Cold sintering of nickel manganese oxide for thermistor fabrication

Abstract

In this paper we successfully densified NiMn₂O₄ (NMO) ceramics using the cold sintering process (CSP) with various molten salt fluxes as a transient liquid phase, achieving relative densities exceeding 95%. The resulting samples exhibited comparable properties to conventionally sintered counterparts, demonstrating the feasibility of the CSP for NMO thermistor production. Electrical characterization revealed NMO samples sintered via CSP exhibited negative temperature coefficient (NTC) behavior with material constants (B) and temperature coefficients of resistivity (α) akin to conventionally sintered materials in the range of 3500–4300 K and 0.04–0.05 K⁻¹. Despite slightly higher resistances attributed to differences in grain size and impurities, the CSP-produced NMO samples remained within the typical range for NTC thermistors.