| Summary: | Lanthanum-modified BaTiO<sub>3</sub> electroceramic materials have superior dielectric and piezoelectric properties. Ba<sub>0.996</sub>La<sub>0.004</sub>Ti<sub>0.999</sub>O<sub>3</sub> (BLT4) seems to be a serious candidate for ultracondensator applications. This manuscript describes the results of hafnium and europium modification of BLT 4 ceramics. The pure and doped ceramic materials were synthesized by the conventional mixed oxide method. The microstructure of obtained samples was examined by scanning electron microscope. The investigations reveal strong correlations between the presence of admixture and the grain size, which was especially visible in the case of the hafnium dopant. The frequency and temperature dielectric characteristics measurements revealed a decrease in electric permittivity. Moreover, the impedance spectroscopy investigations showed severe changes in grains and grain-boundary resistivity, which was connected with changes in electric conductivity.
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