Microstructure, Dielectric Properties, Non–Ohmic Behavior, and Humidity-Sensing Characteristics of Ca1+Xcu2.9-Xmg0.1ti4o12 Ceramics

Abstract

This study investigates the properties of Ca1+xCu2.9-xMg0.1Ti4O12 ceramics with x = 0 to 1.5. At x = 0, a CaCu3Ti4O12 (CCTO) phase was observed, while increasing Ca2+ content resulted in the gradual formation of a CaTiO3 (CTO) phase, creating CCTO/CTO composites. Microstructural analysis confirmed the distinct CCTO and CTO phases, with highlighting microstructural changes. The mean grain size of the CCTO phase decreased significantly with CTO formation, attributed to the pinning effect of CTO particles. Loss tangent decreased from 0.146 to 0.025 with increasing x, while dielectric permittivity remained high (>103), driven by Maxwell–Wagner polarization. Impedance spectroscopy revealed grain boundary resistance changes, enhancing internal barrier layer capacitance and reducing the loss tangent. The presence of Cu+ and Cu2+ ions, supporting the formation of semiconducting grains. Improved nonlinear properties were linked to enhanced Schottky barrier heights. Capacitance varied significantly (15% to >100%) with increasing x, demonstrating potential for capacitive humidity sensor.

Keywords: Ceramic composite, Microstructure, Giant dielectric response, Nonlinear electrical characteristics, Humidity sensor