Rietveld structure refinement, cations distribution and magnetic features of CoFe2O4 nanoparticles synthesized by co-precipitation, hydrothermal, and combustion methods

2016 ◽  
Vol 42 (5) ◽  
pp. 6375-6382 ◽  
Author(s):  
Rohollah Safi ◽  
Ali Ghasemi ◽  
Reza Shoja-Razavi ◽  
Ebrahim Ghasemi ◽  
Tahmineh Sodaee
2018 ◽  
Vol 42 (4) ◽  
pp. 3050-3062 ◽  
Author(s):  
S. Fatemeh Shams ◽  
Mehrdad Kashefi ◽  
Carolin Schmitz-Antoniak

The effects of synthesis parameters on the structural and magnetic features of CoFe2O4 nanoparticles have been investigated and their mutual correlations optimized by using response surface methodology.


Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 341
Author(s):  
Tien Hiep Nguyen ◽  
Gopalu Karunakaran ◽  
Yu.V. Konyukhov ◽  
Nguyen Van Minh ◽  
D.Yu. Karpenkov ◽  
...  

This paper presents the synthesis of Fe–Co–Ni nanocomposites by chemical precipitation, followed by a reduction process. It was found that the influence of the chemical composition and reduction temperature greatly alters the phase formation, its structures, particle size distribution, and magnetic properties of Fe–Co–Ni nanocomposites. The initial hydroxides of Fe–Co–Ni combinations were prepared by the co-precipitation method from nitrate precursors and precipitated using alkali. The reduction process was carried out by hydrogen in the temperature range of 300–500 °C under isothermal conditions. The nanocomposites had metallic and intermetallic phases with different lattice parameter values due to the increase in Fe content. In this paper, we showed that the values of the magnetic parameters of nanocomposites can be controlled in the ranges of MS = 7.6–192.5 Am2/kg, Mr = 0.4–39.7 Am2/kg, Mr/Ms = 0.02–0.32, and HcM = 4.72–60.68 kA/m by regulating the composition and reduction temperature of the Fe–Co–Ni composites. Due to the reduction process, drastic variations in the magnetic features result from the intermetallic and metallic face formation. The variation in magnetic characteristics is guided by the reduction degree, particle size growth, and crystallinity enhancement. Moreover, the reduction of the surface spins fraction of the nanocomposites under their growth induced an increase in the saturation magnetization. This is the first report where the influence of Fe content on the Fe–Co–Ni ternary system phase content and magnetic properties was evaluated. The Fe–Co–Ni ternary nanocomposites obtained by co-precipitation, followed by the hydrogen reduction led to the formation of better magnetic materials for various magnetically coupled device applications.


2020 ◽  
Vol 62 (2) ◽  
pp. 235
Author(s):  
Д.А. Балаев ◽  
С.В. Семенов ◽  
А.А. Дубровский ◽  
А.А. Красиков ◽  
С.И. Попков ◽  
...  

Fe3O4 / CoFe2O4 nanoparticles with a core-shell structure with an average size of 5 nm were obtained by co-precipitation from solutions of iron and cobalt chlorides. An analysis of the magnetic properties of the resulting system and their comparison with the data for single-phase Fe3O4 (4 nm) and CoFe2O4 (6 nm) nanoparticles led to the conclusion that there is a noticeable interaction between the soft magnetic (Fe3O4) and magnetically hard (CoFe2O4) phases that form the core and the shell of hybrid particles, correspondingly.


2020 ◽  
Vol 39 (03) ◽  
Author(s):  
NGHIA T. BUI ◽  
LOAN T. B. DUONG ◽  
LAN HUONG NGUYEN ◽  
NGOC T. T. TRAN

In this work, magnetic nanocomposites were produced by incorporating cobalt superparamagnetic (CoFe2O4) nanoparticles into the biopolymer matrix which was extracted from grapefruit peel. In which, the magnetic nanoparticles were prepared by co-precipitation approach and the nanocomposite formation was carried out with the support of ultrasonic waves. The obtained biopolymer, nanoparticles and nanocomposites were characterized by Fourier transform infrared (FT-IR) while nanoparticles and nanocomposites were further characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). Finally, the capability to collect the Tetraselmis sp. microalgae using the achieved superparamagnetic nanocomposites was assessed and effects of various factors including material weight, stirring speed and stirring time on the recovery yield were also investigated. It was found that a recovery yield of higher than 90% was attained when using the nanocomposites at the concentration of 4 g/L. In addtition, the highest efficiency was reached in the case the coagulation was done by stirring at 200 rpm for 3 mins and the flocculation was performed by slow stirring at 50 rpm for 2 mins


Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3684
Author(s):  
Kacuk Cikal Nugroho ◽  
Ubaidillah Ubaidillah ◽  
Retna Arilasita ◽  
Margono Margono ◽  
Bambang Hari Priyambodo ◽  
...  

This study investigated the effect of adding strontium (Sr)-doped cobalt ferrite (CoFe2O4) nanoparticles in carbonyl iron particle (CIP)-based magnetorheological fluids (MRFs). Sr-CoFe2O4 nanoparticles were fabricated at different particle sizes using co-precipitation at calcination temperatures of 300 and 400 °C. Field emission scanning electron microscopy (FESEM) was used to evaluate the morphology of the Sr-CoFe2O4 nanoparticles, which were found to be spherical. The average grain sizes were 71–91 nm and 118–157 nm for nanoparticles that had been calcinated at 300 and 400 °C, respectively. As such, higher calcination temperatures were found to produce larger-sized Sr-CoFe2O4 nanoparticles. To investigate the rheological effects that Sr-CoFe2O4 nanoparticles have on CIP-based MRF, three MRF samples were prepared: (1) CIP-based MRF without nanoparticle additives (CIP-based MRF), (2) CIP-based MRF with Sr-CoFe2O4 nanoparticles calcinated at 300 °C (MRF CIP+Sr-CoFe2O4-T300), and (3) CIP-based MRF with Sr-CoFe2O4 nanoparticles calcinated at 400 °C (MRF CIP+Sr-CoFe2O4-T400). The rheological properties of these MRF samples were then observed at room temperature using a rheometer with a parallel plate at a gap of 1 mm. Dispersion stability tests were also performed to determine the sedimentation ratio of the three CIP-based MRF samples.


RSC Advances ◽  
2015 ◽  
Vol 5 (63) ◽  
pp. 51130-51134 ◽  
Author(s):  
D. Moitra ◽  
S. Hazra ◽  
B. K. Ghosh ◽  
R. K. Jani ◽  
M. K. Patra ◽  
...  

CoFe2O4 nanoparticles, synthesized via a co-precipitation method at 120 °C, exhibited excellent microwave absorption properties, with minimum reflection loss of −55 dB (∼99.99%) at 9.25 GHz.


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