The effect of the combined substitution of NH4+ and Cl− on the structure of [Cs0.8(NH4)0.2]2TeBr5.6Cl0.4 powder

The structure of [Cs0.8(NH4)0.2]2TeBr5.6Cl0.4 has been determined from conventional X-ray powder diffraction data, by Rietveld method, in Fm−3m cubic space group [a = 10.6798(6) Å, Z = 4] and was further investigated by IR spectroscopy. The refinement of the structure led to final factor χ2 = 0.068. The studied [Cs0.8(NH4)0.2]2TeBr5.6Cl0.4 compound has an antifluorite-type arrangement. The tellurium atoms are surrounded by a disordered of chlorine or bromine atoms octahedron. The Cs or N atoms are located between the octahedral ensuring the stability of the structure by ionic and hydrogen bonding. Two endothermic peaks in thermal behaviour were detected for this compound at 328 K and 461 K, by DSC experiment. An IR spectroscopic study is employed as a means to obtain preliminary structural information and shows the presence of the NH4+ groups.