New phase transition in CsPbBr3

Using a combination of in situ high-temperature X-ray diffraction and differential scanning calorimetry methods, the phase behavior of cesium lead bromide CsPbBr3 was investigated in the temperature range of (25-200) degrees C. In addition to the previously reported Pnma -> P4/mbm and P4/mbm -> Pm (3) over barm phase transitions, a new fully reversible transition was found to occur between 45 degrees C and 57 degrees C. A novel phase, which is stable at least in the temperature range of (57-62) degrees C, has an orthorhombic structure with Cmcm space group, which makes the sequence of phase transitions upon heating the same for both CsPbBr3 and CsPbCl3 halides: Pnma -> Cmcm -> P4/mbm -> Pm (3) over barm. (C) 2020 Elsevier B.V. All rights reserved.