The temperature dependence of the magnetic properties of commercial magnets of greater than 25 MGOe energy product

The hysteresis loops of three commercial magnets with room temperature energy products greater than 25 MGOe were obtained over the temperature range 4.2–700 K in applied magnetic fields extending to ±90 kOe. Two of the samples are of the Sm2Co17 type and the other of Nd2Fe14B. The magnetic parameters extracted from the hysteresis loops are compared with each other and with those of a previously measured 2‐17 specimen. The temperature dependencies of intrinsic coercivities and remanences of the 2‐17’s are similar, as are the magnitudes of the remanences. However, the magnitudes of the intrinsic coercivities differ greatly. For example, at 300 K they are 6.4, 13.4, and 24 kOe, a ratio of approximately 1:2:4. The value for Nd2Fe14B is 11.3 kOe at 300 K. The temperature coefficient of coercivity ranges from -0.225%/K to -0.405%/K for the 2‐17’s and -1.09%/K for Nd2Fe14B. The room temperature energy products are 26 and 27 MGOe for the 2‐17’s and 32 MGOe for Nd2Fe14B. The temperature coefficients of energy product are -0.080%/K and -0.073%/K for the 2‐17’s and -0.398%/K for Nd2Fe14B. The merits of the two classes of material are compared for different applications and operating conditions.