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 degreesC. By x-ray diffraction characterization it has been found that the low-index three-dimensional epitaxial orientation relationship BLT(001)parallel toSrRuO(3)(001)parallel toSrTiO(3)(001); BLT[1 (1) over bar0]parallel toSrRuO(3)[100]parallel toSrTiO(3)[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 (2P(r)=31.9 muC/cm(2)) than the (118)-oriented BLT films (2P(r)=20.7 muC/cm(2)), while (001)-oriented BLT films revealed only a small polarization component (2P(r)=1.1 muC/cm(2)), thus demonstrating the ferroelectric anisotropy. (C) 2002 American Institute of Physics.