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Thorium Chemistry in Oxo-Tellurium System under Extreme Conditions

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posted on 2017-02-13, 17:53 authored by Bin Xiao, Philip Kegler, Dirk Bosbach, Evgeny V. Alekseev
Through the use of a high-temperature/high-pressure synthesis method, four thorium oxo-tellurium compounds with different tellurium valence states were isolated. The novel inorganic phases illustrate the intrinsic complexity of the actinide tellurium chemistry under extreme conditions of pressure and temperature. Th2Te3O11 is the first instance of a mixed-valent oxo-tellurium compound, and at the same time, Te exhibits three different coordination environments (TeIVO3, TeIVO4, and TeVIO6) within a single structure. These three types of Te polyhedra are further fused together, resulting in a [Te3O11]8– fragment. Na4Th2­(TeVI3O15) and K2Th­(TeVIO4)3 are the first alkaline thorium tellurates described in the literature. Both compounds are constructed from ThO9 tricapped trigonal prisms and TeVIO6 octahedra. Na4Th2­(TeVI3O15) is a three-dimensional framework based on Th2O15 and Te2O10 dimers, while K2Th­(TeVIO4)3 contains tungsten oxide bronze like Te layers linked by ThO9 polyhedra. The structure of β-Th­(TeIVO3)­(SO4) is built from infinite thorium chains cross-linked by TeIVO32– and SO42– anions. Close structural analysis suggests that β-Th­(TeIVO3)­(SO4) is highly related to the structure of α-Th­(SeO4)2. Additionally, the Raman spectra are recorded and the characteristic peaks are assigned based on a comparison of reported tellurites or tellurates.

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