Preparation and properties of spinel-type Zn-Co-Mn oxide negative temperature coefficient ceramic thermistors

Abstract

The effects of the addition of Co ions on the structural and electrical properties of Zn1.10CoxMn1.90-xO4 NTC thermistor composition has been studied. All specimens exhibited a very dense microstructure without any porosities, and the average grain size decreased from 5.21 mu m to 4.86 mu m with an increase in Co content x from 0 to 0.25. All specimens exhibited the sintered density characteristic of at least approximately 96% of the theoretical values and displayed a good NTCR characteristic of less than -4.7%/degrees C. The electrical resistance at room temperature of the Zn1.10Co0.25Mn1.65O4 specimen is 7.2 k Omega. The Zn1.10Co0.15Mn1.75O4 specimen exhibited a minimum activation energy of 0.373 eV.