Sm2Fe17Nx的结构精修分析

Crystal Parameters of Sm2Fe17Nx Analysis by Rietveled Method

摘要:

通过XRD分析并结合Rietveled结构精修方法研究Sm2Fe17合金的氮化后粉末的物相组成与含量，单胞的精细结构。结果表明：氮原子优先进入9e晶位，氮原子的引入导致了SmFeN晶胞的不对称畸变，致使稀土Sm的6c和3a晶位以及Fe原子的9d晶位占位过饱和，而Fe原子的6c，18f，18h晶位出现了少量缺位情况；在490 ℃，0.3 MPa氮压力下氮化4 h后，氮原子在9e晶位占位率达99.4%，获得主相的含量达97.9%（质量分数，下同），Sm2O3相为0.9%，SmN相为0.5%，α-Fe相为0.7%的高纯高氮含量的SmFeN合金粉末。

Abstract:

The crystal parameters and phase composition of Sm2Fe17Nx powders were investigated by means of XRD (X-ray Diffraction Test) and Rietveled method. The results show that the nitrogen atoms preferentially enter 9e crystal sites, and the introduction of them leads to the asymmetric distortion of SmFeN unit cell, resulting in that the occupancy of 6c and 3a sites for rare-earth Sm and 9d sites for Fe atoms are super-saturation, while the 6c, 18f and 18h sites for Fe atoms are possessed incompletely. After heated at 490 oC for 4 h under 0.3 MPa N2 atmosphere, the occupancy factor of nitrogen atoms in the 9e sites is 99.4% and the high-purity and high-nitrogen-content SmFeN powder with 97.9wt% main phase, 0.9wt% Sm2O3 phase, 0.5wt% SmN phase and 0.7wt% α-Fe phase are obtained.