Title

Structures and Phase Transitions in Pertechnetates

Document Type

Article

Publication Date

7-9-2019

Publication Title

Inorganic Chemistry

Volume

58

Issue

15

First page number:

10119

Last page number:

10128

Abstract

The temperature dependence of the structures of four pertechnetates (ATcO4A = Ag, Tl, Rb, Cs) from 90 K to their melting points is described. Synchrotron X-ray diffraction measurements show that RbTcO4 undergoes a I41/a to I41/amdtransition near 530 K that is associated with a change in the orientation of the TcO4– tetrahedra about the scheelite b axis. AgTcO4 also exhibits a tetragonal scheelite type structure, and this is retained between 90 and 750 K, above which it melted. CsTcO4 has an orthorhombic pseudo-scheelite structure at room temperature and this undergoes a first-order orthorhombic to tetragonal transformation (Pnma to I41/a) near 430 K. TlTcO4 is isostructural with CsTcO4at 90 K, but the orthorhombic to tetragonal transformation proceeds via an intermediate orthorhombic phase. The different behavior found here and described previously for the analogous Re oxide TlReO4 highlights the differences in the chemistry of these two systems.

Disciplines

Inorganic Chemistry

Language

English

UNLV article access

Search your library

Share

COinS