Preparation, characterizations, dielectric properties and nonlinear behavior of (Na+1/3Ca2+1/3Yb3+1/3)Cu3Ti4O12 ceramics

Abstract

We present the investigation of phase formation, microstructural, dielectric properties and nonlinear behaviors of (Na1/3Ca1/3Yb1/3)Cu3Ti4O12 ceramics prepared by a modified sol-gel method under various sintering conditions. According to the Rietveld refinement analysis, the main phase CaCu3Ti4O12-like (Na1/3Ca1/3Yb1/3)Cu3Ti4O12 structure with a lattice constant of ≈7.384 Å was observed in the studied samples. The surface microstructural changes for the ceramics at different conditions were examined by scanning electron microscopy. The dielectric response and nonlinear behaviors of the specimens were methodically explored. At 1 kHz, a high dielectric constant of 5.49 × 103 with a low dielectric loss tangent ≈0.075 was successfully achieved. The sintered (Na1/3Ca1/3Yb1/3)Cu3Ti4O12 ceramics exhibited good nonlinear behavior. The interfacial polarization at the grain boundaries based on the internal barrier layer capacitor structure could explain the dielectric behavior of the studied specimens. From the results of the X-ray photoelectron spectroscopy (XPS) analysis, the presence of Cu+, Cu2+, and Ti3+ ions might be the major cause of the n-type semiconductor nature inside the grains.