Influence of copper (Cu²⁺) on the structural, micro-structural, dielectric and non-ohmic properties of Pb_1 − xCu_xTiO₃ materials synthesized using sol–gel method

Ceramic materials of the composition Pb_1 − xCu_xTiO₃ with x = 0.00, 0.04, 0.06 and 0.08 were synthesized using the sol–gel process. An analysis of their structural, dielectric, and non-ohmic characteristics was investigated. X-ray diffraction data and Rietveld refinement indicate the crystallization of the PbTiO₃ ceramic in a pure perovskite structure of tetragonal symmetry, with a phase transition to the pseudo-cubic structure following the incorporation of copper into the PT matrix. The texture, morphology, and microstructure of Pb_1 − xCu_xTiO₃ ceramics were observed using a scanning electron microscope. An impedance spectroscopy study of the dielectric measurements was carried out and revealed that the phase transition temperature decreases proportionally with increasing copper concentration, confirming the incorporation of copper and highlighting its influence on the Curie temperature (T_c), the value of the permittivity (ε_r), and the dielectric losses (tg δ). The electrical characteristics of PCu_xT ceramics reveal that variations in grain size clearly influence the non-ohmic properties. This observation can be attributed to the barrier behavior inherent in the Schottky-type model, as well as to the grain size limitation characteristics of the Internal Barrier Layer Capacitor model.