Tuning the Curie temperature of Fe 90 Sc 10 nanoglasses by varying the volume fraction and the composition of the interfaces Chaomin Wang a, ⁎, Xiaoke Mu b , Mohammed Reda Chellali b , Askar Kilmametov b , Yulia Ivanisenko b , Herbert Gleiter b,c , Horst Hahn b,c,d a Institute of Applied Physics, Jiangxi Academy of Sciences, 330012 Nanchang, China b Institute of Nanotechnology, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany c Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, 210094 Nanjing, China d KIT-TUD Joint Research Laboratory Nanomaterials, Technische Universität Darmstadt, 64287 Darmstadt, Germany abstract article info Article history: Received 2 September 2018 Accepted 16 September 2018 Available online xxxx Fe 90 Sc 10 nanoglass was produced by consolidating Fe 90 Sc 10 glassy nanoparticles (GNp) into bulk solid material. The average diameters of the GNp, which were produced by inert gas condensation, decreased as He pressure de- creased. The volume fraction of the interfaces within the nanoglass increased as the diameters of the primary GNp decreased. The segregation of the Fe atoms at the surfaces of the GNp varied, so the composition of the in- terfaces was different. As the Curie temperature of Fe 90 Sc 10 nanoglass is primarily dependent on the volume frac- tion and the composition of the interfaces, the Curie temperature increased as He pressure decreased. © 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Keywords: Nanoglass Interfaces Glassy nanoparticles Curie temperature Surface segregation Nanoglasses are a new class of amorphous solid materials that are normally produced by consolidation of glassy nanoparticles (GNp). The knowledge surrounding nanoglasses show that the nanoglasses consist of glassy cores connected by interfaces of reduced density [1,2]. In addition, the composition and the short range order of the inter- faces are different from the cores [3–5]. The interfaces cause the nanoglasses to exhibit several distinctive properties, setting them apart from the corresponding melt-spun rib- bons with identical average compositions [1,2,6–8]. Witte et al. reported that Fe 90 Sc 10 nanoglass is ferromagnetic at room temperature, while Fe 90 Sc 10 melt-spun ribbon is paramagnetic [6]. They claimed that the enhanced ferromagnetism of Fe 90 Sc 10 nanoglass is caused by interfaces with low atomic packing density. Therefore, the initial objective of the present study was to vary the diameters of the primary GNp, which will change the volume fraction of the interfaces, allowing the Curie temperature of the Fe 90 Sc 10 nanoglasses to change. The Fe 90 Sc 10 GNp were produced by inert gas condensation (IGC) as described elsewhere [1]. The IGC chamber was backfilled with high pu- rity He (99.9999%) at various pressures (0.2, 1, and 20 mbar) after evac- uating to 4 × 10 -8 mbar to produce GNp of various average diameters. The Fe\\Sc alloys, with a composition of Fe 85.5 Sc 14.5, were loaded into the temperature-controlled tungsten boats to evaporate the Fe 90 Sc 10 GNp at the similar temperature. Disk-like Fe 90 Sc 10 nanoglass pellets were produced by in situ consolidation of the GNp at 2 GPa and further by ex situ consolidation at 6 GPa. The GNp were collected from the cold finger of the IGC system after the chamber was opened. Tiny GNp were diffused in acetone, ultrasonic vibrated for 2 min, and then the acetone was dropped onto carbon film that was supported by the transmission electron microscopy (TEM) grids. A Tecnai electron microscope was operated in the TEM mode at an accelerating voltage of 200 kV to obtain the GNp TEM images. The amorphous state of the Fe 90 Sc 10 nanoglasses was confirmed by X-ray diffraction (XRD) with a molybdenum source. The average com- position of the Fe 90 Sc 10 nanoglasses was confirmed by electron diffrac- tion X-ray (EDX). Superconducting Quantum Interference Device (SQUID) magnetometry and Mössbauer spectroscopy were applied to characterize the magnetic properties of the samples. The specimens for the Atom Probe Tomography (APT) characterization were cut from the nanoglass pellets via a focused ion beam (FIB). The Local Electrode Atom Probe was operated in the laser pulsing mode to obtain the ele- mental distribution of the nanoglasses. The average diameters of the GNp were counted from the TEM im- ages using Image J software (National Institutes of Health, USA). The GNp that were produced in 20 mbar He (20 mbar GNp) had an average diameter of approximately 12 nm. The average diameter of the 1 mbar GNp was about 8 nm, but the average diameter of the 0.2 mbar GNp was difficult to count due to heavy aggregation of the GNp. According to Granqvist [9], the average diameters of the nanoparticles decrease as inert gas pressure decreases, so the average diameter of the Scripta Materialia 159 (2019) 109–112 ⁎ Corresponding author. E-mail address: wangchaomin@jxas.ac.cn (C. Wang). https://doi.org/10.1016/j.scriptamat.2018.09.025 1359-6462/© 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Contents lists available at ScienceDirect Scripta Materialia journal homepage: www.elsevier.com/locate/scriptamat