Specific heat in ferroelectric BaTiO3 epitaxial thin films

The specific heat (C-p) of thin epitaxial films of BaTiO3 (thickness of 2000 and 60 Angstrom) on SrTiO3 substrates was studied by a.c. calorimetry. A broad anomaly in BaTiO3 films was found, which is quite different from a sharp anomaly observed at 403 K (T-c) in bulk BaTiO3 crystal. The anomalies in C-p were observed at about 443 K for the film with 2000 Angstrom thickness, and at 690 K for the film with 60 Angstrom thickness. No other anomaly in C-p was observed in the low-temperature region down to 80 K. (C) 1999 Elsevier Science Limited. All rights reserved.