Interpretation of Mössbauer Spectra of β-FeB and Its Low Temperature Modification, α-FeB

Abstract

Both α and β modifications of FeB are ferromagnetic, and their Curie temperatures and saturation magnetizations are nearly the same, while their Mössbauer spectra are different each other. In order to clarify the origin of these differences, the Mössbauer effect of both α‐ and β‐FeB is measured under an external magnetic field of 4.0 T. The results obtained indicate that both α‐ and β‐FeB reveal anisotropic hyperfine fields. The distribution of the hyperfine field observed in the α‐FeB is discussed on the basis of an anisotropic hyperfine field as well as the proposed crystal structure.

Structure and magnetic properties of the α-FeB phase obtained by mechanical working

“…Thus, the results of the Mossbauer study corrclate with X-ray analysis data in which thc low-temperature modification a-FeB is of CrB(Bf) type crystal structure with one nonequivalent position of Fe atoms rather than a defect structure B27 [2], and it does not consist of a random stacking of structure elements B27 and Bf [3]. The samples prepared in [3] by sintcring may by assumed to have bccn a mixture of cl-and P-FeB.…”

“…On the other hand, Fruchart [2] showed the existence of a low-temperature modification of iron monoboride and proposed a model of a-FeB which is a defect structure of P-FeB. There is an alternative model of a-FeB based on the random stacking of P-FeB (B27) type and CrB(B,) type structures which was proposed for an explanation of magnetic properties and Mossbauer spectra of synthesized Pand r-FeB [3]. Since the presented structure models for r-FeB differ greatly, independent experiments should be made to specify the crystal structure of a-FeB and its magnetic properties.…”

Wet‐Chemical Synthesis of Nanoscale Iron Boride, XAFS Analysis and Crystallisation to α‐FeB

“…[11] Kanaizuka [5] developed an alternative structure model based on the random stacking of CrB and FeB type structures. Barinov et al [8] published the CrB structure type for a-FeB.…”

“…[1,2] Two monoiron boride modifications are known. a-FeB was obtained through solid state reaction routes from the elements [3][4][5][6] or via intermediate phases. [7][8][9][10] When annealed, it transforms to the b-form.…”

“…However, the proposed exchange of B and Fe atoms would lead to M-M distances smaller than in elemental iron and break up the chains of boron atoms. [4] Such alterations would be expected to strongly affect T c , yet the Curie temperatures do not change significantly between aand b-FeB. [4] In addition, this model does not explain the differences in the diffraction patterns of aand b-FeB. [11] Kanaizuka [5] developed an alternative structure model based on the random stacking of CrB and FeB type structures. Barinov et al [8] published the CrB structure type for a-FeB.…”