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At least 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Strain to failure measurements of Cr coatings with different processing

Differently processed Cr coatings on Zircaloy cladding were assessed for coating strain to failure. This report includes i) quantification of Cr coating strain to failure for several coating variants, ii) incorporation of high throughput analysis developed utilizing artificial intelligence, and iii) develop a hoop direction coating strain to failure testing approach for high temperatures that doesn’t require digital image correlation strain measurements. Room temperature strain to failure measurements indicated that heat treatment had an impact on strain to failure of the coating, with increasing heat treatment temperature increasing the average strain to failure of the Cr coating.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Mechanical and Thermal Properties of Low-Density Al 20+x Cr 20-x Mo 20-y Ti 20 V 20+y Alloys

Refractory high-entropy alloys (RHEAs) Al 20+x Cr 20-x Mo 20-y Ti 20 V 20+y ((x, y) = (0, 0), (0, 10), and (10, 15)) were computationally studied to obtain a low density and a better mechanical property. The density functional theory (DFT) method was employed to compute the structural and mechanical properties of the alloys, based on a large unit cell model of randomly distributed elements. Debye–Grüneisen theory was used to study the thermal properties of Al 20+x Cr 20-x Mo 20-y Ti 20 V 20+y . The phase diagram calculation shows that all three RHEAs have a single body-centered cubic (BCC) structure at high temperatures ranging from 1000 K to 2000 K. The RHEA Al 30 Cr 10 Mo 5 Ti 20 V 35 has shown a low density of 5.16 g/cm 3 and a hardness of 5.56 GPa. The studied RHEAs could be potential candidates for high-temperature application materials where high hardness, ductility, and low density are required.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Flux effects in precipitation under irradiation simulation of Fe-Cr alloys

Radiation-enhanced precipitation of Cr-rich α’ in irradiated Fe-Cr alloys, which results in hardening and embrittlement, depends on the irradiating particle and the displacement per atom (dpa) rate. Here, we utilize a Cahn-Hilliard phase-field based approach, that includes simple models for nucleation, irradiating particle and rate dependent radiation-enhanced diffusion and cascade mixing to simulate α’ evolution under neutrons, heavy ions, and electron irradiations. Different irradiating particles manifest very different cascade mixing efficiencies. The model was calibrated using neutron data. For cascade inducing neutron/heavy-ion dpa rates at 300 °C between 10-8 and 10-6 dpa/s the model predicts approximately constant number density, decreasing radius, decreasing α’ Cr composition, and lower α’ volume fraction. The model then predicts a dramatic transition to no α’ formation above approximately 10-5 dpa/s, while electron irradiation, with weak mixing, had little effect at dpa rates up to 10-3 dpa/s. These model predictions are consistent with experiments. We explain the results in terms of the flux dependence of the radiation enhanced diffusion, cascade mixing, and their ratio, which all vary significantly in relevant flux ranges for neutron and cascade inducing ion irradiations. These results show that both cascade mixing and radiation enhanced diffusion must be accounted for when attempting to emulate neutron-irradiation effects using accelerated ion irradiations.

Ke, Jia-Hong↗
DOE OSTI2021

Response of CR-39 nuclear track detectors to protons with non-normal incidence

This paper presents data from experiments with protons at non-normal incidence to CR-39 nuclear track detectors, analyzing the properties of detection efficiency, proton track diameter, track contrast, and track eccentricity. Understanding the CR-39 response to protons incident at an angle is important for designing charged particle detectors for inertial confinement fusion (ICF) applications. This study considers protons with incident energies less than 3 MeV. In this regime, an incident angle of 10° has no effect on CR-39 detection efficiency, and >85% detection efficiency is preserved up through 25° in the range of 1.0 MeV–2.1 MeV. For ICF applications, incident angles above 30° are deemed impractical for detector design due to significant drops in proton detection at all energies. We observe significant reductions in detection efficiency compared to theoretical predictions, particularly at low energies where proton tracks are etched away. The proton track diameter measured by the scan system is observed to decrease with higher incident angles. The track diameters are analyzed with two fitting models, and it is shown that the diameter–energy relation can be fit with the existing models at angles up to 30°. The optical contrast of the tracks tends to increase with the angle, meaning that the tracks are fainter, and a larger increase is observed for higher energies. Eccentricity, a measure of how elongated proton tracks are, increases with the incident angle and drops after the critical angle. The lowest energy tracks remain nearly circular even at higher angles.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

Catalyst comprising Pt, Ni, and Cr

Catalysts comprising nanostructured elements comprising microstructured whiskers having an outer surface at least partially covered by a catalyst material comprising at least 90 atomic percent collectively Pt, Ni, and Cr, wherein the Pt is present in a range from 32.4 to 35.8 atomic percent, the Ni is present in a range from 57.7 to 63.7 atomic percent, and the Cr is present in a range from 0.5 to 10.0 atomic percent, and wherein the total atomic percent of Pt, Ni, and Cr equals 100. Catalyst described herein are useful, for example, in fuel cell membrane electrode assemblies.

