Structural, thermal behaviour and vibrational study of a new mixed cesium-ammonium tellurate

Journal of Chemical Sciences

Ahlem Kabadou1²  Makki Abdelmouleh²  Van Der Lee¹  Wafa Ben Aribia² 

[1] Institut Européen des Membranes (UMR 5635), Université de Montpellier II, cc 047, Place E. Montpellier, France$$;Laboratoire de Sciences des Matériaux et de l’environnement, Faculté des Sciences de Sfax, Université de Sfax, BP 1171, 3000 Sfax, Tunisia$$

关键词: Crystal growth;    X-ray diffraction;    crystal structure;    Raman spectroscopy.;   

DOI  :  

来源: Indian Academy of Sciences

【 摘 要 】

Synthesis, crystal structure, thermal characterization, FTIR and Raman measurements are given for a new mixed compound cesium-ammonium tellurate. X-ray study showed that the [Cs0.92(NH4)0.08]2TeCl4Br2 compound crystallizes in the tetragonal space group P4/mnc, with a = 7.452 (1) Å, c = 10.544 (3) Å and Z = 2. The refinement converged at room temperature to 𝑅𝑝 = 0.093 and 𝑅𝑤𝑝 = 0.076. The structure is considered as isolated octahedral TeCl4Br$^{2−}_{2}$. These anions show a 4° rotation around the fourfold axis against the cubic arrangement of the K2PtCI6 type structure. The monovalent cations (Cs+/NH$^{+}_{4}$) are located between the octahedra ensuring the stability of the structure by ionic and hydrogen bonding contacts: Cs…Cl/Br and N-H$ldotsldots$Cl/Br. A DTA/TGA experiment at high temperature reveals one endothermic peak at 780K for this compound. At low temperature a transition from phase I to phase II was detected at 213K by DSC. This transition, confirmed by Raman analysis, can be attributed to an order-disorder phase transition.

【 授权许可】

Unknown