High-oxygen-pressure crystal growth of ferroelectric Bi4Ti3O12 single crystals

We have investigated the effects of high-oxygen-pressure crystal growth of ferroelectric Bi4Ti3O12 on the polarization properties along the a (b) axis. Domain observations by piezoresponse force microscope demonstrate that a small remanent polarization (P-r) for the crystals grown at 0.02 MPa is attributed to the clamping of 90 degrees domain walls by oxygen vacancies. The vacancy formation of Bi and O during crystal growth at high temperatures is suppressed at a higher oxygen pressure, leading to a larger Pr of 47 mu C/cm(2) for the crystals grown at 1 MPa oxygen. High-oxygen-pressure sintering is proposed to be effective for obtaining Bi4Ti3O12- based devices with enhanced polarization properties. (C) 2007 American Institute of Physics.