Nd-Fe-C(或BC)三元化合物的晶体结构与磁性

本文中研究了从Nd₁₄Fe₇₈B₈过渡到Nd₁₄Fe₇₈C₈时化合物的晶体结构与内禀磁性。指出轻稀土-Fe-C化合物形成P42/mnm型四方结构的结晶学条件在于适当的热处理温度。在Nd₁₄Fe₇₈B_8-xC_x系列中,随着C含量的增加,居里温度略有减少,饱和磁化强度σ_s出现一个平缓的峰值变化,室温下的剩磁σ_r、内禀矫顽力 _iH_e和磁晶各向异性场H_a都明显增大。含碳样品的各向异性行为与Nd-Fe-B相似,室温下易磁化方向沿e轴,低温下易轴各向异性转变成易锥型。自旋再取向温度随C的增加逐渐降低,但1.5K下的锥角有轻微的增大,这表明在Nd和Fe次晶格的各向异性之间存在着复杂的耦合。此外,适当富Nd的Nd-Fe-C化合物有强的各向异性。 关键词：

ST RUCTURAL AND MAGNETIC PROPERTIES OF TERNARY NEODYMIUM-IRON-CARBON (OR CARBON-BORON) COMPOUNDS

Crystallographic and magnetic properties of the Nd₁₄Fe₇₈B_8-xC_x compounds were investigated. The properly annealing treatment was found to be the condition that the compounds of light rare earth-iron-carbon belonging to the P42/mnm type structure could be formed. The magnetic ordering temperatures of the compounds decreased somewhat with increasing the carbon concentration, but the saturation magnetization σ_s had a gentle maximum, and the residual ma gnetization σ_r, intrinsic coercivity _iH_e as well as the anisotropy field H_a at room temperature showed a significant increase. The anisotropy behaviours of the C-containing samples were similar to Nd-Fe-B. The fact that the transition temperatures of spin reorientation gradually descended with increasing the carbon content while the canting angle at 1.5 K had a slight increase suggested that there was complicate coupling between the anisotropies of Nd and Fe sublattices. In addition, the suitably Nd-rich carbide exhibited relatively large anisotropy.