Structural and optical properties of Pb2KNb5O15 and GdK2Nb5O15 tungsten bronze thin films grown by pulsed laser deposition

Lead potassium niobate Pb2KNb5O15 (PKN) and gadolinium potassium niobate GdK2Nb5O15 (GKN) thin films were grown on (001) MgO single crystal substrates using pulsed laser deposition technique. PKN and GKN thin films were characterized by X-ray diffraction and their linear optical properties were determined. The out-of-plane orientation of PKN thin film depends on the oxygen pressure used during the growth process: [001] for low pressure and [530] for high pressure. In contrast, GKN thin film is oriented [001] and is less sensitive to pressure. PKN and GKN thin films were found transparent and their refractive index quite similar to that reported on TTB-type ferroelectric oxides. GKN film exhibits high bandgap compared to the PKN film. (C) 2017 Elsevier B.V. All rights reserved.