57Fe Mössbauer spectrometry: A powerful technique to analyze the magnetic and phase characteristics in RE-Fe-B permanent magnets
Lizhong Zhao(赵利忠)1,2,†, Xuefeng Zhang(张雪峰)1,‡, Mi Yan(严密)1, 2, Zhongwu Liu(刘仲武)3, and Jean-Marc Greneche4
1 Institute of Advanced Magnetic Materials, College of Materials & Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018, China; 2 State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Key Laboratory of Novel Materials for Information Technology of Zhejiang Province, Zhejiang University, Hangzhou 310027, China; 3 School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China; 4 Institut des Molécules et Matériaux du Mans CNRS UMR-6283, Le Mans Université, Le Mans F- 72085, France
Abstract This review summarizes the recent advances on the application of 57Fe Mössbauer spectrometry to study the magnetic and phase characteristics of Nd-Fe-B-based permanent magnets. First of all, the hyperfine structures of the Ce2Fe14B, (Ce, Nd)2Fe14B and MM2Fe14B phases are well-defined by using the model based on the Wigner-Seitz analysis of the crystal structure. The results show that the isomer shift δ and the quadrupole splitting ∆ E Q of those 2:14:1 phases show minor changes with the Nd content, while the hyperfine field B hf increases monotonically with increasing Nd content and its value is influenced by the element segregation and phase separation in the 2:14:1 phase. Then, the hyperfine structures of the low fraction secondary phases are determined by the 57Fe Mössbauer spectrometry due to its high sensitivity. On this basis, the content, magnetic behavior, and magnetization of the REFe2 phase, the amorphous grain boundary (GB) phase, and the amorphous worm-like phase, as well as their effects on the magnetic properties, are systematically studied.
Received: 28 May 2020
Revised: 22 October 2020
Accepted manuscript online: 28 October 2020
PACS:
33.45.+x
(M?ssbauer spectra)
Fund: Project supported by the Zhejiang Provincial Natural Science Foundation of China (Grant Nos. LY20E010002, LR18E010001, and LD19E010001), the National Natural Science Foundation of China (Grant Nos. U1704253 and 51801047), Liaoning Revitalization Talents Program (Grant No. XLYC1807177), the Key Research and Development plan of Zhejiang Province, China (Grant No. 2020C05014), and Ten Thousand Talents Plan of Zhejiang Province, China (Grant No. 2018R52003).
Lizhong Zhao(赵利忠), Xuefeng Zhang(张雪峰), Mi Yan(严密), Zhongwu Liu(刘仲武), and Jean-Marc Greneche 57Fe Mössbauer spectrometry: A powerful technique to analyze the magnetic and phase characteristics in RE-Fe-B permanent magnets 2021 Chin. Phys. B 30 013302
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