Specific heat and heat conductivity of BaTiO3 polycrystalline films in the thickness range 20-1100 nm

Thermal properties - specific heat and heat conductivity coefficient - of polycrystalline BaTiO3 films on massive substrates were studied as a function of the temperature and the film thickness by the ac-hot probe method. The anomalies of specific heat with the film thickness decreasing from 1100 to 20 nm revealed the reduction of Tc and excess entropy of the ferroelectric phase transition which becomes diffused. The critical thickness of the film at which Tc = 0 has been estimated as 2.5 nm