Electrical characterisation of Pb₂Bi₃SmTi₅O₁₈ ceramic using impedance spectroscopy

Abstract

Polycrystalline sample of Pb₂Bi₃SmTi₅O₁₈, a member of tungsten–bronze (TB) family, was prepared using a high temperature solid state reaction technique. X-ray diffraction (XRD) analysis indicated the formation of a single phase orthorhombic structure. AC impedance plots were used as a tool to analyse the electrical behaviour of the sample as a function of frequency at different temperatures. The ac impedance studies revealed the presence of grain boundary effect, from 350°C onward. Complex impedance analysis indicated non-Debye type dielectric relaxation. The Nyquist plot showed the negative temperature coefficient of resistance (NTCR) character of Pb₂Bi₃SmTi₅O₁₈. AC conductivity data were used to evaluate the density of states at Fermi level and activation energy of the compound.

Keywords:

• PB2BI3SMTI5O18
• IMPEDANCE SPECTROSCOPY
• DIELECTRIC RELAXATION
• CONDUCTIVITY