Phase transitions in ternary caesium lead bromide

Phase transitions in ternary caesium lead bromide (CsPbBr3) were studied by means of DSC, TMA and high temperature X-ray diffraction. The samples were prepared from the solution by water evaporation and from the melt. On the DSC curves as well as on the temperature dependence of the lattice constants of CsPbBr3 only two effects were found belonging to the earlier published phase transitions at 88 and 130degreesC and no further effects. Linear thermal expansion coefficient alpha of individual CsPbBr3 modifications were calculated from both TMA and high temperature X-ray diffraction. The structural parameters of the room temperature orthorhombic phase were refined and the results are presented. CsPbBr3 prepared from the solution contained about 10% of CsPb2Br5 and so the DSC curve of pure CsPb2Br5 was also measured and an effect at a temperature of 68.5degreesC was found.