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

TL;DR

This study investigates how the specific heat and heat conductivity of polycrystalline BaTiO3 films vary with temperature and thickness, revealing a decrease in critical temperature and phase transition anomalies as films become thinner.

Contribution

It provides new insights into the size-dependent thermal properties and phase transition behavior of BaTiO3 thin films, including the critical thickness where ferroelectricity vanishes.

Findings

Critical temperature decreases with film thinning.

Anomalies in specific heat become diffused at smaller thicknesses.

Critical thickness for ferroelectric phase transition is approximately 2.5 nm.

Abstract

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 ac-hot probe method. The anomalies of specific heat with decreasing of the film thickness from 1100 to 20 nm revealed the reducing of critical temperature (Tc) and excess entropy of the ferroelectric phase transition, which becomes diffused. The critical thickness of the film at which Tc = 0 estimated as 2.5 nm.