Microstructure and enhanced in-plane ferroelectricity of Ba0.7Sr0.3TiO3 thin films grown on MgAl2O4 (001) single-crystal substrate

The microstructure and in-plane dielectric and ferroelectric properties of highly oriented Ba0.7Sr0.3TiO3 (BST) thin film grown on MgAl2O4 (001) single-crystal substrate through pulsed laser deposition were investigated. X-ray diffraction measurements indicated that BST had a distorted lattice with a tetragonality a∕c=1.012. The cross-sectional observation under transmission electron microscope revealed that, while most of BST grains grew epitaxially on MgAl2O4, the film also contained a noticeable amount of misoriented grains and dislocations. The electrical measurements indicated that the film had a shifted Curie temperature (TC=78°C) and an enhanced in-plane ferroelectricity (remnant polarization Pr=7.1μC∕cm2) when compared with BST ceramic (TC≈33°C and Pr≈0).