Clarification of size effects in polycrystalline BaTiO3 thin films by means of the specific heat measurements: grain size or film thickness?

TL;DR

This study investigates how grain size and film thickness influence the size effects in polycrystalline BaTiO3 thin films by measuring their specific heat and analyzing phase transition properties.

Contribution

It clarifies the roles of grain size and film thickness in size effects, using specific heat measurements to distinguish their impacts in BaTiO3 thin films.

Findings

Relation between thickness and grain size affects size effects

Size effects depend on both grain size and film thickness

Specific heat measurements reveal phase transition variations

Abstract

Specific heat of polycrystalline BaTiO3 thin films on the fused quartz substrate was measured by ac-hot probe method. Phase transition temperature, excess entropy and spontaneous polarization were determined as a function of film thickness and grain size. The variation of the latter was obtained in the limits 30 - 150 nm by changing of the temperature of the substrate during sputtering while thickness of films 20 - 1100 nm was controlled by the conditions of sputtering. It was found that the relation between the thickness and grain size is important for the size effects in polycrystalline films.