The analysis of the electrical properties of BLT ceramics fabricated from sol-gel derived powders

Abstract

The (Ba x La1−x )Ti1−x/4O3 (BLT, 0.001 ≤ x ≤ 0.005) amorphous gel was prepared by sol-gel process. The electrical properties of obtained materials has been investigated by impedance spectroscopy. Detailed analysis of impedance spectra allowed to propose an adequate equivalent circuit, which described the electric properties of discussed materials very well. Basing on the obtained circuits and the fitting procedure the grain and grain boundary resistivity was determined as a function of temperature and La concentration. With increase of La admixture the contribution of grain and grains impedance to the bulk impedance changes. It was found that the small amount of La additive decreases the blocking factor of the grain boundary in the temperature range 600–850 K, whereas the amount of La on the level of 0.4–0.5 mol.% causes the sharp increase of the mentioned factor. The fact may be attributed to a decrease of grain activation energy and increase of the grain boundary one.