Rietveld refinement and impedance spectroscopy of calcium titanate |
| |
Authors: | Monica Sindhu Neetu Ahlawat Sujata Sanghi Ashish Agarwal Reetu Dahiya Navneet Ahlawat |
| |
Affiliation: | 1. Department of Applied Physics, Guru Jambheshwar University of Science and Technology, Hisar-125001, Haryana, India;2. Department of Physics, Choudhary Devi Lal University, Sirsa-125056, Haryana, India |
| |
Abstract: | Single phase perovskite CaTiO3 has been synthesized by conventional solid state reaction technique. The ceramic was characterized by XRD at room temperature and its Rietveld refinement inferred orthorhombic crystal structure with the space group Pbnm. The field dependence of dielectric relaxation and conductivity was measured over a wide frequency range from room temperature to 673 K. Analysis of Nyquist plots of CaTiO3 revealed the contribution of many electrically active regions corresponding to bulk mechanism, distribution of grain boundaries and electrode processes. The dc conductivity depicted a semiconductor to metal type transition. Frequency dependence of dielectric constant (ε′) and tangent loss (tan δ) show a dispersive behavior at low frequencies and is explained on basis of Maxwell-Wagner model and Koop's theory. Both conductivity and electric modulus formalisms have been employed to study the relaxation dynamics of charge carriers. The variation of ac conductivity with frequency at different temperatures obeys the universal Jonscher's power law (σac α ωs). The values of exponent ‘s’ lie in the range 0.13 ≤ s ≤ 0.33, which in light of CBH model suggest a large polaron hopping type of conduction mechanism. |
| |
Keywords: | |
本文献已被 ScienceDirect 等数据库收录! |
|