A short-range ordering in soft magnetic Fe-based metallic glasses studied by Mössbauer spectroscopy and Reverse Monte Carlo method Rafal Babilas a,n , Mariola Kądziolka-Gawel b , Andrzej Burian b,c , László Temleitner d a Institute of Engineering Materials and Biomaterials, Silesian University of Technology, Konarskiego St.18a, 44-100 Gliwice, Poland b August Chelkowski Institute of Physics, University of Silesia, Uniwersytecka 4 St., 40-007 Katowice, Poland c Silesian Center of Education and Interdisciplinary Research, 75 Pulku Piechoty St., 40-500 Chorzów, Poland d Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, P.O. Box 49, H-1525 Budapest, Hungary article info Article history: Received 25 October 2015 Received in revised form 18 November 2015 Accepted 20 December 2015 Available online 23 December 2015 Keywords: Amorphous materials Mössbauer spectroscopy Reverse Monte Carlo modeling Short-range ordering Magnetic properties abstract Selected soft magnetic amorphous alloys Fe 80 B 20 , Fe 70 Nb 10 B 20 and Fe 62 Nb 8 B 30 were produced by the melt-spinning and characterized by X-ray diffraction (XRD), transmission Mössbauer spectroscopy (MS), Reverse Monte Carlo modeling (RMC) and relative magnetic permeability measurements. The Mössbauer spectroscopy allowed to study the local environments of the Fe-centered atoms in the amorphous structure of binary and ternary glassy alloys. The MS provided also information about the changes in the amorphous structure due to the modification of chemical composition by various boron and niobium content. The RMC simulation based on the structure factors determined by synchrotron XRD measure- ments was also used in modeling of the atomic arrangements and short-range order in Fe-based model alloys. Addition of boron and niobium in the ternary model alloys affected the disorder in as-cast state and also influenced on the number of nearest neighbor Fe–Fe atoms, consequently. The distributions of Fe- and B-centered coordination numbers showed that N ¼10, 9 and 8 are dominated around Fe atoms and N ¼9, 8 and 7 had the largest population around B atoms in the examined amorphous alloys. Moreover, the relationship between the content of the alloying elements, the local atomic ordering and the magnetic permeability (magnetic after-effects) was mentioned. & 2015 Elsevier B.V. All rights reserved. 1. Introduction In recent years the variety of metallic glasses based on iron with metalloids have been studied extensively [1–4]. Besides, the ferro- magnetic Fe-based glassy alloys with soft magnetic properties have been mainly examined due to the attractive properties for electric or electronic applications [5]. In order to improve the magnetic prop- erties numerous alloying elements, in different concentration repla- cing Fe, have been considered. The influence of addition of various ferrous and nonferrous atoms on the magnetic properties has been reported [6–8]. Metallic glasses exhibit a lack of the long-range order, which can be observed in conventional crystalline alloys. Their properties are mainly determined by the metastable structure, which can be usually described by local atomic configurations. However interactions between atoms are altered from their crystalline equivalents [9]. Small modifications in composition of glassy alloys can provide fundamental changes of their local atomic structure. At the atomic level, the stability of the molten alloy against crystallization is related to few factors. In some cases, the minor addition of some elements change the atomic packing efficiency or generate strong bonds with other elements [10]. Combination of X-ray diffraction (XRD), Reverse Monte Carlo (RMC) modeling and Mössbauer spectroscopy (MS) gives more structural information of amorphous materials than single XRD method [11]. What is more, the Mössbauer spectroscopy is able to resolve the different kinds of Fe atoms and provide information about the local environment around Fe atoms [12,13]. The Mössbauer spectra of ferromagnetic metallic glasses pre- sent broad lines resulting from the distribution of non-equivalent iron sites and of interatomic distances. The asymmetrical shape, which can occur is due to the correlation amongst isomer shift and magnetic hyperfine field. This state is related with the randomness of the atomic configurations caused by chemical composition and local atomic structure [14]. The aim of the paper is the local structure analysis of soft magnetic Fe-based metallic glasses in as-cast state using the XRD, Mössbauer spectroscopy and Reverse Monte Carlo methods. The combination of Mössbauer spectroscopy and RMC calculation based on high-energy XRD data give an opportunity to describe of the short-range order (SRO) by detect the nearest neighbors of Fe atoms and their inter-atomic distances. Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jmmm Journal of Magnetism and Magnetic Materials http://dx.doi.org/10.1016/j.jmmm.2015.12.068 0304-8853/& 2015 Elsevier B.V. All rights reserved. n Corresponding author. E-mail address: rafal.babilas@polsl.pl (R. Babilas). Journal of Magnetism and Magnetic Materials 406 (2016) 171–178