DIRECT MEASUREMENT OF TEMPERATURE-DEPENDENCE OF LATTICE MISMATCHES BETWEEN LPE-GROWN LI(NB,TA)O3 FILM AND LITAO3 SUBSTRATE

Temperature dependence of the lattice mismatch between several compositions of the liquid phase epitaxial (LPE) grown Li(Nb,Ta)O3 films and a LiTaO3 substrate was directly measured between 1000 and 20°C, using a high-temperature X-ray triple- crystal spectrometer. It was found that faceting occurs in the film when the lattice parameters a and c of the film were sufficiently larger than those of the substrate at the growth temperature, and that cracks along the cleavage planes in the film were caused by the thermal expansion mismatch between the film and the substrate. © 1979.