Characterization of electrical properties of Pb-modified BaSnO3 using impedance spectroscopy

The electrical properties of Pb-modifiedBaSnO(3) having general formula Ba1-xPbxO3 (x=0, 0.05,0.10,0.15) were investigated by ac impedance spectroscopy over a wide range of temperature up to 500 degrees C starting from room temperature in the frequency range 100 Hz-1 MHz. X-ray diffraction (XRD) studies have confirmed the formation of a single-phase compound. Scanning electron micrographs show polycrystalline texture of the material. The surface property indicates considerable change with increased number of voids on Pb doping suggesting an increase of porosity in the material. Complex impedance spectrum indicates a decrease in bulk resistance (R-b) with increase in temperature. Bulk resistance of the material has been observed to be concentration dependent. Conductivity analysis indicates that both ac and dc conductivity of the materials increases with increase in temperature. It shows a typical negative temperature coefficient of resistance (NTCR) behaviour like a semiconductor. The conductivity has been found to decrease initially on Pb doping. A maximum conductivity value of similar to 1.01 x 10(-4) Omega m(-1) has been observed for 15 wt.% doping of Pb at 500 degrees C. The electrical modulus analysis provides evidence of single conductivity relaxation of polydispersive nature for both the pure and modified BaSnO3. (c) 2005 Published by Elsevier B.V.