Phases obtained from the frozen molten systems caesium–tin–halide and caesium–lead–halide

Abstract

Phases and compositions obtained from the molten systems CsPbCl₃–CsPbBr₃ and CsPbCl_nBr_3–n-CsSnCl_nBr_3–n have been identified and compared with those from the CsSnCl₃–CsSnBr₃ system. X-Ray powder data are consistent with all of the products being single-phase solid solutions based on the perovskite lattice and in which there is random distribution of Group IV metal and halide ions. ¹¹⁹Sn Mössbauer data for the phases with cubic unit cells are characterised by high chemical shifts and narrow linewidths, indicative of the presence of tin(II) in octahedral sites, I.r. spectra of the cubic phases contain bands assignable to all of the possible stretching modes but only an average bending mode. There are no bands in the Raman spectra of the cubic phases. Colours obtained in the products are discussed in terms of the population of conductance bands by electrons from ns² orbitals of the Group IV metal ions.