Steinbach, Andrew J. L.↗
DOE OSTI2020

Materials Data on Cr(PO3)4 by Materials Project

Cr(PO3)4 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Cr4+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Cr–O bond distances ranging from 1.96–2.01 Å. There are two 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 CrO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 43–47°. There are a spread of P–O bond distances ranging from 1.50–1.60 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CrO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedral tilt angles are 42°. There are a spread of P–O bond distances ranging from 1.49–1.62 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Cr4+ and one P5+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent P5+ atoms. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Cr4+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to two equivalent P5+ atoms. In the fifth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cr4+ 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 120 degrees geometry to two P5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cr(PO3)4 by Materials Project

Cr(PO3)4 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. Cr4+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Cr–O bond distances ranging from 1.91–2.00 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 a cornercorner with one CrO6 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 1.47–1.63 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent CrO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 43–49°. There are a spread of P–O bond distances ranging from 1.50–1.60 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent CrO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 44–49°. There are a spread of P–O bond distances ranging from 1.51–1.60 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CrO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedral tilt angles are 47°. There are a spread of P–O bond distances ranging from 1.48–1.63 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cr4+ and one P5+ atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two P5+ atoms. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. 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 distorted bent 150 degrees geometry to one Cr4+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Cr4+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cr4+ and one P5+ atom. In the tenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Cr4+ and one P5+ atom. In the eleventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cr4+ and one P5+ atom. In the twelfth O2- site, O2- is bonded in a single-bond geometry to one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cr(FeSe2)2 by Materials Project

Cr(FeSe2)2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Cr3+ is bonded to six Se2- atoms to form CrSe6 octahedra that share corners with twelve equivalent FeSe6 octahedra, edges with two equivalent CrSe6 octahedra, and faces with two equivalent FeSe6 octahedra. The corner-sharing octahedra tilt angles range from 53–56°. There are two shorter (2.53 Å) and four longer (2.56 Å) Cr–Se bond lengths. Fe+2.50+ is bonded to six Se2- atoms to form FeSe6 octahedra that share corners with six equivalent CrSe6 octahedra, edges with six equivalent FeSe6 octahedra, and a faceface with one CrSe6 octahedra. The corner-sharing octahedra tilt angles range from 53–56°. There are a spread of Fe–Se bond distances ranging from 2.40–2.67 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 5-coordinate geometry to two equivalent Cr3+ and three equivalent Fe+2.50+ atoms. In the second Se2- site, Se2- is bonded in a 4-coordinate geometry to one Cr3+ and three equivalent Fe+2.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cr(GaS2)2 by Materials Project

Cr(GaS2)2 is Spinel structured and crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Cr2+ is bonded to four equivalent S2- atoms to form CrS4 tetrahedra that share corners with twelve equivalent GaS6 octahedra. The corner-sharing octahedral tilt angles are 55°. All Cr–S bond lengths are 2.19 Å. Ga3+ is bonded to six equivalent S2- atoms to form GaS6 octahedra that share corners with six equivalent CrS4 tetrahedra and edges with six equivalent GaS6 octahedra. All Ga–S bond lengths are 2.53 Å. S2- is bonded in a distorted rectangular see-saw-like geometry to one Cr2+ and three equivalent Ga3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cr(FeSe2)2 by Materials Project

Cr(FeSe2)2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. Cr3+ is bonded in a 4-coordinate geometry to four Se2- atoms. There are a spread of Cr–Se bond distances ranging from 2.45–2.51 Å. There are two inequivalent Fe+2.50+ sites. In the first Fe+2.50+ site, Fe+2.50+ is bonded in a distorted pentagonal planar geometry to five Se2- atoms. There are a spread of Fe–Se bond distances ranging from 2.36–2.50 Å. In the second Fe+2.50+ site, Fe+2.50+ is bonded in a distorted pentagonal planar geometry to five Se2- atoms. There are a spread of Fe–Se bond distances ranging from 2.35–2.57 Å. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 3-coordinate geometry to one Cr3+ and two Fe+2.50+ atoms. In the second Se2- site, Se2- is bonded to one Cr3+ and three Fe+2.50+ atoms to form a mixture of distorted edge and corner-sharing SeCrFe3 tetrahedra. In the third Se2- site, Se2- is bonded in a 3-coordinate geometry to one Cr3+ and two Fe+2.50+ atoms. In the fourth Se2- site, Se2- is bonded to one Cr3+ and three Fe+2.50+ atoms to form a mixture of distorted edge and corner-sharing SeCrFe3 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cr(InS2)2 by Materials Project

