Enhanced coercivity in Co-doped α-Fe2O3 cubic nanocrystal assemblies prepared via a magnetic field-assisted hydrothermal synthesis

Abstract

Ferromagnetic Co-doped α-Fe2O3 cubic shaped nanocrystal assemblies (NAs) with a high coercivity of 5.5 kOe have been synthesized via a magnetic field (2 kOe) assisted hydrothermal process. The X-ray diffraction pattern and Raman spectra of α-Fe2O3 and Co-doped α-Fe2O3 NAs confirms the formation of single-phase α-Fe2O3 with a rhombohedral crystal structure. Electron microscopy analysis depict that the Co-doped α-Fe2O3 NAs synthesized under the influence of the magnetic field are consist of aggregated nanocrystals (∼30 nm) and of average assembly size 2 μm. In contrast to the NAs synthesized with no magnetic field, the average NAs size and coercivity of the Co-doped α-Fe2O3 NAs prepared with magnetic field is increased by 1 μm and 1.4 kOe, respectively. The enhanced coercivity could be related to the well-known spin–orbit coupling strength of Co2+ cations and the redistribution of the cations. The size increment indicates that the small ferromagnetic nanocrystals assemble into cubic NAs with increased size in the magnetic field that also lead to the enhanced coercivity.

Biological synthesis, physico-chemical characterization of undoped and Co doped α-Fe2O3 nanoparticles using Tribulus terrestris leaf extract and its antidiabetic, antimicrobial applications

“…SEM micrographs of the prepared nanosamples were depicted in figures 3(a) and (b). SEM images clearly evidenced that the bioreduced undoped α-Fe 2 O 3 and Co-Fe 2 O 3 NPs have cubic texture [27], while comparing SEM micrographs, no significant surface morphological difference was found, but Co-Fe 2 O 3 NPs were slightly agglomerated due to its increased magnetic nature.…”

Fe2O3 Review: Nanostructure, Synthesis Methods, and Applications

“…Fasahematite has curie temperatures above 800 ºC and below 1000 ºC (Song & Pistorius, 2019). To produce α-Fe 2O3 nanoparticles is carried out using several methods, including the solgel method, from which the particle size of α-Fe2O3 between 10 -20 nm, the hydrothermal method with a particle size of 30 nm, the ball miling method, with a particle size of 99.14 μm -93.34 μm, and the coprecipitation method, with a particle size of 22.8899 nm (Dewi & Adi, 2018;Fahlepy et al, 2019;Gandha et al, 2017;Malik & Putra, 2018; Various nanostructures have been studied on hematite by varying the synthesis process. The nanostructures formed during the synthesis and fabrication process also depend on different factors such as synthesis methods, types of precursors, stabilizers, substrates, and not to mention their parameters, for example, temperature and time variations in the synthesis process.…”

SINTESIS DAN KARAKTERISASI NANOPARTIKEL Fe2O3 DARI PASIR ALAM DESA LOGAS KABUPATEN KUANTAN SINGINGI

“…Pasir alam mengandung berbagai mineral magnetik seperti α-Fe 2 O 3 , FeTiO 3 , SiO 2 , Magnetite (Fe 3 O 4 ), Maghemite (γ-Fe 2 O 3 ), Alumina (Al 2 O 3 ), dan Rutil (TiO 2 ) [1]. Senyawa α-Fe 2 O 3 merupakan oksida besi paling stabil di bawah kondisi sekitarnya sehingga biasa digunakan dalam katalis, sensor gas, dan bahan elektroda [2]. α-Fe 2 O 3 juga biasa dimanfaatkan sebagai bahan dasar pembuatan magnet permanen [3].…”