Enhanced Piezoelectric Constant of (1-x)BiFeO3?xBiCoO3 Thin Films Grown on LaAlO3 Substrate

Thin films of a rhombohedral-tetragonal solid solution (1-x)BiFeO3–xBiCoO3 with x = 0–0.30 were prepared by chemical solution deposition on LaAlO3(001) and (La0.5,Sr0.5)CoO3(001)/LaAlO3(001) substrates. A BiCoO3-type tetragonal structure with a large c/a of 1.23 was grown adjacent to the substrate whereas a BiFeO3-type rhombohedral one was grown on the tetragonal phase. Co substitution in the rhombohedral phase led to enhancement of piezoelectric constant and d33 reached 100 pm/V, almost double that of BiFeO3.