Surface structures of binary doped barium strontium titanate films

Cerium (Ce) and yttrium (Y) doped Ba0.6Sr0.4TiO3 (BST) films and not-doped BST ones have been prepared on Pt/Ti/Si02 /Si substrates by Sol-Gel method. The effect of the doping on the surface structures of the as-prepared BST films has been studied. X-ray photoelectron spectrum shows that the surface structures of all BST films are composed of perovskited structure and non-perovskited BST one in terms of the chemical states. Single doping significantly decreases the non-perovskited structure and binary doping decreases more than the former, thus the latter exhibits more improvement in surface structure. Also, scanning electron microscope and atomic force microscope exhibits that the doped films display markedly improved morphologies. Ce doping is beneficial to refine crystal grains, Y doping is helpful to prevent cracks, Ce and Y doping shows better morphologies than the former two. However, X-ray diffraction shows no obvious change in surface structure owing to the effect of the substrate. Additionally, the associated mechanism is discussed.