Elevated thermal stability of the dielectric properties of CaMoO4–TiO2 composites under temperature variations

Abstract

In this article, the dielectric properties of the ceramic CaMoO₄ (CMO) with additions of 0, 8, 12, and 20% by mass (wt %) of TiO₂ in the radiofrequency (RF) region were studied. X-ray diffraction analysis showed that no secondary phases formed after the addition of TiO₂. Scanning electron microscopy was used to analyse the effects on the morphology of the CMO. Complex Impedance Spectroscopy (CIS) was performed to evaluate the electrical properties of the materials, while temperature coefficient of capacitance (TCC) analysis showed that at 10 kHz, CMO12 (CMO with 12 wt % TiO₂) presented a TCC equal to zero, demonstrating that this material is thermally stable at this frequency. The activation energy (E_a) was calculated by AC conductivity and imaginary part of the electric modulus (M″) at different temperatures. The E_a values were close, indicating that the thermally activated conduction process is the same. Moreover, the addition of TiO₂ resulted in a decrease in the E_a, implying an increased conductivity of the material. The results obtained show that the materials evaluated would be interesting candidates for application in electronic circuits that operate in the radiofrequency region.