THERMAL-CONDUCTIVITY ANOMALIES IN (CH3NH3)(5)BI2BR11 FERROELECTRIC-CRYSTALS

We studied thermal conductivity in (CH3NH3)(5)Bi2Br11 crystals (labele d later with MAPBB) between 5 and 330 K during cooling and heating. Th e temperature dependence of thermal conductivity shows hysteresis in f erroelectric phases. Minimum of thermal conductivity in the temperatur e range in with overcritical trace of isomorphous phase transition and the breaking of these dependence at ferroelectric structural phase tr ansition at 312 K it was found. We suppose that anomaly of thermal con ductivity at overcritical region is caused by phonon scattering on flu ctuations of order parameter-spontaneous polarisation.