Significantly enhanced dielectric properties of Y3+ donor-doped CaCu3Ti4O12 ceramics by controlling electrical properties of grains and grain boundaries

Abstract

This paper focuses on the influence of Y3+ donor doping on optimizing dielectric properties of CaCu3Ti4O12 (CCTO) ceramics by controlling electrical properties of grains and grain boundaries (GBs). The Y3+ ions donor-doped Ca1-xYxCu3Ti4O12 (CYCTO, x = 0, 0.01, 0.02, 0.03, 0.05 and 0.07) ceramics were prepared by the conventional solid state reaction method. The influence of doping content on phase structure, morphologies and dielectric properties of CYCTO ceramics was investigated. It was found that Y3+ donor doping scarcely influenced the phase structure of CYCTO, but grain growth in CYCTO ceramics was depressed by Y3+ ions. Interestingly, although the grain size of CCTO was depressed, an enhancing value in dielectric constant (εr) with simultaneously reducing dielectric loss tangent (tanδ) was successfully achieved as Y3+ doping content x increased from 0.01 to 0.03. Impedance spectroscopy analysis further revealed that Y3+ donor doping can improve conductivity of semiconducting grain in CYCTO ceramics with x increasing up to 0.05, which was well consistent with the rising tendency of εr. The resistance of insulating GBs was improved with x increasing up to 0.03, which resulted in a considerable reduction in tanδ. The donor doping type of using Y3+ substitution for A site Ca2+ into CCTO in this work should provide an effective route for further optimizing properties of CCTO ceramics by reducing resistance of grains (Rg) and simultaneously enhancing resistance of GBs (Rgb).