Search

Phase field simulations were conducted to investigate the effects of unequally biaxial misfit strains on domain stability diagrams and equilibrium domain structures in an epitaxial ferroelectric PbTiO3 thin layer, which is sandwiched in a nonferroelectric medium. The simulations reveal a multidomain structure in the layer and allow constructing “misfit strain-misfit strain” and “temperature-misfit strain” phase diagrams. It is found that unequally biaxial misfit strains may lead to the presence of a single tetragonal variant, either a-domains or b-domains, which do not exist if the misfit strains are equally biaxial. [ABSTRACT FROM AUTHOR]

This paper demonstrates the combined effects of diffuse phase transition and microstructure on the electrocaloric effect (ECE) in Ba1-xSrxTiO3 (x = 0.2-0.4) ferroelectric ceramics. The ECE was characterized by direct heat flow measurement and an indirect thermodynamic method, which both provided consistent results. With increasing amount of Sr, the phase transition diffused and the grains grew larger. Since larger grains favor a high ΔTmax while a diffuse phase transition does not, the combination of these two effects induced nonmonotonic variation of the ECE. The x = 0.35 sample showed the best performance, with an ECE strength of 0.23 K·m/MV near room temperature. [ABSTRACT FROM AUTHOR]