Size and pressure effect on the phase transition of BaTiO3 nanoceramics

Grain size effects on the dielectric properties of BaTiO3 (BTO) nanoceramics have been studied by using the modified Ginsburg-Landau-Devonshire (GLD) thermodynamic theory. Considering the existence of internal stresses, it is found that with decreasing grain size the transition temperature of cubic to tetragonal phase decreases. Temperature dependence of the dielectric constant of nano-grain BTO ceramic has been investigated under hydrostatic pressure up to 5 GPa. Adding the hydrostatic pressure and inter-granular stress contributions to a simple GLD type thermodynamic model provides a satisfactory explanation to our experimental results.