Phase Transitions in CsSnCl 3 and CsPbBr 3 An NMR and NQR Study

The phase transitions in CsSnCl 3 and CsPbBr 3 have been studied by X-ray powder diffraction, by 81 Br-NQR and by 'H-, 119 Sn-, and 113 Cs-NMR. At room temperature in air CsSnCl 3 forms a hydrate which can be dehydrated to the monoclinic phase II of CsSnCl 3 . The high temperature phase I has the Perovskite structure, as the X-ray and NMR experiments show. The three phases of CsPbBr 3 , known from literature, have been corroborated. The results are discussed in the framework of the group ABX 3 , A = alkalimetal ion, B = IV main group ion, and X = Halogen ion