On the dependence of intrinsic coercivity on grain size in the nucleation-controlled rare earth-iron-boron sintered magnets

The temperature dependence of the intrinsic coercivity of Pr-Fe-B sintered magnets with closely packed and isolated grains of various sizes has been measured. It was found that the reduction factor of the nucleation field in comparison to the ideal value (H_A) is affected by grain size alterations, while the local demagnetization coefficient remains constant. The result is discussed in terms of intra- and intergranular magnetic correlations. A change in the intergranular correlation length is suggested to be one of possible causes of the observed dependence of the reduction factor on the grain size