Specific heat and thermal conductivity of BaTiO3 polycrystalline thin films

The results of measurements by the ac heater-probe method of the specific heat and thermal conductivity of polycrystalline BaTiO3 films with thickness between 1 and 0.1 mum in a temperature range 120-440 K are presented. In the heating and cooling runs, the phase transition anomalies of the thermal properties in the region of each phase transition in the sequence of symmetry change m3m-4mm-mm2-3m have been observed. A temperature hysteresis is observed, which is the signature of the first order phase transitions. As film thickness decreases, anomalies shift to lower temperatures and became smeared. (C) 2002 American Institute of Physics.