grown, thermally and chemically stable oxide, not only for surface passivation but also as an integral part of a 3- layer AR coating for thermally diffused p(+)n InP solar cells. A phosphorus-rich interfacial oxide, In(PO3)3, is grown at the surface of the p(+) emitter using an etchant based on HNO3, o-H3PO4 and H2O2. This oxide has the unique properties of passivating the surface as well as serving as a fairly efficient antireflective layer yielding a measured record high AM0, 25 C, open-circuit voltage of 890.3 mV on a thermally diffused InP(Cd,S) solar cell. Unlike conventional single layer AR coatings such as ZnS, Sb2O3, SiO or double layer AR coatings such as ZnS/MgF2 deposited by e-beam or resistive evaporation, this oxide preserves the stoichiometry of the InP surface. We show that it is possible to design a three-layer AR coating for a thermally diffused InP solar cell using the In(PO3)3 grown oxide as the first layer and Al2O3, MgF2 or ZnS, MgF2 as the second and third layers respectively, so as to yield an overall theoretical reflectance of less than 2%. Since chemical oxides are readily grown on III-V semiconductor materials, the technique of using the grown oxide layer to both passivate the surface as well as serve as the first of a multilayer AR coating, should work well for essentially all III-V compound-based solar cells.

Moulot, Jacques↗
DOE OSTI2020

Materials Data on LiV(PO3)4 by Materials Project

LiV(PO3)4 crystallizes in the monoclinic Cc space group. The structure is three-dimensional. Li1+ is bonded in a 3-coordinate geometry to three O2- atoms. There is two shorter (1.88 Å) and one longer (2.09 Å) Li–O bond length. V3+ is bonded to six O2- atoms to form VO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of V–O bond distances ranging from 2.02–2.07 Å. There are four inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent VO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedral tilt angles are 43°. There are a spread of P–O bond distances ranging from 1.50–1.61 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one VO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedral tilt angles are 59°. There are a spread of P–O bond distances ranging from 1.47–1.62 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one VO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedral tilt angles are 48°. There are a spread of P–O bond distances ranging from 1.48–1.62 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent VO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedral tilt angles are 43°. There are a spread of P–O bond distances ranging from 1.50–1.61 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a linear geometry to one Li1+ and one P5+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one Li1+ and one P5+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two P5+ atoms. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one V3+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one V3+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one V3+, and one P5+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one V3+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the tenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one V3+ and one P5+ atom. In the eleventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one V3+ and one P5+ atom. In the twelfth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li2V(PO3)5 by Materials Project

Li2V(PO3)5 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. Li1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Li–O bond distances ranging from 2.08–2.47 Å. V3+ is bonded to six O2- atoms to form VO6 octahedra that share corners with six PO4 tetrahedra. There are four shorter (2.02 Å) and two longer (2.08 Å) V–O bond lengths. There are three inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent VO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedral tilt angles are 49°. There are a spread of P–O bond distances ranging from 1.51–1.60 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one VO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedral tilt angles are 45°. There are a spread of P–O bond distances ranging from 1.49–1.62 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There is two shorter (1.50 Å) and two longer (1.63 Å) P–O bond length. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Li1+ and one P5+ atom. In the second O2- site, O2- is bonded in a trigonal non-coplanar geometry to two equivalent Li1+ and one P5+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two P5+ atoms. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent P5+ atoms. In the fifth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one V3+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one V3+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two P5+ atoms. In the eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one V3+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Li1+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na3VP3NO9 by Materials Project

Na3V(PO3)3N crystallizes in the cubic P2_13 space group. The structure is three-dimensional. there are three inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 7-coordinate geometry to one N3- and six O2- atoms. The Na–N bond length is 3.06 Å. There are three shorter (2.59 Å) and three longer (2.62 Å) Na–O bond lengths. In the second Na1+ site, Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share corners with six equivalent PNO3 tetrahedra and a faceface with one VO6 octahedra. There are three shorter (2.36 Å) and three longer (2.49 Å) Na–O bond lengths. In the third Na1+ site, Na1+ is bonded in a 3-coordinate geometry to three equivalent O2- atoms. All Na–O bond lengths are 2.40 Å. V3+ is bonded to six O2- atoms to form VO6 octahedra that share corners with six equivalent PNO3 tetrahedra and a faceface with one NaO6 octahedra. There are three shorter (2.02 Å) and three longer (2.03 Å) V–O bond lengths. P5+ is bonded to one N3- and three O2- atoms to form PNO3 tetrahedra that share corners with two equivalent NaO6 octahedra, corners with two equivalent VO6 octahedra, and corners with two equivalent PNO3 tetrahedra. The corner-sharing octahedra tilt angles range from 43–64°. The P–N bond length is 1.74 Å. There are a spread of P–O bond distances ranging from 1.51–1.55 Å. N3- is bonded in a distorted trigonal non-coplanar geometry to one Na1+ and three equivalent P5+ atoms. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+, one V3+, and one P5+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one V3+, and one P5+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to three Na1+ and one P5+ atom.

36 MATERIALS SCIENCE↗