Syntheses and structures of Ta{sub 2}(WO{sub 2}){sub 0.87}H{sub 0.26}(PO{sub 4}){sub 4} and Ta{sub 2}(MoO{sub 2})(PO{sub 4}){sub 4}
- Department of Chemistry, University of Houston, Houston, TX 77204 (United States)
Tantalum hydrogen phosphate, {beta}-TaH(PO{sub 4}){sub 2}, has a three-dimensional structure that is stable to remarkably high temperature ({approx}600 deg. C) presumably due to the presence of strong hydrogen bonds. Impedance measurements indicate a low conductivity, 2.0 x 10{sup -6} S/cm at 200 deg. C in 5% H{sub 2}. In further studies aimed at enhancing the conductivity by aliovalent doping, we have investigated systematically the synthesis of compounds in the TaH(PO{sub 4}){sub 2}-W{sub 2}P{sub 2}O{sub 11} system at 380 deg. C. As a result, a new phase, Ta{sub 2}(WO{sub 2}){sub 0.87}H{sub 0.26}(PO{sub 4}){sub 4}, was identified and subsequently the molybdenum analog Ta{sub 2}(MoO{sub 2})(PO{sub 4}){sub 4} was also prepared. The structures were determined by single crystal X-ray diffraction techniques. The structures of Ta{sub 2}(WO{sub 2}){sub 0.87}H{sub 0.26}(PO{sub 4}){sub 4} and Ta{sub 2}(MoO{sub 2})(PO{sub 4}){sub 4} can be formally derived from the structure of {beta}-TaH(PO{sub 4}){sub 2} by the replacement of two P-OH protons with an MO{sub 2}{sup 2+} (M = Mo and W) group together with a change in the orientation of some phosphate tetrahedra.
- OSTI ID:
- 21199713
- Journal Information:
- Materials Research Bulletin, Vol. 44, Issue 3; Other Information: DOI: 10.1016/j.materresbull.2008.06.020; PII: S0025-5408(08)00223-7; Copyright (c) 2008 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0025-5408
- Country of Publication:
- United States
- Language:
- English
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