A comparative study on Bi4Ti3O12 and Bi3.25La0.75Ti3O12 ferroelectric thin films derived by metal organic decomposition

The crystal orientations and electrical properties of Bi4Ti3O12 (BIT) and Bi3.25La0.75Ti3O12 (BLT) ferroelectric thin films were studied and compared. Stoichiometric BIT and BLT samples were deposited on Pt(111) substrates and crystallized at 750 degrees C to get mixed orientations. The BIT sample exhibited a/b axes orientation with (117) component, while the BLT sample was more c-axis oriented. The 2Pr values of such BIT and BLT were 34.3 mu C/cm(2) and 25.7 mu C/cm(2), respectively. Nevertheless, BLT has much better leakage current and polarization saturation properties. In order to obtain c-axis oriented BIT thin films, excess bismuth was used. BIT with 15% excess bismuth processed at 750 degrees C was purely c-axis oriented and only possessed a 2Pr value of 4.9 mu C/cm(2), while that of 15% excess bismuth BLT sample was 18.3 mu C/cm(2). This can be attributed to the large polarization anisotropy in BIT, and this anisotropy is reduced by lanthanum doping. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3428968]