Crystal Structure Analysis of Hydrothermally Synthesized Epitaxial (K sub(x)Na sub(1-x))NbO sub(3) Films

Epitaxial (K sub(x)Na sub(1-x))NbO sub(3) films with various compositions x were deposited on Nb-doped (100)SrTiO sub(3) single crystal substrates at 240 [degrees]C by the hydrothermal method. Detailed crystal structures were analyzed by X-ray diffraction. All the (K sub(x)Na sub(1-x))NbO sub(3) films consisted of a perovskite phase without any impurity phase. High-temperature XRD data showed that (K sub(x)Na sub(1-x))NbO sub(3) films with x = 0.03 and 0.86 transformed to a single cubic phase at 600 [degrees]C through the intermediate phase. On the other hand, (K sub(x)Na sub(1-x))NbO sub(3) films with x = 0.24 showed two diffraction peaks at 600 [degrees]C originating from individual phases having different unit cell volumes. The result shows that these films consisted of a mixture of two perovskite phases with K- and Na- rich (K sub(xNa1-x))N bO sub(3) composition.