Tuning dielectric and nonohmic properties of CaCu3Ti4O12 ceramics with W doping

Abstract

This study investigates the dielectric and nonohmic properties of the CaCu3Ti4O12: x % W (x = 0.00, 0.02, 0.010, 2.50, 5.00) denoted as CCTO, W002, W010, W250, and W500, respectively. X-ray diffraction analysis confirmed a pseudo-cubic perovskite phase (Im-3 space group) for samples, and a CaCu3Ti4O12/CaWO4/TiO2 composite system for high W content (W250, W500), supported by energy dispersive spectroscopy (EDS) and X-ray fluorescence (XRF) measurements. Positron annihilation lifetime spectroscopy identified V C u ″ / V C a ″ vacancies as the main defects induced by W incorporation, influencing charge carrier mobility at grain boundaries, thus affecting sintering, grain size, and morphology. Lower W content (W002) resulted in a high dielectric response (ε∼1.2 × 104) with improved tanδ (0.02). Conversely, W250 exhibited higher nonlinear coefficient (α∼38), with low leakage current (IL ∼14.6 μA/cm2) and breakdown voltage (Eb∼198 V. cm−1). This solid-state synthesis method provides a way to customize TiO2/CaWO4-doped CCTO matrices, showcasing promising varistor characteristics that are well-suited for hybrid capacitor-varistor devices and related applications.