Tuning dielectric and nonohmic properties of CaCu3Ti4O12 ceramics with W doping

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-Cu ''/V-Ca '' 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 (epsilon similar to 1.2 x 10(4)) with improved tan delta (0.02). Conversely, W250 exhibited higher nonlinear coefficient (alpha similar to 38), with low leakage current (I-L similar to 14.6 mu A/cm(2)) and breakdown voltage (Eb similar to 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.