Tuning dielectric and nonohmic properties of CaCu3Ti4O12 ceramics with W doping

• CaWO 4 /TiO 2 -doped CaCu 3 Ti 4 O 12 system obtained via solid-state reaction. • W incorporation affects microstructure and conduction mechanisms. • High dielectric response ( ε≈ 1.2 × 10 4 , tan δ≈ 0.02) on low W content samples. • CaWO 4 /TiO 2 -doped CaCu 3 Ti 4 O 12 on high W content samples enhances nonohmic response. This study investigates the dielectric and nonohmic properties of the CaCu 3 Ti 4 O 12 : 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 CaCu 3 Ti 4 O 12 /CaWO 4 /TiO 2 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 × 10 4 ) with improved tan δ (0.02). Conversely, W250 exhibited higher nonlinear coefficient (α∼38), with low leakage current ( I L ∼14.6 μA/cm 2 ) and breakdown voltage ( Eb ∼198 V. cm −1 ). This solid-state synthesis method provides a way to customize TiO 2 /CaWO 4 -doped CCTO matrices, showcasing promising varistor characteristics that are well-suited for hybrid capacitor-varistor devices and related applications.