High energy product, temperature compensated permanent magnets for device use at high operating temperatures

Four permanent magnet specimens of the form Sm1-xErx(Co,Fe,Cu,Zr)7.22have been investigated with regard to coercivity, remanence, energy product, and temperature coefficients of remanence and energy product at temperatures ranging from 200K to 800K. The results are compared with previously measured SmCo5and SmCo17type material, with respect to suitability for use at temperatures above 400K. All the specimens measured were superior to the SmCo5and Sm2Co17. The most suitable material of all was found to be Sm0.6Er0.4(Co,Fe,Cu,Zr)7.22with the following properties at 500K: Br= 9.3 kG,IHC= 9.4 kOe, (BH)max=16.5MGOe α= 0.004%/K, β = 0.008%/K.