Characteristics of Co3O4 and cobalt nanostructured microspheres: Morphology, structure, reduction process, and magnetic properties

Shatrova, Nadezda; Yudin, A. G.; Levina, V. V.; Кузнецов, Денис; Новакова, А. А.; Dzidziguri, É. L.; Перов, Н.С.; Issi, J.‐P.

doi:10.1016/j.materresbull.2017.11.017

Cited by 16 publications

(11 citation statements)

References 49 publications

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“…The coercivity HC of the hollow Fe particles was 157 ± 11 Oe, which was higher than that of carbonyl iron (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)41]). The high HC value was probably caused by the presence of the oxidized surface and defect nanostructure of the particles.…”

Section: Magnetic Propertiesmentioning

confidence: 80%

“…In these papers, nitrate solutions of the Ni and Co (10 wt.%) at 1000 • C were applied as precursors. The 2 of 12 frequency of the ultrasonic generator was 1.7 MHz in the experiment with nickel oxide [7] and 1.7-2.2 MHz in the case of Co [10,11]. The typical diameter of the microspheres of nickel oxide and cobalt oxide was 5-7 µm and 1.5 µm [7,11], respectively.…”

Section: Introductionmentioning

confidence: 92%

“…Recently, the synthesis of nickel oxide [7] and metallic cobalt [10,11] by the spray pyrolysis technique was reported. It was shown that changes in the frequency of ultrasonic atomization and the concentration of the initial salt solution regulates the particle size of the final product [12,13].…”

Section: Introductionmentioning

confidence: 99%

“…The difference in size can be explained by the influence of the frequency of the aerosol generator as well as by differences in surface activity of nickel and cobalt nitrate solutions. In the papers [10,11], cobalt oxide was reduced to the metal in the presence of hydrogen. This two-stage method allows the control of the properties of the product both at a first stage-synthesis of the metal oxide-and at a second stage-reduction of the metal oxide to the metal.…”

Section: Introductionmentioning

confidence: 99%

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Low Weight Hollow Microspheres of Iron with Thin Dielectric Coating: Synthesis and Microwave Permeability

et al. 2020

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Spray pyrolysis of an aqueous solution of iron nitrate, proceeded with reduction of the product in hydrogen, gave iron powder with micron-sized hollow particles. Coating these iron particles with SiO2 through tetraethyl orthosilicate hydrolysis prevented interparticle electrical contacts and suppressed DC percolation. This material shows a high ferromagnetic resonance frequency of 18 GHz, low permittivity, and weighs 20% less than common carbonyl iron. Potential microwave applications are for inductors and electromagnetic interference shielding designs.

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Section: Magnetic Propertiesmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Low Weight Hollow Microspheres of Iron with Thin Dielectric Coating: Synthesis and Microwave Permeability

et al. 2020

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“…Cobalt nanopowders contained the following phases (see Table 2): FCC–Co (face‐centred cubic lattice); CPH–Co (close‐packed hexagonal lattice); Co(OH) 2 ; CoO. The presence of oxide in cobalt nanoparticles produced at 300 and 400°C was associated with secondary oxidation of the material [18]. The presence of cobalt hydroxide and cobalt oxide in the sample obtained at 200°C was associated with an incomplete reduction of the material.…”

Section: Resultsmentioning

confidence: 99%

Low‐temperature oxidation of metal nanoparticles obtained by chemical dispersion

Dzidziguri

Сидорова

Yahiyaeva

et al. 2020

Micro & Nano Letters

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Oxidation of cobalt, nickel, molybdenum and tungsten nanoparticles under prolonged exposure in the air was studied. Nanoparticles were obtained by chemical dispersion with the following reduction temperatures: 200-400°C for cobalt; 200-400°C for nickel; 700-800°C for molybdenum and 750-850°C for tungsten. Scanning electron microscopy, transmission electron microscopy, XRD and thermogravimetric analysis were used for nanoparticles characterisation. The average size of nanoparticles, specific surface area and the coherent scattering area were determined. The method for oxide film thickness calculation on the surface of the nanoparticles was proposed and confirmed its adequacy. Based on experimental data, the growth law of the oxide film on the studied nanoparticles was determined. The obtained results can be used in the certification of nanoparticles and evaluation of a highly dispersed metal powders shelf life.

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Fast and continuous obtaining of Eu3+ doped CeO2 microspheres by ultrasonic spray pyrolysis: characterization and photocatalytic activity

Santiago

Neto

Longo

et al. 2019

J Mater Sci: Mater Electron

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In this work, CeO 2 :xEu 3+ (x = 0, 0.01, 0.02, 0.04 and 0.08 mol%) microspheres were obtained by the fast and continuous ultrasonic spray pyrolysis method. Powders were characterized by X-ray diffraction (XRD), X-ray fluorescence analysis (XRF), scanning electronic microscopy (FESEM), Raman spectra, UV-Visible spectroscopy (UV-Vis) and photocatalytic activity. All XRD patterns were indexed by the cubic structure of the fluorite type, without the presence of secondary phases, indicating success in the Eu 3+ doping in the CeO 2 structure. In addition, The XRF analysis confirmed the presence of Eu in the CeO 2 powders. In the Raman spectra of the samples occurs the vibrational mode F 2g , which is a characteristic band of materials with the fluorite type structure. Moreover, as the Eu 3+ ion increased, it was noticed the appearance of additional bands referring to oxygen vacancies. FESEM showed that the CeO 2 :xEu 3+ particles have a spherical morphology with homogeneous chemical composition and particle size between 73 and 1560 nm. It can be seen a slight increase of defects in their morphology as the Eu 3+ ion increases. The band gap varies between 3.22 and 3.28 eV, being influenced by defects in oxygen vacancies and the concentration of Ce 3+ ion. The addition of Eu 3+ generates the introduction of intermediary levels in the conduction band of CeO 2 , besides increasing the reactive species effects, favoring the photocatalysis of Rhodamine B dye.

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Characteristics of Co3O4 and cobalt nanostructured microspheres: Morphology, structure, reduction process, and magnetic properties

Cited by 16 publications

References 49 publications

Low Weight Hollow Microspheres of Iron with Thin Dielectric Coating: Synthesis and Microwave Permeability

Low Weight Hollow Microspheres of Iron with Thin Dielectric Coating: Synthesis and Microwave Permeability

Low‐temperature oxidation of metal nanoparticles obtained by chemical dispersion

Fast and continuous obtaining of Eu3+ doped CeO2 microspheres by ultrasonic spray pyrolysis: characterization and photocatalytic activity

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