Influence of Manganese on Lanthanum-Doped BaTiO 3

The minimum room-temperature resistivity for La–Mn–codoped BaTiO 3 occurred at [La +3 ]-5/3[Mn + x ]∼0.35 mol%. Most of the Mn acceptors were in the bulk regions, existing as Mn +2 ions. The others, existing as Mn +3 ions, cause the grain growth inhibition effect and should exist at the grain boundaries, similar to an acceptor level. The slope of the positive temperature coefficient resistance (PTCR) effect (ρ 160° C /ρ 120° C ) was increased with increasing Mn content. However, the maximum order of PTCR (ρ max /ρ min ) existed at [Mn + x ]∼0.06 mol%.