Investigation on relaxation and conduction mechanism in Pb0.75K0.5Nb2O6 new ferroelectric ceramic

• A Pb0.75K0.5Nb2O6 ceramic of single-phase TTB structure was prepared.
• Analyze of electrical properties as function of frequency and temperature.
• Modeling the complex impedance diagrams by the model of equivalent circuit.
• Determination of activation energy.
• Comparison of the obtained results with other TTB compounds.

Using conventional solid state synthesis under air, the sample Pb0.75K0.5Nb2O6 was prepared in a single-phase TTB structure as indicated from X-ray analysis. Impedance spectroscopy analysis of the dielectric properties of Pb0.75K0.5Nb2O6 ceramic were investigated in the frequency range, 1 Hz–1 MHz and in the temperature duration from room temperature to 550 °C.Impedance and modulus plots were used as tools to analyze the sample behavior as a function of frequency. Cole–Cole plots showed non-Debye relaxation. The nature of variation of the electrical conductivity, and value of activation energy of different temperature regions, suggest that the conduction process is of mixed-type (i.e., ionic polaronic and space charge generated from the oxygen ion vacancies). The structural and dielectric results are compared with three others TTB compounds derived from Pb0.75K0.5Nb2O6 (PKN) family: Pb1.85K1.15Li0.15Nb5O15 (PKLN), K3Li2Nb5O15 (KLN) and Pb1.8Gd0.1K1.1Nb5O15 (PGKN).