Coefficients of thermal expansion of the potassium and rubidium halogenide plumbates

The temperature dependence of unit cell parameters for KPb2Br5, RbPb2Cl5 and K0.5Rb0.5Pb2Br5 crystals was studied in the range of 100 to 298 K. Linear and volume thermal expansion coefficients were determined. Analysis revealed the thermal expansion effect on formation of nets of twin boundaries in crystals.