Impedance spectroscopy analysis of pure and Ni-doped lithium tantalate

Ceramics of LiTaO3 with different Li/Ta ratios and Li0.98−xTa1.004−x/5NixO3 solid solutions with 0⩽x⩽0.20 are studied by impedance spectroscopy in the 1 Hz–1 MHz frequency range and the 500–1200 K temperature range. The evolution of the dielectric properties and the Curie temperature are studied as a function of the Li/Ta ratio and of the Ni content. The ionic conductivity is determined for all compositions from Cole–Cole diagrams and the evolution vs temperature is studied as a function of the Li/Ta ratio and of the Ni content. The results are discussed and related to the substitution mechanism.