TF022 - grain size effects of A:B site ratio in BaTiO3 thin films

BaTiO3 films with thickness ~1 micron were deposited on Pt and Cu foil substrates via a CSD process with varying A:B site ratios and were fired at temperatures ranging from 900 to 1200??C. The intent of this study is to determine the impact of A:B site ratio on phase assembly, grain growth, morphology, and film density. Films with excess Barium, up to 5%, fired at and above 1000??C exhibited grain sizes exceeding 5 microns with uniform and isotropic morphology. Films with excess Barium showed no formation of a secondary phase via XRD at 1100??C but a secondary phase was present at 1200??C with barium excess exceeding 4%. For films with large Ba excess and grain sizes in excess of 1 ??m there is no evidence of tetragonality. Electrical testing as a function of voltage and temperature revealed room temperature permittivities of 4000 and tunability greater than 13:1 at 35V applied bias for Ba excess of 3%. Though more thorough research is needed, these results suggest that tuning the Ba:Ti ratio presents possibilities for dielectric property engineering in BaTiO3.