Structural, thermal behaviour and vibrational study of a new mixed
WAFA BEN ARIBIAa, MAKKI ABDELMOULEHa, VAN DER LEEb
and AHLEM KABADOUa,*
aLaboratoire de Sciences des Matériaux et de l’environnement, Faculté des Sciences de Sfax, Université de
Sfax, BP 1171, 3000 Sfax, Tunisia
bInstitut Européen des Membranes (UMR 5635), Université de Montpellier II, cc 047, Place E. Montpellier,
Abstract. 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 . These anions show a 4◦ rotation around the fourfold axis against
the cubic arrangement of the K2PtCI6 type structure. The monovalent cations are located between
the octahedra ensuring the stability of the structure by ionic and hydrogen bonding contacts: Cs...Cl/Br and
N-H. . . . . . 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.
Graphical Abstract. [Cs0.92(NH4)0.08]2TeCl4Br2 crystallizes in the tetragonal space group (P4/mnc)
at room temperature and belongs to the tetragonal K2PtCl6 type structure.
Keywords. Crystal growth; X-ray diffraction; crystal structure; Raman spectroscopy.