Electric Conductivity of $(Bi_{1-x}La_{x}FeO_{3})_{0.5}(PbTiO_{3})_{0.5}$ Ceramics Obtained from Mechanosynthesized Nanopowders

Electric conductivity of $(Bi_{1-x}La_{x}FeO_{3})_{0.5}(PbTiO_{3})_{0.5}$ ceramics obtained from nanopowders synthesized by high-energy milling from respective oxides was studied in the frequency range 10 mHz ÷ 1 GHz. At room temperatures the low-frequency conductivity was found to be dominated by the contribution from poor-conducting grain boundaries, whereas the contribution in the range 1 kHz ÷ 1 MHz, due to the grain interior, was related by us to the small polaron hopping. Moreover, the electron exchange between ferric and ferrous ions activated at higher frequencies was found to be added to the conductivity above ≈ 1 MHz.