Growth of epitaxial films of sodium potassium tantalate and niobate on single-crystal lanthanum aluminate [100] substrates

Epitaxial films of sodium potassium tantalate (Na{sub 0.5}K{sub 0.5}TaO{sub 3}, NKT) and sodium potassium niobate (Na{sub 0.5}K{sub 0.5}NbO{sub 3}, NKN) were grown on single-crystal lanthanum aluminate (LAO) (100) (indexed as a pseudo-cubic unit cell) substrates via an all-alkoxide solution (methoxyethoxide complexes in 2-methoxyethanol) deposition route for the first time. X-ray diffraction studies indicated that the onset of crystallization in powders formed from hydrolyzed gel samples was 550 C. {sup 13}C nuclear magnetic resonance studies of solutions of methoxyethoxide complexes indicated that mixed-metal species were formed, consistent with the low crystallization temperatures observed. Thermal gravimetric analysis with simultaneous mass spectrometry showed the facile loss of the ligand (methoxyethoxide) at temperatures below 400 C. Crystalline films were obtained at temperatures as low as 650 C when annealed in air. {theta}-2{theta} x-ray diffraction patterns revealed that the films possessed c-axis alignment in that only (h00) reflections were observed. Pole-figures about the NKT or NKN (220) reflection indicated a single in-plane, cube-on-cube epitaxy. The quality of the films was estimated via {omega} (out-of-plane) and {psi} (in-plane) scans and full-widths at half-maximum (FWHMs) were found to be reasonably narrow ({approx}1{sup o}), considering the lattice mismatch between the films and the substrate.