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本文建立厚度为d的晶粒间界相均匀包围边长为D的三维立方体模型.假定晶粒间界相削弱了晶粒间的交换耦合相互作用.研究了晶粒尺寸及分布对纳米永磁材料有效各向异性及矫顽力的影响.结果表明:单个晶粒的平均各向异性随晶粒尺寸D的增大而增大.且材料的有效各向异性Keff和矫顽力Hc均随平均晶粒尺寸的增大而上升,而上升速率逐渐减慢.Keff和Hc随分布系数的增加而下降,且下降速率逐渐减慢.当Pc=0.7,=1.5,K1(0)=0.2Kh,d=2nm时,我们计算的矫顽力与实验数值符合地很好(Pc是无量纲因子,在0到1之间取值.Kh是晶粒内部正常的磁晶各向异性常数,K1(0)和d分别为晶粒间界相的各向异性常数和厚度).
In this paper, we establish a three-dimensional cube model with a uniform thickness d surrounded by a grain boundary with a thickness of d. It is assumed that the intergranular boundary phase weakens the exchange coupling interaction between the grains. The effects of the grain size and distribution on the nano- The effective anisotropy and the coercive force of the material are studied.The results show that the average anisotropy of a single grain increases with the increase of the grain size D. And the effective anisotropy Keff and the coercive force Hc increased with the increase of the average grain size , and the rate of increase gradually slowed down.Keff and Hc decreased with the increase of the distribution coefficient, and the rate of decrease slowed down gradually.When Pc = 0.7, = 1.5, K1 (0) = 0.2Kh, d = 2nm, we calculated the coercivity in good agreement with the experimental values (Pc is a dimensionless factor, between 0 and 1. Kh is the normal magnetic crystal inside the grain Anisotropy constants, K1 (0) and d are the anisotropy constants and thicknesses of the grain boundary phase, respectively).