Influences of Sr2+ Doping on Microstructure, Giant Dielectric Behavior, and Non-Ohmic Properties of CaCu3Ti4O12/CaTiO3 Ceramic Composites.

Jutapol Jumpatam,Narong Chanlek,Bundit Putasaeng,Prasit Thongbai

doi:10.3390/molecules26071994

Abstract

The microstructure, dielectric response, and nonlinear current-voltage properties of Sr2+-doped CaCu3Ti4O12/CaTiO3 (CCTO/CTO) ceramic composites, which were prepared by a solid-state reaction method using a single step from the starting nominal composition of CCTO/CTO/xSrO, were investigated. The CCTO and CTO phases were detected in the X-ray diffraction patterns. The lattice parameter increased with increasing Sr2+ doping concentration. The phase compositions of CCTO and CTO were confirmed by energy-dispersive X-ray spectroscopy with elemental mapping in the sintered ceramics. It can be confirmed that most of the Sr2+ ions substituted into the CTO phase, while some minor portion substituted into the CCTO phase. Furthermore, small segregation of Cu-rich was observed along the grain boundaries. The dielectric permittivity of the CCTO/CTO composite slightly decreased by doping with Sr2+, while the loss tangent was greatly reduced. Furthermore, the dielectric properties in a high-temperature range of the Sr2+-doped CCTO/CTO ceramic composites can be improved. Interestingly, the nonlinear electrical properties of the Sr2+-doped CCTO/CTO ceramic composites were significantly enhanced. The improved dielectric and nonlinear electrical properties of the Sr2+-doped CCTO/CTO ceramic composites were explained by the enhancement of the electrical properties of the internal interfaces.

Highlights

Over the last decades, giant dielectric materials with high dielectric permittivity (ε > 103) have been continuously investigated to develop ceramic capacitors and high energy density storage applications
E.g., CuO or SrTiO3, was observed. This observation is similar to those reported in the literature for the CCTO/CTO composites [20,21,26,28,32], which comprised of ~66.7 mol% CCTO and ~33.3 mol% CTO [18,28,29]
The dielectric and nonlinear electrical properties of CCTO/CTO ceramic composites were successfully improved by doping with Sr2+ ions into the Ca2+ sites of the CCTO and CTO phases

Summary

Introduction

Giant dielectric materials with high dielectric permittivity (ε > 103) have been continuously investigated to develop ceramic capacitors and high energy density storage applications. This is due to a growing demand for miniaturization in microelectronics with the emergence of portable electronic device industry applications (e.g., smartphones and tablets), including applications in the automotive and aerospace industries. Besides the giant dielectric properties, CCTO and related ACu3Ti4O12 ceramics exhibited attractive nonlinear current density-electric field (J-E) properties or non-Ohmic properties [3,4,9,12,13]. CCTO and related ACu3Ti4O12 ceramics can be used in varistor devices when the non-Ohmic parameters can be enhanced

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