Cr(InS2)2 is Spinel-like structured and crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. Cr2+ is bonded to six S2- atoms to form CrS6 octahedra that share corners with six equivalent InS4 tetrahedra, edges with two equivalent CrS6 octahedra, and edges with four equivalent InS6 octahedra. There are two shorter (2.45 Å) and four longer (2.48 Å) Cr–S bond lengths. There are two inequivalent In3+ sites. In the first In3+ site, In3+ is bonded to four S2- atoms to form InS4 tetrahedra that share corners with six equivalent CrS6 octahedra and corners with six equivalent InS6 octahedra. The corner-sharing octahedra tilt angles range from 52–67°. There are two shorter (2.58 Å) and two longer (2.60 Å) In–S bond lengths. In the second In3+ site, In3+ is bonded to six S2- atoms to form InS6 octahedra that share corners with six equivalent InS4 tetrahedra, edges with two equivalent InS6 octahedra, and edges with four equivalent CrS6 octahedra. All In–S bond lengths are 2.65 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to one Cr2+ and three In3+ atoms. In the second S2- site, S2- is bonded to two equivalent Cr2+ and two In3+ atoms to form a mixture of distorted corner and edge-sharing SCr2In2 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cr(PO3)4 by Materials Project

Cr(PO3)4 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Cr4+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with six PO4 tetrahedra. There is two shorter (1.98 Å) and four longer (2.00 Å) Cr–O bond length. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CrO6 octahedra and corners with two equivalent PO4 tetrahedra. The corner-sharing octahedral tilt angles are 50°. There are a spread of P–O bond distances ranging from 1.49–1.63 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent CrO6 octahedra and corners with two equivalent PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 28–50°. There is two shorter (1.50 Å) and two longer (1.61 Å) P–O bond length. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cr4+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cr4+ 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 150 degrees geometry to two P5+ atoms. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to one Cr4+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a single-bond geometry to one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cr(PO3)4 by Materials Project

Cr(PO3)4 crystallizes in the orthorhombic Pbcn space group. The structure is three-dimensional. Cr4+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Cr–O bond distances ranging from 1.92–1.99 Å. There are two 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 CrO6 octahedra and corners with two equivalent PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 44–45°. There are a spread of P–O bond distances ranging from 1.51–1.59 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CrO6 octahedra and corners with two equivalent PO4 tetrahedra. The corner-sharing octahedral tilt angles are 39°. There are a spread of P–O bond distances ranging from 1.47–1.63 Å. There are six 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 two P5+ atoms. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one Cr4+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Cr4+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a single-bond geometry to one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Cr4+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cr(GeO3)2 by Materials Project

Cr(GeO3)2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Cr4+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with six equivalent GeO4 tetrahedra and edges with two equivalent CrO6 octahedra. There are a spread of Cr–O bond distances ranging from 1.85–2.08 Å. Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with three equivalent CrO6 octahedra and corners with two equivalent GeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 41–60°. There are a spread of Ge–O bond distances ranging from 1.75–1.79 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent Ge4+ atoms. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one Cr4+ and one Ge4+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Cr4+ and one Ge4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cr(GeO3)2 by Materials Project

Cr(GeO3)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Cr4+ is bonded to six O2- atoms to form distorted CrO6 octahedra that share corners with three equivalent GeO4 tetrahedra, corners with two equivalent GeO5 trigonal bipyramids, edges with two equivalent CrO6 octahedra, and an edgeedge with one GeO5 trigonal bipyramid. There are a spread of Cr–O bond distances ranging from 1.82–2.10 Å. There are two inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with three equivalent CrO6 octahedra and corners with two equivalent GeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 35–60°. There are a spread of Ge–O bond distances ranging from 1.75–1.79 Å. In the second Ge4+ site, Ge4+ is bonded to five O2- atoms to form distorted GeO5 trigonal bipyramids that share corners with two equivalent CrO6 octahedra, corners with two equivalent GeO5 trigonal bipyramids, an edgeedge with one CrO6 octahedra, and an edgeedge with one GeO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 36–41°. There are a spread of Ge–O bond distances ranging from 1.76–2.05 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two equivalent Cr4+ and one Ge4+ atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to two equivalent Ge4+ atoms. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to two equivalent Ge4+ atoms. In the fourth O2- site, O2- is bonded in a distorted T-shaped geometry to one Cr4+ and two equivalent Ge4+ atoms. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to one Cr4+ and one Ge4+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Cr4+ and one Ge4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cr(InS2)2 by Materials Project

