Large Remanent Polarization of Bi4Ti3O12 Films by Ho3+ Substitution

Abstract

Ho-doped bismuth titanate (Bi4-xHoxTi3O12: BHT) and pure Bi4Ti3O12(BIT) thin films with random orientation were fabricated on Pt/Ti/SiO2/Si substrates by rf magnetron sputtering technique. These samples had polycrystalline Bi-layered perovskite structure without preferred orientation, and consisted of well developed rod-like grains with random orientation. For the samples with x=0.25, 1.0, and 1.25, the current-voltage characteristics exhibited negative differential resistance behaviors and their P-V hysteresis loops were characterized by large leakage current, whereas for the samples with x=0.5 and 0.75, the current-voltage characteristics showed simple ohmic behaviors and their P-E hysteresis loops were the saturated and undistorted hysteresis loops. The remanent polarization ( Pr ) and coercive field (Ec) of the BHT Fims with x=0.75 were above 30μC/cm2 and 60KV/cm , respectively.