Soft ferrite materials for magnetic temperature transducers and applications

Soft ferrites in the CuZnTi system, having the formula Cu 1− x Zn x Ti y Fe 2− y O 4, with 0.50⩽ x⩽0.60 and 0.00⩽ y⩽0.05 were investigated as a function of composition, sintering temperature and cooling speed, in order to obtain materials with controlled T C and very high change rate of permeability with temperature around their T C. The effect of Zn and Ti additions was a drastic change of the Curie temperature with about 10–12 °C for each atomic percent of Zn and Ti introduced into the spinel lattice while the cooling speed changed the behaviour of magnetic permeability with temperature around the Curie point. An application using such magnetic temperature sensors for a thermostat is presented.