Microstructure and enhanced in-plane ferroelectricity of Ba_(0.7)Sr_(0.3)TiO_3 thin films grown on MgAl_2O_4 (001) single-crystal substrate

摘要

The microstructure and in-plane dielectric and ferroelectric properties of highly oriented Ba_(0.7)Sr_(0.3)TiO_3 (BST) thin film grown on MgAl_2O_4 (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 MgAl_2O_4, the film also contained a noticeable amount of misoriented grains and dislocations. The electrical measurements indicated that the film had a shifted Curie temperature (T_C=78℃) and an enhanced in-plane ferroelectricity (remnant polarization P_r=7.1 μC/cm~2) when compared with BST ceramic (T_C≈33℃ and P_r≈0).