The effects of pH value on the characterization of CoMnNiO NTC thermistor nanopowders

The effects of pH value on the properties of CoMnNiO NTC thermistor nanopowders during coprecipitation process are studied. It showed that the particle size and the agglomeration increased with the increase of pH value. At pH 7 and 9, the wave-like grain structure has been observed in the microstructure of sintered samples by SEM, the reason for this phenomenon is that the tetragonal phase separated out of the cubic phase. At pH 8, the powders showed excellent sinterability with homogeneous and dense microstructure in the sintered samples. So the optimal pH value for the preparation of NTC thermistor nanopowders is 8.