Structural, microstructural, and dielectric properties of a novel La3+ and Mg2+ co-doped CaCu3Ti4O12 ceramics

A novel Ca_1-xLa_xCu_3-yMg_yTi₄O₁₂ (x = y = 0, 0.05, 0.07, 0.09 wt %), ceramic material was synthesized via solid-state reaction, incorporating La³⁺ and Mg²⁺ ions to enhance dielectric permittivity (ε′) and reduce dielectric loss (tanδ). X-ray diffraction confirmed phase purity, while Rietveld refinement provided structural insights with a goodness of fit below 2 %. X-ray Photoelectron Spectroscopy identified Cu⁺ ↔ O ↔ Cu²⁺ and Ti³⁺ ↔ O ↔ Ti⁴⁺ redox pairs facilitating electron hopping. Scanning electron microscopy showed hindered grain growth which minimises tanδ. Notably, the x = 0.05 sample exhibited ε′ = 2.51 × 10⁴ and tanδ = 0.41 at 1 kHz. Nyquist plots revealed a correlation between substantial grain boundary resistance and reducing tanδ. Activation energies for grain (0.058–0.084 eV) and grain-boundary (0.289–0.487 eV) resistance indicated distinct electrical transport mechanisms. The Internal Barrier Layer Capacitance (IBLC) effect led to heterogeneous electrical behaviour. This synergistic co-doping approach achieved desirable dielectric properties, making this material promising for microelectronic applications.