Crystal chemistry peculiarities of Cs 2Te 4O 12

The Raman and IR-absorption spectra of the Cs ₂Te ₄O ₁₂ lattice are first recorded and interpreted. Extraordinary features observed in the structure and Raman spectra of Cs ₂Te ₄O ₁₂ are analyzed by using ab initio and lattice-dynamical model calculations. This compound is specified as a caesium-tellurium tellurate Cs ₂Te ^IV(Te ^VIO ₄) ₃ in which Te ^IV atoms transfer their 5 p electrons to [Te ^VIO ₄] ₃^6- tellurate anions, thus fulfilling (jointly with Cs atoms) the role of cations. The Te ^VI-O-Te ^VI bridge vibration Raman intensity is found abnormally weak, which is reproduced by model treatment including the Cs ⁺ ion polarizability properties in consideration.