Published online by Cambridge University Press: 09 April 2008
Orthorhombic tungsten bronze Pb $_{1-x}$ K $_{2x-3y}$ Smy Nb2O6 (where x = 0.29 and y = 0.145) ceramic has been synthesized by the conventional sintering technique. Preliminary X-ray diffractogram analysis of crystal structure showed that a single phase compound has been formed with orthorhombic system. Frequency and temperature dependences of impedance, modulus, conductivity and dielectric permittivity have been performed in the frequency and temperature range 45 Hz–5 MHz and 35–595 °C respectively. Impedance spectroscopy study showed the presence of both bulk and grain boundary effects in the materials. The complex impedance spectra above 440 °C have been fitted by the superposition of two Cole-Cole types of relaxations. The ac conductivity spectrum obeyed the Jonscher's power law. Modulus analysis indicated the possibility of hopping mechanism for electrical process in the system.