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M Schroffenegger, F. Eder, M. Weil, B. Stöger, K. Schwendtner, U. Kolitsch:
"News about thallium arsenates(V)";
Journal of Alloys and Compounds, 820 (2020), 820; S. 153369.

Systematic phase formation studies in the system Tl/As/O/(H) led to crystal growth of some previously reported and also to numerous novel hydrous and anhydrous phases. Their crystal structures were determined by single crystal X-ray diffraction. This includes the low-temperature forms of TlIH2AsO4 (isotypic with the corresponding phosphate homologues), the hydrogen arsenate TlI2HAsO4 (unique structure), the acidic phases TlIH2AsO4·H3AsO4 and TlI2(H6As4O14)·2H3AsO4 (both unique), the cyclo-tetrametaarsenate TlI4As4O12 (isotypic with its phosphate homologue), TlI8As8O24 (unique with an arsenate anion of novel constitution), the mixed-valent metaarsenate TlITlIIIAs4O12 (unique) and variscite-type TlIIIAsO4·2H2O. TlIH2AsO4, TlI2HAsO4, TlIH2AsO4·H3AsO4, TlI4As4O12 and TlIIIAsO4·2H2O comprise solely of tetrahedral AsO4 units, TlI2(H6As4O14)·2H3AsO4 and TlI8As8O24 comprise of tetrahedral AsO4 and octahedral AsO6 units, and TlITlIIIAs4O12 contains only AsO6 units. The TlI-O bond lengths span a wide range from ∼2.5-3.5 Å associated with coordination numbers between 4 and 12, whereas the TlIII-O bond length are characterized by a narrow range of 2.18-2.32 Å within octahedral coordination spheres.

http://dx.doi.org/10.1016/j.jallcom.2019.153369