Growth, structure and dielectric characteristics of Ba[(Fe1/2Nb1/2)0.1Ti0.9]O3 thin films by pulsed laser deposition

Abstract

Ba[(Fe1/2Nb1/2)0.1Ti0.9]O3 thin films were grown on Pt/TiO2/SiO2/Si substrates by pulsed laser deposition at 823 and 923 K. X-ray diffraction analysis suggested the cubic perovskite structure at room temperature. The dielectric properties were investigated at various frequencies (100–106 Hz). Three dielectric abnormalities were observed in the temperature range of 120 to 400 K. The abrupt change in dielectric constant and dielectric loss around 288 K demonstrated the diffused ferroelectric behavior of the thin films. The polarization-electric filed (P-E) loops were measured at different temperatures. Slimmer P-E hysteresis loops were observed with increasing temperature. Raman spectra of Ba[(Fe1/2Nb1/2)0.1Ti0.9]O3 thin films at room temperature indicated local C4v symmetry caused by the displacement of Ti4+ ions. Extra Raman peaks in the thin films compared to that of the bulk ceramic implied extra structure distortion in the thin films. The stress relating to the misfit of the thermal expansion coefficient between the substrate and the thin film might contribute the structure distortion in the thin films.