High-pressure synthesis, crystal and electronic structures of a new scandium tungstate, Sc{sub 0.67}WO{sub 4}.

Journal Article · Fri Jan 01 04:00:00 EST 2010 · J. Solid State Chem.

DOI:https://doi.org/10.1016/j.jssc.2010.04.039· OSTI ID:979885

Varga, T; Mitchell, J F; Wang, J; Arnold, L; Toby, B H; Malliakas, C D

Negative thermal expansion (NTE) materials possess a low-density, open structure that can respond to high pressure conditions, leading to new compounds and/or different physical properties. Here we report that one such NTE material - white, insulating, orthorhombic Sc{sub 2}W{sub 3}O{sub 12} - transforms into a black compound when treated at 4 GPa and 1400 C. The high pressure phase, Sc{sub 0.67}WO{sub 4}, crystallizes in a defect-rich wolframite-type structure, a dense, monoclinic structure (space group P2/c) containing 1-D chains of edge-sharing WO{sub 6} octahedra. The chemical bonding of Sc{sub 0.67}WO{sub 4} vis-a-vis the ambient pressure Sc{sub 2}W{sub 3}O{sub 12} phase can be understood on the basis of the Sc defect structure. Magnetic susceptibility, resistivity, thermoelectric power and IR spectroscopic measurements suggest that the Sc{sub 0.67}WO{sub 4} sample is a paramagnet whose conductivity is that of a metal in the presence of weak localization and electron-electron interactions. Oxygen vacancies are suggested as a potential mechanism for generating the carriers in this defective wolframite material.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: SC
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 979885
• Report Number(s): ANL/MSD/JA-65991
• Journal Information: J. Solid State Chem., Journal Name: J. Solid State Chem. Journal Issue: 7 ; 2010 Vol. 183; ISSN 0022-4596
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
BONDING
DEFECTS
ELECTRON-ELECTRON INTERACTIONS
ELECTRONIC STRUCTURE
MAGNETIC SUSCEPTIBILITY
OXYGEN
PHYSICAL PROPERTIES
SCANDIUM TUNGSTATES
SYNTHESIS
THERMAL EXPANSION
VACANCIES
WOLFRAMITE