Synthesis, Structure and Properties of Pulsed Laser Deposited BiFeO3-PbTiO3 Thin Films

Bismuth ferrite lead titanate (BFPT) films of composition xBiFeO₃ - (1-x)PbTiO₃, with x from 0 to 1, have been deposited on platinised silicon substrates employing pulsed laser deposition under various temperatures and oxygen pressures. Dense, high quality films were deposited at 530degC with 150 mTorr oxygen pressure. The crystal structure and orientation of the films has been studied by powder x-ray diffraction. The film surface morphology and cross sections were studied on a FEGSEM. The films exhibit significant crystallographic texture across the solid solution range, and appear to exhibit a tetragonal and monoclinic phase mixture across the range. The c/a ratio of the tetragonal phase undergoes a maximum for a composition around x = 0.7 corresponding to the bulk morphotropic phase boundary composition, and is 1.137. However, the presence of the monoclinic phase is not observed in the bulk laser targets.