| Abstrakt: |
Tl2Ta2(PO4)2(HP5O16) is synthesized at 400°C in molten polyphosphoric acids containing Tl, Ta, and P in the ratio 4 : 1 : 15, and its crystal structure is determined: monoclinic cell, a = 5.1469 Å, b = 18.451 Å, c = 10.793 Å, β = 95.65°, Z = 2, sp. gr. P21/m. The framework of the structure is made up of monophosphate and hydrogen pentaphosphate groups which share corners with TaO6 octahedra. The Tl atoms reside in infinite channels. Neighboring pentaphosphate groups are hydrogen-bonded. In the range 60–350°C, the compound has a rather high ionic conductivity, which is tentatively attributed to proton transport. The activation energy of conduction is 48 ± 1 kJ/mol. [ABSTRACT FROM AUTHOR] |
