Dielectric relaxation and conduction mechanism of complex perovskite Ca0.90Sr0.10Cu3Ti3.95Zn0.05O12 ceramic

Abstract In this work, Sr and Zn co-doped calcium copper titanate having nominal formula Ca 0.90 Sr 0.10 Cu 3 Ti 3.95 Zn 0.05 O 12 has been synthesized and systematically studied for structure, dielectric and electrical properties. The phase purity of the prepared composition has been confirmed by X-ray diffraction (XRD) pattern and various structural parameters are presented here with Rietveld refinement data. The Scanning electron microscopy (SEM) image revealed the presence of homogeneous fine-grained microstructure investigated in the prepared ceramic. The impedance data well fitted with 2 R-CPE model confirmed the non-ideality of the system. Dielectric studies have shown the existence of two relaxation processes in low and high frequency domains. Low frequency dielectric response proposed as a combination of Maxwell-Wagner relaxation and intrinsic defect (V o ++ ) while high frequency behavior has been interpreted in terms of polaronic relaxation caused by hopping process of an electron between Ti 3+ and Ti 4+ states. The frequency dependent behavior of conductivity has been well fitted to Dong’s model and interpreted in term of Overlapping Large Polaron Tunneling (OLPT) mechanism. The various parameters; relaxation angular frequency (ω 1 ) of Debye process, ionic hopping frequency (ω 2) , dc conductivity (σ o ), cole- cole parameter (α) and frequency exponent (s) have been determined by Dong’s Model fitting.