Guo Yaozu, Zhao Dong, You Junhua, Pei Wenli, Qu Yingdong, Wang Xiaoyang, Meng Qingyu
School of Materials Science and Engineering, Shenyang University of Technology Shenyang 110870 P. R. China
Key Laboratory for Anisotropy and Texture of Materials, Ministry of Education, Northeastern University Shenyang 110819 P. R. China
RSC Adv. 2018 Nov 19;8(68):38850-38859. doi: 10.1039/c8ra08271e. eCollection 2018 Nov 16.
NdFeB nanoparticles were successfully prepared by using a low-energy chemical method. The microscopic characteristics and formation mechanisms of the phases were investigated at each stage during the preparation of Nd-Fe-B nanoparticles. The Nd-Fe-B intermediates, Nd-Fe-B oxides and reduced Nd-Fe-B nanoparticles were detected and analyzed by using TEM, STEM, XRD, SEM, VSM and Rietveld calculations. The results showed that the intermediate of Nd-Fe-B consisted of FeO and Nd and Fe elements surrounded by nitrile organic compounds. The Nd-Fe-B oxide was composed of NdFeO (48.619 wt%), NdBO (31.480 wt%) and α-Fe (19.901 wt%), which was formed by the reaction among Nd, FeO and BO. NdFeO and NdBO exhibited a perovskite-like lamellar structure, and the grain size was smaller than that of α-Fe. Nd-Fe-B particles were mainly composed of NdFeB and α-Fe phases. The small particles of NdFeO and NdBO and the interstitial position between oxide particles and α-Fe were more favorable for the formation of NdFeB particles. At the same time, the surface of α-Fe particles can also diffuse to form NdFeB nanoparticles. The coercivity of Nd-Fe-B particles was 5.79 kOe and the saturation magnetization was 63.135 emu g.
采用低能化学方法成功制备了钕铁硼纳米颗粒。在钕铁硼纳米颗粒制备的各个阶段，研究了各相的微观特征和形成机制。利用透射电子显微镜（TEM）、扫描透射电子显微镜（STEM）、X射线衍射仪（XRD）、扫描电子显微镜（SEM）、振动样品磁强计（VSM）和Rietveld计算对钕铁硼中间体、钕铁硼氧化物和还原后的钕铁硼纳米颗粒进行了检测和分析。结果表明，钕铁硼中间体由FeO以及被腈类有机化合物包围的Nd和Fe元素组成。钕铁硼氧化物由NdFeO（48.619 wt%）、NdBO（31.480 wt%）和α-Fe（19.901 wt%）组成，它是由Nd、FeO和BO之间的反应形成的。NdFeO和NdBO呈现出钙钛矿状层状结构，且晶粒尺寸小于α-Fe的晶粒尺寸。钕铁硼颗粒主要由NdFeB和α-Fe相组成。NdFeO和NdBO的小颗粒以及氧化物颗粒与α-Fe之间的间隙位置更有利于NdFeB颗粒的形成。同时，α-Fe颗粒表面也能扩散形成钕铁硼纳米颗粒。钕铁硼颗粒的矫顽力为5.79 kOe，饱和磁化强度为63.135 emu/g。
