Temperature stability of the dielectric properties of Zr4+-doped CaCu3Ti4.2O12 ceramics for X9R capacitor applications

Abstract

In the present work, a giant dielectric constant (ε′) ∼ 11672 was developed in a CaCu3Ti4.15Zr0.05O12 ceramic with a very low loss tangent (tanδ) ∼ 0.011 at 30 °C and 1 kHz over a temperature range of −60 °C to 110 °C. The resulting dielectric variation (Δε') < ±15% over a temperature range of −60 °C to 210 °C, as well as good nonlinear properties (α ∼ 24.23 and Eb ∼ 8.37 kV cm−1) were achieved in a CaCu3Ti4.15Zr0.05O12 ceramic sintered at 1080 °C for 8 h. According to the EIA standard, this ceramic's excellent dielectric and nonlinear properties provide for potential applications in X9R capacitors and varistors. Very high performance dielectric and nonlinear electrical properties are suggested to have originated from the very high grain boundary resistance (RGB ∼ 515.5 kΩ cm). This was a result of a TiO2-rich environment at the grain boundaries and Zr4+ doping. The grain resistance (RG) and grain boundary resistance (RGB) were studied using impedance spectroscopy. Backscatter FESEM images with elemental mapping and XRD results confirmed the presence of mixed phases of TiO2 and CaCu3Ti4O12.