Time variation of the electrical conductivity in spinel ferrites

For some spinel ferrites, an investigation was made of the time variation of the electrical conductivity. The phenomenon was observed on quick cooled samples and it is more pronounced immediately after their sintering. It is established that for some ferrites the electrical conductivity decreases with time and for others it increases. At first the variation of the electrical conductivity is pronounced and after certain time, which depends on the measuring temperature, it becomes practically imperceptible. It is shown also that the effect is more pronounced at higher temperatures. By saturation magnetization measurements it is proved that this variation effect of the electrical conductivity is caused by a reordering of the cation distribution after quick cooling of samples.