LAUSR

0.5wt%MnO2-doped (1 − x)BaTiO3–xBiCoO3 ceramics short as (1 − x)BT–xBC–M sintered in air and reducing atmosphere via solid-state process were investigated. The X-ray diffraction results showed that solid solubility in (1 − x)BT–xBC ceramics sintered in the air was higher than that in reducing atmosphere. (1 − x)BT–xBC–M ceramics sintered in air transformed from tetragonal to pseudo-cubic phase when x ≥ 0.1. The scanning electron microscopy results indicated that the average grain size increased with the BC component increasing; however, opposite phenomena occurred in samples sintered in the reducing atmosphere. The dielectric temperature curves of samples sintered in reducing atmosphere were flatted with excellent insulation resistivity of an order of magnitude of 1013 Ω·cm, while anomalous dielectric constant and dielectric loss of samples sintered in the air with deteriorated insulation resistivity of an order of magnitude of 107 Ω·cm. The anti-reduction mechanism of (1 − x)BT–xBC–M system was explained by the “electron–hole” trapping effect and formation of defect dipoles $$\left[ {{\text{Mn}}_{{{\text{Ti}}}} ^{{\prime \prime }} - V_{{\text{O}}}^{{ \cdot \cdot }} } \right]$$ and $$\left[ {2{\text{Co}}_{{{\text{Ti}}}} ^{\prime } - V_{{\text{O}}}^{{ \cdot \cdot }} } \right]$$ .