Structural and impedance spectroscopy of pseudo-co-ablated (SrBi2Ta2O9)(1-x)-(La0.67Sr0.33MnO3)x composites

Composite thin films of (SrBi2Ta2O9)(1-x)-(La0.67Sr0.33MnO3)x are prepared for the first time using the pulsed-laser deposition technique with ablation occurring from two individual targets. X-ray diffraction and field-emission scanning electron microscopy reveal the formation of ferromagnetic La0.67Sr0.33MnO3 embedded in the ferroelectric SrBi2Ta2O9 phase. Complex impedance spectroscopy is carried out on the composite at different temperatures. Bulk resistance calculated from the complex impedance plot decreases with the increase in temperature up to 80 deg. C, an observation contradicting earlier results. However, the increase in resistivity of the La0.67Sr0.33MnO3 phase with temperature as the metal-to-insulator transition temperature (80 deg. C) is approached explains the observation. Also, the resistivity decreases with the increase in La0.67Sr0.33MnO3 content at a particular temperature. Electric modulus, dielectric spectroscopy and ac conductivity are used to study the transport property of the films. Activation energy, from the Arrhenius plot, is studied to discuss the conduction mechanism in the composite thin films.