Probing the structural and electrical traits of lead-free Zn/Mn co-substituted CaCu₃Ti₄O₁₂-based perovskite ceramics

Perovskite ceramics are captivating in the field of electronics by virtue of their exceptionally high dielectric permittivity and numerous potential applications such as power transmission, storage devices, and capacitors. Herein, Zn and Mn-co-substituted polycrystalline Ca_1−xZn_xCu_3−yMn_yTi₄O₁₂ (x = 0.05, 0.1, 0.15 and y = 0.1, 0.15, 0.2), a lead-free perovskite ceramics material is fabricated through the economically viable sol–gel technique and employed to examine the structural, morphological, dielectric, and electrical conductivity studies. Co-substitution of Zn and Mn ions leads to a significant reduction in the grain size for the CCTO ceramic compound. All the prepared ceramics exhibit a pristine cubic perovskite phase with a space group of Im-3. The surface topography of the as-prepared thermally etched CCTO ceramic exemplifies homogeneous grain distribution and minimal porosity on the surface. The incorporation of Zn and Mn ions increased the grain boundary resistance (R _GB), lowering the dielectric loss and improving the temperature stability of the dielectric attributes. The relaxation dynamics were highlighted using the complex impedance and modulus framework, whereas the conduction framework was probed using electrical conductivity. The temperature progression of electrical conduction is implemented by Jonscher’s power law and outlined in terms of an overlapping large-polaron tunneling (OLPT) model. The comprehensive impedance and conductivity studies confirmed that the ceramics have a negative temperature coefficient of resistance (NTCR), acknowledging the semiconducting nature of the samples at an elevated temperature. Accordingly, the co-substitution of Zn and Mn ions at the A-sites improves the overall performance of dielectric and electrical features of the CCTO ceramics.