On the role of mass-transfer processes in ageing of manganite electroceramics

Ageing phenomena in NTC thermistors based on copper–nickel–cobalt manganite electroceramics under thermal exposure at 125 and 170 °C during 1000 h are studied. The observed relative resistance drift is compared with the results of XRD, ceramics microstructure characterization (optical microscopy, SEM), electron probe microanalysis, as well as thermogravimetry measurements. It is shown, at the example of Cu0.1Ni0.8Co0.2Mn1.9O4 electroceramics, that the microstructure origin of ageing phenomena can be adequately explained by thermally stimulated mass-transfer processes in the ceramic body.