Deposition of highly oriented (K,Na)NbO3 films on flexible metal substrates

In view of developing flexible, highly textured Pb-free piezoelectric thin films, (K,Na)NbO3 was deposited by chemical solution deposition on cube-textured Ni-W alloy substrates. After heat treatment, a strong (001)pc out-of-plane preferential orientation is created in the (K,Na)NbO3 layer, which also exhibits a sharp in-plane texture with 45°-rotated epitaxial relation to the substrate. The microstructure of the film is strongly dependent on the heat treatment temperature; sub-micrometer grains versus up to 2 μm long particles forming at 600 °C and 900 °C respectively. K4Nb6O17 and (K1−xNax)2Nb4O11 impurity phases were identified depending on the processing temperature.