(1-x)Ni_0.9Mn_2.1O₄-xLaCr_0.6Mn_0.4O₃ composite ceramic with controllable electrical properties for low resistance NTC thermistors

A series of NTC composite ceramics based on (1-x)Ni_0.9Mn_2.1O₄-xLaCr_0.6Mn_0.4O₃ (x = 0.2, 0.25, 0.3, 0.4, and 0.5) were prepared by the solid-state method. The composite ceramics are mainly composed of the orthogonal perovskite phase and the cubic spinel phase. The Ni ions are diffused into the perovskite phase, La and Cr ions are diffused into the spinel phase. The interdiffusion of ions in two phases leads to the structural change of the two phases in the composite ceramics. The conduction mechanism of composite ceramics is the coexistence of electron jumping and double exchange conduction. The resistivity ρ₂₅ and B values vary in the range of 17.4–1056 Ω cm and 2140–3600 K, respectively. Indicating that the electrical properties can be adjusted arbitrarily. In addition, increasing the content of perovskite can improve the stability of the material. The prepared NTC composite ceramic has good electrical properties and stability, so it has good application potential in the field of low resistance.