Formation of a high stability NTC thick film by low-temperature sintering of Co2.77Mn1.71Fe1.10Zn0.42O8 ceramics containing Bi2O3-B2O3-SiO2-ZnO glass frits

In this paper, a new Pb-free negative temperature coefficient (NTC) thick film thermistor, based on Co2.77Mn1.71Fe1.10Zn0.42O8 (CMFZ), containing Bi2O3-B2O3-SiO2-ZnO (BBSZ) glass frits were successfully fabricated using a spin coating technique. It is confirmed that the resistance of the samples, in the sintering temperature range of 850–1050 °C, generates significant changes due to the change in grain sizes. The room temperature resistance of thick film samples ranges from 118 kΩ to 370 kΩ, while the range of B25/50 values is 4050–4225 K. Aging and analysis indicate that the appropriately increased sintering temperature enhances the stability of thick film samples. Based on the surface morphology, resistance consistency, and aging stability of the samples, the optimal sintering temperature was determined to be 1000 °C with the ΔR/R0 less than 0.35% after aging at 125 °C for 700 h. These findings provide important guidance and significance for the development of the high stability thick film NTC thermistors at a lower sintering temperature.