AC magnetic susceptibility measurements have been performed on the Er(Fe1−xCox)3 compounds with x = 0.0, 0.24, 0.44, 0.61 and 1.0. This system shows a competition between the different anisotropies of Fe and Co and the two crystallographically different Er sites. The magnetic phase diagram, previously proposed down to 10 K based on magnetization and neutron diffraction measurements, has been confirmed by magnetic susceptibility experiments. At lower temperatures our results suggest the possible existence of a new spin reorientation (SR) transition at high cobalt content.

The Mossbauer spectra of ErFe3 obtained at 295 and 85 K are analyzed within a model based on previous neutron diffraction measurements. The hyperfine fields and thus the Fe magnetic moments are found parallel to the b axis of the unit cell at 295 K and canted by 57-degrees from the c axis at 85 K. The isomer shifts for the Fe sites are in agreement with the calculated Wigner-Seitz cell volumes.

Neutron diffraction studies of the intermetallic compounds ErFe2.28− Co0.72, ErFe1.68Co1.32, and ErFe1.16Co1.84, above the magnetic ordering temperatures, indicate that iron atoms preferentially occupy the 6c site, while cobalt atoms show a strong preference for the 3b site and a slight preference for the 18h site. The room-temperature pattern for ErFe1.16− Co1.84, below the Curie temperature, indicates a collinear arrangement of the magnetic moments along the c axis. A more complex, non-collinear, array of magnetic moments is indicated for ErFe2.28Co0.72.

On propose un nouveau modele base sur les positions des lanthanides voisins de chaque site du fer. Ce modele peut etre etendu a Y 2 Fe 14 B

The Mössbauer spectra of Y2Fe14B have been measured from 85 to 296 K. Analysis of the spectra indicates that the near-neighbor rare-earth atoms directly influence the orientation of the principal axis of the electric field gradient. The hyperfine parameters are very similar to those of Nd2Fe14B, but the internal fields are somewhat smaller at room temperature in the yttrium compound. The Mösssbauer spectra of Y2(Fe1−xAlx)14B, where x equals 0.00, 0.02, 0.04, 0.06, and 0.08, have been measured at 85 K. The average internal hyperfine field in these compounds decreases linearly with increasing aluminum content.

We have determined the temperature dependence of the internal hyperfine field, isomer shift, and quadrupole shift at each of the six iron sites in Nd2Fe14B. The hyperfine parameters are consistent with the local iron site environments. The quadrupole and isomer shifts and their temperature dependences support our assignments of the relative ordering of the internal hyperfine fields as j2>k2>c≊k1>j1>c. We obtain a Mössbauer temperature of 390 K for Nd2Fe14B, which compares well with the Debye temperature of 420K for pure iron.

The atomic and magnetic structures of Nd2(Fe1−xCox)14B, with x equal to 0.0, 0.1, 0.2, and 0.3, and Y2(Fe1−xCox)14B, with x equal to 0.0, 0.1, 0.2, 0.3, and 0.4, have been investigated by Mössbauer spectroscopy at room temperature and 85 K. A Mössbauer effect spectral component analysis, based on neutron diffraction site populations in Nd2(Fe1−xCox)14B, has revealed a stronger compositional dependence for the hyperfine field and magnetic moment on the j2 site than is observed for the other five iron sites. A similar analysis for the Y2(Fe1−xCox)14B compounds shows lower hyperfine fields and hence moments on the c and e sites, as well as a significant decrease in the hyperfine field at the j1 site as the cobalt concentration is increased. The iron site hyperfine fields, and their dependence on cobalt content, are consistent with the local site coordination environments in both series of compounds.

The crystallographic and magnetic properties of Y2(Fe1−xAlx) 14B, where x equals 0.00, 0.02, 0.04, 0.06, and 0.08, have been investigated by Mössbauer spectroscopy and magnetic measurements at room temperature and 85 K. Magnetic anisotropy and magnetization changes with aluminum substitution indicate that, because of size, the aluminum preferentially occupies the j2 site over the remaining five crystallographically nonequivalent iron sites. This preferential occupation has been confirmed by Mössbauer spectral studies, which indicate that the compositional variation of the hyperfine field for each site is related to the number of near-neighbor aluminum atoms for the site. This compositional variation is helpful in assigning the different spectral components in these alloys as well as in the related Nd2(Fe1−xCox)14B and Y2(Fe1−xCox)14B alloys. In all cases these assignments are consistent with the local symmetry and coordination environment for each site.

Neutron diffraction studies have been made on the intermetallic compounds, ErFe2Ni, ErFe1.5Ni1.5, and ErFeNi2, to determine the effect of the nonmagnetic Ni atoms on the three magnetic phases of ErFe3. Diffraction patterns above the Curie temperature show that Ni atoms almost exclusively occupy the h1 sites. At room temperature, a nearly basal plane ferrimagnetic arrangement of magnetic moments results whereas at 4.2 K, a noncollinear structure is observed, in contrast to the uniaxial collinear structure obtained for ErFe3. The results are explained on the basis of the competitive local anisotropies and the change in exchange interactions of Er-Fe upon substitution of Ni.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and Moessbauer effect study of several novel bridged derivatives of Me2Si[(.eta.5-C5H4)2Fe2(CO)4]2 and the crystal structure of Me2Si[(.eta.5-C5H4)2(CO)Fe(.mu.-CO)2Fe(Ph2PCH2PPh2)]Michael E. Wright, Gary J. Long, Dwayne E. Tharp, and Gregory O. NelsonCite this: Organometallics 1986, 5, 4, 779–784Publication Date (Print):April 1, 1986Publication History Published online1 May 2002Published inissue 1 April 1986https://pubs.acs.org/doi/10.1021/om00135a027https://doi.org/10.1021/om00135a027research-articleACS PublicationsRequest reuse permissionsArticle Views48Altmetric-Citations6LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

The ternary alloys, Y6 (FexMn1−2)23, exhibit interesting magnetic behavior over a range of solid solutions of iron and manganese. The transition metal atoms occupy four crystallographically different sites. For x less than ca. 0.27, the transition metal atoms couple ferromagnetically, whereas for greater values of x they couple antiferromagnetically. By using the iron populations for each site, obtained from neutron diffraction studies, it is possible to determine the Mossbauer effect hyperfine parameter fields for each site. As x increases, the ordering temperature decreases dramatically. At 1.3K in Y6Fe23, the four hyperfine fields range from 372kOe to 250kOe, whereas in Y6(Fe0.52Mn0.48)23 they decrease to values between 100kOe and 10kOe. This decrease apparently results from the increasing frustration of the ferromagnetic iron-iron coupling as additional manganese, which would prefer antiferromagnetic coupling, is introduced into the alloys.

The ternary alloys, Y6 (FexMn1−2)23, exhibit interesting magnetic behavior over a range of solid solutions of iron and manganese. The transition metal atoms occupy four crystallographically different sites. For x less than ca. 0.27, the transition metal atoms couple ferromagnetically, whereas for greater values of x they couple antiferromagnetically. By using the iron populations for each site, obtained from neutron diffraction studies, it is possible to determine the Mössbauer effect hyperfine parameter fields for each site. As x increases, the ordering temperature decreases dramatically. At 1.3K in Y6Fe23, the four hyperfine fields range from 372kOe to 250kOe, whereas in Y6(Fe0.52Mn0.48)23 they decrease to values between 100kOe and 10kOe. This decrease apparently results from the increasing frustration of the ferromagnetic iron-iron coupling as additional manganese, which would prefer antiferromagnetic coupling, is introduced into the alloys.