On the analytical description of ageing kinetics in ceramic manganite-based NTC thermistors

Experimental results on thermally induced degradation tests carried out at the relatively low ageing temperatures less than 200 °C in NTC ceramic thermistors based on mixed transition-metal manganites (Cu,Ni,Co,Mn)3O4 are discussed. It is first established that, despite of chemical composition and technological features of the investigated ceramics, the stretched-exponential relaxation function of DeBast–Gillard or Williams–Watts is the unique analytical expression describing kinetics of the observed degradation processes.