Phase transitions, structure and ion conductivity of zirconium hydrogen phosphates, H{sub 1{+-}X}Zr{sub 2-X}M{sub X}(PO{sub 4}){sub 3}.H{sub 2}O (M = Nb, Y)
- Kurnakov Institute of General and Inorganic Chemistry of Russian Academy of Sciences, Leninsky pr. 31, Moscow 119991 (Russian Federation)
- Lomonosov Moscow State University, Vorobievy Gory, Moscow 119992 (Russian Federation)
Structure transformations and proton conductivity of hydrogen zirconium phosphates with the NASICON structure, H{sub 1{+-}X}Zr{sub 2-X}M{sub X}(PO{sub 4}){sub 3}.H{sub 2}O (X = 0, 0.02 and 0.1, M = Nb, Y), were studied by X-ray powder diffraction, calorimetry, IR- and impedance spectroscopy. Substitution of zirconium by niobium leads to decrease of the lattice parameters, while yttrium doping leads to their increase. H{sub 0.9}Zr{sub 1.9}Nb{sub 0.1}(PO{sub 4}){sub 3} structure was determined at 493 and 733 K. This phase crystallizes in rhombohedral space group R3-bar c with lattice parameters a = 8.8564(5) A, c = 22.700(1) A at 493 K and a = 8.8470(2) A, c = 22.7141(9) A at 733 K. The a parameter and lattice volume were found to decrease with temperature increasing. Structure transformations upon heating are caused mainly by the decrease of the M1 site and C cavities. Ion conductivity of obtained materials was found to increase in humid atmosphere. Activation energies of conductivity were calculated. Rhombohedral-triclinic phase transition found by X-ray powder diffraction was proved by calorimetry data. According to XRD and IR spectroscopy data hydrogen bond in HZr{sub 2}(PO{sub 4}){sub 3} was found to be weaker than in hydrated material.
- OSTI ID:
- 22029817
- Journal Information:
- Materials Research Bulletin, Vol. 44, Issue 7; Other Information: Copyright (c) 2009 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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