Ba7Nb4−xCexMoO20: structural and electrical property studies of a novel NTC thermal ceramic

Abstract

The hexagonal perovskite oxide Ba₇Nb₄MoO₂₀ is widely studied in chemical devices due to its oxide-ionic conductivity at high temperatures. Ce⁴⁺ doping into Ba₇Nb₄MoO₂₀ was undertaken to optimize small polariton conduction and oxide ionic conductivity simultaneously. Ba₇Nb_4−xCe_xMoO₂₀ materials were synthesized via solid phase sintering. XRD patterns indicate a single phase, SEM scans reveal increased densification with higher Ce doping concentrations, and the resistance temperature range expands from 400–900 °C to 300–1100 °C. Hall tests confirm that Ba₇Nb_4−xCe_xMoO₂₀ carriers are electrons, indicating n-type conductivity. Nyquist plots illustrate that grain boundary resistance governs complex impedance, which shows gradual oxide ionic conductivity enhancement with rising temperature. The aging drift rate decreases to about 1%, suggesting good stability of Ba₇Nb_4−xCe_xMoO₂₀ ceramics. These findings propose a feasible doping strategy for enhancing hexagonal perovskite oxide ceramics.