Calculations of the magnetic properties of R2M14B intermetallic compounds (R = rare earth, M = Fe, Co)

The hard magnetic properties of R-M-B (R = rare earth, M = mainly Fe) magnets derive from the specific intrinsic magnetic properties encountered in Fe-rich R2M14B compounds. Exchange interactions are dominated by the 3d elements, Fe and Co, and may be modeled at the macroscopic scale with good accuracy. Based on classical formulae that relate the anisotropy coefficients to the crystalline electric field parameters and exchange interactions, a simple numerical approach is used to derive the temperature dependence of anisotropy in various R2Fe14B compounds (R=Pr, Nd, Dy). Remarkably, a unique set of crystal field parameters give fair agreement with the experimentally measured properties of all compounds. This implies reciprocally that the properties of compounds that incorporate a mixture of different rare-earth elements may be predicted accurately. This is of special interest for material optimization that often involves the partial replacement of Nd with another R element and also the substitution of Co for Fe. (C) 2015 Elsevier By. All rights reserved.