CRYSTALLOGRAPHIC CHARACTERIZATION OF TETRAGONAL (PB,LA)TIO3 EPITAXIAL THIN-FILMS GROWN BY PULSED-LASER DEPOSITION

Crystallographic properties such as lattice constants, degree of c-axis orientation, and cia ratio of tetragonal Pb1-xLaxTiO3 (PLT, x = 0-0.28) epitaxial thin films grown by pulsed laser deposition on single-crystal substrates such as MgO(001) and SrTiO3(001) were evaluated. General x-ray-diffraction techniques - theta-2 theta scan and phi scan - were used to confirm the epitaxial relations between films and substrates. The epitaxial relations were PLT(001) or (100)//substrate (001) and PLT[100] or [001]//substrate[100]. Then, using the {303} asymmetric rocking curve technique, more quantitative crystallographic informations of PLT films could be obtained. The cia ratio and lattice constant along the a axis of c-axis-oriented PLT tetragonal unit cell were calculated from the peak location of {303} rocking curve, which is slightly different from that of the powder or bulk PLT. The existence of a-axis-oriented domains was also verified in PLT films grown on SrTiO3 substrate by {303} rocking curve. The origin of the observed ferroelectric domain structures is discussed based on transformation and thermal strains involved in the film preparation. (C) 1995 American Institute of Physics.