Cr(InS2)2 is Spinel structured and crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Cr2+ is bonded to four equivalent S2- atoms to form CrS4 tetrahedra that share corners with twelve equivalent InS6 octahedra. The corner-sharing octahedral tilt angles are 56°. All Cr–S bond lengths are 2.39 Å. In3+ is bonded to six equivalent S2- atoms to form InS6 octahedra that share corners with six equivalent CrS4 tetrahedra and edges with six equivalent InS6 octahedra. All In–S bond lengths are 2.66 Å. S2- is bonded in a distorted rectangular see-saw-like geometry to one Cr2+ and three equivalent In3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cr(RhSe2)2 by Materials Project

Cr(RhSe2)2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Cr2+ is bonded to six Se2- atoms to form CrSe6 octahedra that share corners with twelve equivalent RhSe6 octahedra, edges with two equivalent CrSe6 octahedra, and faces with two equivalent RhSe6 octahedra. The corner-sharing octahedra tilt angles range from 50–52°. There are four shorter (2.58 Å) and two longer (2.62 Å) Cr–Se bond lengths. Rh3+ is bonded to six Se2- atoms to form RhSe6 octahedra that share corners with six equivalent CrSe6 octahedra, edges with six equivalent RhSe6 octahedra, and a faceface with one CrSe6 octahedra. The corner-sharing octahedra tilt angles range from 50–52°. There are a spread of Rh–Se bond distances ranging from 2.47–2.62 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to one Cr2+ and three equivalent Rh3+ atoms. In the second Se2- site, Se2- is bonded in a 5-coordinate geometry to two equivalent Cr2+ and three equivalent Rh3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cr(WO4)3 by Materials Project

Cr(WO4)3 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are three inequivalent W6+ sites. In the first W6+ site, W6+ is bonded to six O2- atoms to form corner-sharing WO6 octahedra. The corner-sharing octahedra tilt angles range from 18–29°. There are a spread of W–O bond distances ranging from 1.92–1.95 Å. In the second W6+ site, W6+ is bonded to six O2- atoms to form distorted WO6 octahedra that share corners with two equivalent WO6 octahedra and corners with four equivalent CrO6 octahedra. The corner-sharing octahedra tilt angles range from 22–31°. There are a spread of W–O bond distances ranging from 1.79–2.20 Å. In the third W6+ site, W6+ is bonded to six O2- atoms to form distorted WO6 octahedra that share corners with two equivalent CrO6 octahedra and corners with four equivalent WO6 octahedra. The corner-sharing octahedra tilt angles range from 18–29°. There are a spread of W–O bond distances ranging from 1.78–2.23 Å. Cr6+ is bonded to six O2- atoms to form distorted CrO6 octahedra that share corners with six WO6 octahedra. The corner-sharing octahedra tilt angles range from 23–31°. There are a spread of Cr–O bond distances ranging from 1.65–2.12 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to one W6+ and one Cr6+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two W6+ atoms. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to two W6+ atoms. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to one W6+ and one Cr6+ atom. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to two W6+ atoms. In the sixth O2- site, O2- is bonded in a bent 150 degrees geometry to one W6+ and one Cr6+ atom. In the seventh O2- site, O2- is bonded in a distorted single-bond geometry to one W6+ and one Cr6+ atom. In the eighth O2- site, O2- is bonded in a bent 150 degrees geometry to two W6+ atoms. In the ninth O2- site, O2- is bonded in a bent 150 degrees geometry to one W6+ and one Cr6+ atom. In the tenth O2- site, O2- is bonded in a bent 150 degrees geometry to two W6+ atoms. In the eleventh O2- site, O2- is bonded in a bent 150 degrees geometry to two W6+ atoms. In the twelfth O2- site, O2- is bonded in a distorted single-bond geometry to one W6+ and one Cr6+ atom.

36 MATERIALS SCIENCE↗