Effect of Mn on the electrical properties of (Ba, Bi, Nb)-added TiO2 ceramics prepared by the sol-precipitation method

The present work attempted to investigate the addition of Mn on electrical properties of the (Ba, Bi, Nb)-added TiO2 ceramics prepared by the sol-precipitation method. The synthetic methods used to prepare doped TiO2 involve fairly simple solution chemistry, but are characterized by a high degree of control and reproducibility. The content of added manganese is in the range 0-0.02 cat. (cation)%,while that of the other additives is maintained at a constant value. From the experimental results of the present work, it was reasonable to suggest that Mn ions substitute Ti sites and dissolve homogeneously into the lattice of TiO2 rutile phase. In addition, Mn forms interface states at grain boundaries. The results show that an adequate addition of Mn (0.02 cat.%), followed by sintering at 1350 degrees C, leads to an improvement of varistor characteristics, an enhanced alpha of 17 and a breakdown voltage of 3.2 V per grain boundary. The added manganese behaves as an acceptor in the lattice of the rutile phase.