Studies of gas thermochemical penetrating of rare earth to BaTiO ₃ ceramics and their electric characteristics

The penetrating of rare earth to BaTiO₃ ceramics in gas phase was reported for the first time. The penetrating conditions and effects on electric characteristics of BaTiO₃ ceramics were studied. The results showed that the penetrating of rare earth made the electric characteristics changed obviously. The resistivity of BaTiO₃ ceramics penetrated with rare earth decreased obviously, when the rare earth content was 2% (wt), the penetrating temperature was 860°C and the penetrating time was 4h, the resistivity decreased to the smallest, which changed from 4.3 × 10⁹Ω·m to 4.84Ω·m, and the conductance increased with the increasing of frequency and temperature, the electrical conductivity was better. The constant (ε) of BaTiO ₃ ceramics penetrated with rare earth increased visibly, especially at lower frequency, the constant exhibited PTC effect, and the Curie-temperature (T_c) had gone up to 124.9°C. It was showed through XRD analysis that the penetrated rare earth was entered into the grain boundary. Through X-ray photoelectron spectrum, the binding energy of the elements were analyzed, which indicated that the quantivalence of barium, titanium and rare earth in BaTiO₃ ceramics were variable, and resulted in the improving of the conductibility of BaTiO₃ ceramics. The results of TG-DTA analysis showed that the thermal stability in high temperature of BaTiO₃ ceramics penetrated with rare earth was better.