Nb元素掺杂对亚稳相TbCu_(7)型SmFe结构稳定性研究  

Structural Stability of Metastable TbCu_(7)-Type SmFe Phase with Nb Substitution

作　　者：林笑 罗阳 王子龙 于敦波 肖伟 杨伦伟 Lin Xiao;Luo Yang;Wang Zilong;Yu Dunbo;Xiao Wei;Yang Lunwei(Grirem Advanced Materials Co.,Ltd.,Beijing 100088,China;Materials Computation Center,GRIMAT Engineering Institute Co.,Ltd.,Beijing 100088,China)

机构地区：[1]有研稀土新材料股份有限公司,北京100088 [2]有研工程技术研究院有限公司,材料计算中心,北京100088

出　　处：《稀有金属》2024年第1期11-16,共6页Chinese Journal of Rare Metals

基　　金：国家重点研发计划项目(2016YFB0700902)资助。

摘　　要：采用基于密度泛函理论的第一性原理计算方法结合实验数据研究Nb元素掺杂对亚稳相TbCu_(7)型SmFe结构稳定性影响。进行了TbCu_(7)型SmFe超胞的搭建,并由计算结果分析了晶胞参数c/a比值、Nb元素占位、高温下Nb元素占位及Nb含量对TbCu_(7)结构稳定性影响。由计算结果可得,相对于Fe-3g,Fe-6l晶位,Nb元素取代Fe-2e晶位时晶胞具有最低的结合能与形成能,说明Nb进入晶胞结构时优先占据Fe-2e晶位,并且此时结构最稳定;当温度大于870℃时,Nb元素在Fe-2e晶位的占位概率开始下降,Fe-61,Fe-3g晶位的概率开始升高。同时X射线衍射(XRD)图谱表明在850℃左右,TbCu_(7)型SmFe开始向2∶17型SmFe转变,这说明计算结果和实验结果可以很好地吻合起来,由此证明Nb元素占据Fe-2e晶位对结构有很好的稳定作用;随着Nb含量的增加,晶胞发生膨胀,晶胞参数c/a比值开始增大,从另一方面也说明Nb元素的添加可以有效地稳定TbCu_(7)结构。Sm-Fe-N based magnets with theoretical magnetic properties comparable to NdFeB materials are expected to become newtype permanent magnetic materials with great potential.Among the Sm-Fe-N based materials,TbCu_(7)-type SmFe alloy has attracted considerable attention due to its excellent magnetic performance.However,structure of TbCu_(7)-type SmFe compounds is metastable and therefore thermodynamically unstable,which is experimentally stabilized by adding the third element.In recent years,the experimental research of TbCu_(7)-type SmFe material has been very mature,but its theoretical research is not deep enough.In this paper,Nbdoped TbCu_(7)-type SmFe alloy as an example,using the first principle calculation method combined with experimental data to explore the occupation of Nb elements in the crystal structure,and its influence on structural stability and magnetic performance.First-principles calculation was performed by using Vienna Ab-initio Simulation Package (VASP).Generalized gradient approximation (GGA) proposed by Perdew-Burke-Ernzerhof (PBE) was used to describe exchange-correlation effects.Cut-off energy for the plane wave basis was set to 450 eV.The Sm-f electrons were treated as open-core states.For experimental method,raw materials with purity of Sm,Fe and Nb 99.95%(mass fraction) were used to prepare SmFe_(9.5-x)Nb_x(x=0,0.1,0.2,0.3) alloys.Those alloys made by arc-melting were crumbled into fragments,and subsequently melt spun in a molybdenum wheel at the speed of 40 m·s^(-1).Then the obtained ribbons were wrapped in tantalum foil and annealed at the temperature of 600~900℃for 1 h in flowing Ar atmosphere.After that the annealed SmFe-Nb ribbons were pulverized to about 106μm.The obtained magnetic powders were nitrided at 450℃for 24 h in pure nitrogen atmosphere.The entering of Nb element into TbCu_(7)-type SmFe mainly replaced the Fe atomic crystal sites of its crystal structure,where the Fe atomic sites mainly occupied in the site of 2e,3g and 6l.The preferred site of Nb element was obtained

关 键 词：钐铁氮 第一性原理 亚稳相 稳定性 

分 类 号：TM271[一般工业技术—材料科学与工程]