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

Crystallographic properties such as lattice constants, degree of c-axi s orientation, and cia ratio of tetragonal Pb1-xLaxTiO3 (PLT, x = 0-0. 28) epitaxial thin films grown by pulsed laser deposition on single-cr ystal substrates such as MgO(001) and SrTiO3(001) were evaluated. Gene ral x-ray-diffraction techniques - theta-2 theta scan and phi scan - w ere used to confirm the epitaxial relations between films and substrat es. The epitaxial relations were PLT(001) or (100)//substrate (001) an d PLT[100] or [001]//substrate[100]. Then, using the {303} asymmetric rocking curve technique, more quantitative crystallographic informatio ns 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 calc ulated from the peak location of {303} rocking curve, which is slightl y different from that of the powder or bulk PLT. The existence of a-ax is-oriented domains was also verified in PLT films grown on SrTiO3 sub strate by {303} rocking curve. The origin of the observed ferroelectri c domain structures is discussed based on transformation and thermal s trains involved in the film preparation. (C) 1995 American Institute o f Physics.