Frequency and temperature independent (Nb0.5Ga0.5)x(Ti0.9Zr0.1)1-xO2 ceramics with giant dielectric permittivity and low loss

Abstract

Nb5+ and Ga3+ co-doped Ti0.9Zr0.1O2 ceramics were synthesized using the conventional solid-state reaction method. Single rutile-liked phase of octahedron structure were identified for all compositions in (Nb0.5Ga0.5)x(Ti0.9Zr0.1)1-xO2 (NGT) with x = 0.01 to 0.10 by X-ray diffraction patterns coupled with Rietveld refinement. Microstructural scanning image, together with energy dispersive x-ray spectroscopy (EDX), revealed good chemical homogeneity in NGT samples. A giant dielectric permittivity of 5 × 104 and a low loss of 0.02 was obtained in NGT with x = 0.01 due to the contribution of electron-pinned and defect-dipole effect. Furthermore, a temperature (-20–120 °C), frequency (0.1–104 Hz) and bias electric field (100–200 V/mm) independent dielectric permittivity and loss was found in this composition, which is critical for potential applications of supercapacitors.