Synthesis of KTaxNb1−xO3 (KTN) powders and thin films by polymeric precursor method

KTaxNb1−xO3 powders and thin films were synthesized by the polymeric precursor method, derived from the Pechini process. The pure perovskite phase was obtained for powders for various compositions covering the whole solid solution (x from 0 to 1). The optimal synthesis temperature was typically in the range of 550–650 °C depending on the composition. Thin films with the composition x = 0.65 were deposited by spin coating on (11¯02) Al2O3 (R  -plane sapphire) and (11¯02) LaAlO3. On both substrates, the pure perovskite phase was obtained for an annealing temperature as low as 600 °C. The films were epitaxied on LaAlO3 with a high crystalline quality (Δω = 0.5°) and textured on R-plane sapphire. The microstructure of these films was homogeneous and crack-free. In order to increase the film thickness, two multilayered processes were investigated: the “layer after layer crystallization” route led to better density and optical properties (n = 2.10) than the alternative “amorphous route”.

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