Atomic structure of Ba0.5Sr0.5TiO3 thin films on LaAlO3

Perovskite barium strontium titanate Ba0.5Sr0.5TiO3(BST) thin films were gr own on (001) LaAlO3 (LAO) using pulsed-laser ablation. The microstructures of the as-grown BST films were studied with selected electron diffraction, transmission electron microscopy, and scanning transmission electron micros copy. The BST thin films are oriented with their [001] directions parallel to the < 102 > directions of the LAO. Both cross-sectional and plan-view st udies show the BST films to be single crystals with smooth surfaces. The in terfaces were seen to be atomically sharp by cross-sectional, high-resoluti on electron microscopy. The density of misfit dislocations was consistent w ith the 4.3% lattice mismatch, and they were found to be dissociated into p artials. (C) 1999 American Institute of Physics. [S0003-6951(99)00443-X].