Synthesis of FeCo alloy magnetically aligned linear chains by the polyol process: structural and magnetic characterizationElectronic supplementary information (ESI) available: EDS results, SEM of FeCo particles synthesized without external magnetic field, and zfc and fc cooling curves of as-synthesized MALCs. See DOI: 10.1039/c5tc02058a

• Main Authors: Clifford, Dustin M, Castano, Carlos E, Lu, Amos J, Carpenter, Everett E
• Format: Journal Article
• Language: English
• Published: 22.10.2015
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/c5tc02058a

FeCo alloy magnetically aligned linear chains (MALCs) were synthesized by the polyol process using a unique reaction format departing from conventional bench-top reactions. FeCo MALC morphology was obtained in the presence of an external dynamic magnetic field. XRD analysis confirmed the body-centered cubic (bcc) FeCo alloy. Transverse and tangential to the incident X-ray path, XRD analyses of as-synthesized FeCo MALCs were performed further substantiating the linear chain morphology. The average chain diameter was 206 ± 52 nm while Scherrer analysis of (110) gave an average crystallite size of 29 nm. Chemical attachment of each aligned FeCo alloy segment was confirmed by tangential cross-sectioning by a focused ion beam (FIB). Electron diffraction confirmed the bcc FeCo phase with d -spacings of (110), (200) and (211) in good agreement with XRD. The as-synthesized FeCo alloy MALCs possessed a saturation magnetization value, M s , of 205 emu g −1 and a coercivity, H c , of 150 Oe at 300 K. Magnetization was recorded from 300 to 1000 K with increasing temperatures correlating with transitions from hcp Co/α 1 to fcc Co/α 1 at 500 K and to α 1 at 600 K for Co rich portions of the MALCs (Fe 32 Co 68 ). Annealed (1000 K) FeCo MALCs possessed an M s of 212 emu g −1 with a H c value of 120 Oe. Morphological changes of the 1000 K annealed sample were microwire formation and the secondary phase of cubic FeO. As-synthesized FeCo alloy MALCs as highly magnetic, air stable, non-tethered and high aspect ratio structures are candidates for radar absorbent materials (RAMs) when magnetically oriented in coatings or for magnetic sensing devices. FeCo magnetically aligned linear chains (MALCs) were synthesized using polyol based co-precipitation chemistry under an external dynamic magnetic field and are potential candidates for magnetic switching devices and radar absorbing materials (RAMs).