Anisotropic ferroelectric properties of epitaxially twinned Bi3.25La0.75Ti3O12 thin films grown with three different orientations

Epitaxially twinned (001)- , (118)- , and (104)-oriented La-substituted Bi4Ti3O12 (BLT) ferroelectric films have been grown by pulsed laser deposition on (001)- , (011)- , and (111)-oriented SrTiO3 single-crystal substrates, respectively, covered with SrRuO3. Well-defined (001)-oriented BLT films were grown at a substrate temperature as low as 600 °C. By x-ray diffraction characterization it has been found that the low-index three-dimensional epitaxial orientation relationship BLT(001)‖SrRuO3(001)‖SrTiO3(001); BLT[11̄0]‖SrRuO3[100]‖SrTiO3[100] is valid for all epitaxially twinned BLT thin films grown on SrRuO3-covered SrTiO3 substrates in spite of their different orientations. The (104)-oriented BLT films showed an about 1.5 times higher remanent polarization (2Pr=31.9 μC/cm2) than the (118)-oriented BLT films (2Pr=20.7 μC/cm2), while (001)-oriented BLT films revealed only a small polarization component (2Pr=1.1 μC/cm2), thus demonstrating the ferroelectric anisotropy.