Tb_(0.3)Dy_(0.7)(Fe_(1-x)Al_x)_(1.95)合金的结构、磁致伸缩性能和自旋重取向研究

Study on the Structure Magnetostriction and Spin Reorientation of Tb_(0.3)Dy_(0.7)(Fe_(1-x)Al_x)_(1.95) Alloys

本文系统研究了室温下Tb0 3 Dy0 7(Fe1-xAlx) 1 95(x =0 ,0 0 5 ,0 1,0 15 ,0 2 ,0 2 5 ,0 3,0 35 )合金中金属Al替代Fe对晶体结构、磁致伸缩、内禀磁致伸缩、各向异性和自旋重取向的影响。结果发现 ,x <0 4时 ,Tb0 3 Dy0 7(Fe1-xAlx) 1 95完全保持MgCl2 立方Laves相结构 ,晶格常数a随Al含量x的增加而增大。磁致伸缩测量发现 ,随着替代量x的增多磁致伸缩减小 ,x >0 15时超磁致伸缩效应消失 ;x <0 15时磁致伸缩在低场下 (H≤ 4 0kA/m)有小幅增加 ,高场下迅速减小 ,而且易趋于饱和 ,说明添加少量Al有助于减小磁晶各向异性。内禀磁致伸缩λ111随Al替代量x的增加大幅度降低。穆斯堡尔效应表明 ,Tb0 3 Dy0 7(Fe1-xAlx) 1 95合金的易磁化方向随成份和温度在{ 110 }面逐渐偏离了立方晶体的主对称轴 ,即自旋重取向。室温下 ,当x =0 15时 ,Tb0 3 Dy0 7(Fe1-xAlx) 1 95合金中出现了少量非磁性相 ;x >0 15时 ,合金完全呈顺磁性。

The effect of Al substitution for Fe on the structure,magnetostriction,anisotropy and spin reorientation of a series of Tb_ 0.3 Dy_ 0.7 (Fe_ 1-x Al_x)_ 1.95 alloys(x=0,0.05,0.1,0.15,0.20,0.25,0.30,0.35) at room temperature has been investigated.It was found that all compositions of Tb_ 0.3 Dy_ 0.7 (Fe_ 1-x Al_x)_ 1.95 substantially retained the MgCu_2-type C-15 cubic Laves phase structure and the lattice constant increases with increasing x.The substitution of Al increases slightly the magnetostriction in a low magnetic field (H ≤40kA/m) when x<0.15,while the magnetostriction decreases sharply,but is saturated more easily with increasing x in a higher applied field and the magnetostrictive effect disappears at x>0.15.The intrinsic magnetostriction λ_ 111 decreases sharply also with incresasing x.The Mssbauer spectra show that the easy magnetization direction(EMD) of Tb_ 0.3 Dy_ 0.7 (Fe_ 1-x Al_x)_ 1.95 may deviate slightly from the major axis of symmetry <111> with the component and temperature,i.e.spin reocientation are present.A small amount of non-magnetic phase exists for x=0.15 and the alloys become paramagnetism when x>0.15.