Impedance and modulus studies of Na0.9Ba0.1Nb0.9(Sn0.5Ti0.5)0.1O3 ceramic

Abstract

Polycrystalline Na0.9Ba0.1Nb0.9(Sn0.5Ti0.5)0.1O3 is prepared by the solid-state reaction technique. The formation of single-phase material was confirmed by an X-ray diffraction study and it was found to be a tetragonal phase at room temperature. Nyquist plots (Z′′ versus Z′) show that the conductivity behavior is accurately represented by an equivalent circuit model which consists of a parallel combination of bulk resistance and constant phase elements (CPE). The frequency dependence of the conductivity is interpreted in terms of Jonscher’s law. The conductivity σdc follows the Arrhenius relation. The modulus plots can be characterized by the empirical Kohlrausch–Williams–Watts (KWW), φ(t) = exp( − (t/τ)β) function and the value of the stretched exponent (β) is found to be almost independent of temperature. The near value of activation energies obtained from the analyses of modulus and conductivity data confirms that the transport is through an ion hopping mechanism dominated by the motion of the (O2−) ions in the structure of the investigated material.

Keywords

• ceramics
• impedance spectroscopy
• equivalent circuit
• modulus
• electrical conductivity