Mössbauer spectroscopic analysis of (Nd,Pr,Dy)2(Fe,Co,Ga)14B/α-Fe permanent magnetic nanocomposites
Božidar CEKIĆ, Valentin IVANOVSKI, Mirela Maria CODESCU, Ana UMIĆEVIĆ, Katarina ĆIRIĆ, Eugen MANTAdownload PDF
Abstract. In this paper, it is reported the structural and magnetic properties of Nd13.7Pr0.7Dy0.2Fe73.1Co6.3Ga0.4B5.6 and Nd7.7Pr0.7Dy0.2Fe79.1Co6.3Ga0.4B5.6 magnetic nanocomposites, synthesized by melt-spinning and annealing methods. The Nd-Fe-B ribbons are melt-spun at v=30 m/s in high vacuum and annealed at 715oC for 4 min. in argon. Furthermore, X-ray diffraction and transmission 57Fe Mössbauer spectra at RT are used to investigate the effects of substituent elements: Dy, Pr, Co, Ga on the hard magnetic properties and microstructure of both nanocomposites. Analysis of Mössbauer spectra for Nd13.7Pr0.7Dy0.2Fe73.1Co6.3Ga0.4B5.6 is done in terms of ten Zeeman sextets, one paramagnetic doublet related to Nd1.1Fe4B4 phase and two hyperfine magnetic fields distributions extracted from spectrum. Similar result of analysis of the second nanocomposite is obtained with eleven sextets, one doublet and one distribution. One sextet corresponds to α-Fe phase, while we have identified six iron sextets corresponding to the six distinct iron sites in the Nd2Fe14B structure: 16k1, 16k2, 8j1, 8j2, 4c and 4e. The three remaining sextets belong to Fe3B structure with three inequivalent Fe sites: FeI(8g), FeII(8g) and FeIII(8g). The eleventh sextet of Nd7.7Pr0.7Dy0.2Fe79.1Co6.3Ga0.4B5.6 belongs to FeB. All relevant parameters for both nanocomposites: magnetic hyperfine field, isomer shift and quadrupole splitting are determined for each of these sites. To highlight the thermally induced structural transformations, the quenched samples have been analysed by differential scanning calorimetry and thermo-magnetic measurements. The magnetic properties, measured at RT on the quenched and annealed ribbons, revealed the relationship between the alloy chemical composition and processing.
NdFeB nanocomposites, XRD analysis, Mössbauer spectroscopy, Internal magnetic field, Quadrupole splitting
Published online 11/5/2018, 10 pages
Copyright © 2018 by the author(s)
Published under license by Materials Research Forum LLC., Millersville PA, USA
Citation: Božidar CEKIĆ, Valentin IVANOVSKI, Mirela Maria CODESCU, Ana UMIĆEVIĆ, Katarina ĆIRIĆ, Eugen MANTA, ‘Mössbauer spectroscopic analysis of (Nd,Pr,Dy)2(Fe,Co,Ga)14B/α-Fe permanent magnetic nanocomposites’, Materials Research Proceedings, Vol. 8, pp 70-79, 2018
The article was published as article 8 of the book Powder Metallurgy and Advanced Materials
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