Comprehensive and multifaceted conductive mechanisms of Mn doped BaBiO3-based ceramic NTC thermistors.

The Mn³⁺-ions doped Ba(Mn_xBi_1−x)O₃ (x = 0.0, 0.02, 0.04, 0.06, 0.08 and 0.1) ceramic block samples are prepared by traditional solid-state method. The phase structures of these ceramic systems are analyzed, in which the XRD analysis results show the ceramic systems can be formed the solid solutions as the relatively lower Mn-adding content of x ≤ 0.4, and the ceramic blocks appear the additional diffraction peak belonging to the MnO₂ second phase with the increase of x value (≥ 0.6). Combined with the acceptor atom-doping conduction model theory and XPS analysis results, the main conductive forms of these Ba(Mn_xBi_1−x)O₃ thermistors include in the following three kinds: the movable holes formed by the acceptor Mn-doping, the 2Bi⁴⁺ → Bi³⁺ + Bi⁵⁺ disproportionation reaction, and the [Mn³⁺/Mn⁴⁺] small polaron jump. For the electrical properties test results, the NTC thermal properties for the x = 0.02 and x = 0.06 samples are relatively superior: ρ₂₅ − 690 Ω cm, B_25/85 − 3150 K and ρ₂₅ ~ 940 Ω cm, B_25/85 − 3080 K, respectively. [ABSTRACT FROM AUTHOR]