Influence of Europium Doping on the Electrical Properties of Ba0.9Ca0.1TiO3 Ceramics

Eu-doped Ba0.9Ca0.1TiO3 (BCT10) ceramics with the nominal composition (Ba0.9-xEuxCa0.1)TiO3, where x = 0–0.025, were prepared by the conventional solid-state reaction method. X-ray diffraction analysis and Rietveld refinement revealed a predominantly tetragonal perovskite structure (space group P4mm), with a gradual reduction in tetragonal distortion as the Eu content increased. Scanning electron microscopy showed the grains shrinking steadily with dopant content, from 15.2 µm in the undoped ceramic to about 1.4 µm at the highest doping level. EDS confirmed the presence of the constituent elements and indicated a relatively uniform elemental distribution within the examined region. Impedance spectroscopy revealed thermally activated conduction with two relaxation processes attributed to grains and grain boundaries, described by an equivalent circuit consisting of two Voigt elements incorporating constant phase elements. The activation energies of the first processes decreased with Eu addition, reaching their lowest values at x = 0.01. The subsequent differences in their concentration dependence suggest that Eu doping modifies the electrical transport processes in grains and grain boundaries. These changes, together with the pronounced grain refinement, may be associated with modifications in defect chemistry and grain-boundary contributions to the overall electrical response. Overall, Eu3+ doping provides an effective means of modifying the microstructure and electrical properties of BCT10 ceramics.