Synthesis of air stable FeCo alloy nanocrystallite by proteic sol–gel method using a rotary oven

Braga, Tiago Pinheiro; Dias, Diego Felix; Sousa, Matheus Falcão de; Soares, J.M.; Sasaki, J. M.

doi:10.1016/j.jallcom.2014.10.074

Cited by 37 publications

(24 citation statements)

References 39 publications

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“…18 For this reason, the sol-gel method has been widely used modulating these properties. 6,[18][19][20][21][22][23][24][25][26][27][28] The sol-gel method allows a larger surface area for the obtained solids, in our study the LiCoO 2 powder. In addition, this technique also enables a smaller Li-ion diffusion length due to the reduced LiCoO 2 Freitas et al 2255 Vol.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of LiCoO2 from Different Precursors by Sol‑Gel Method

Freitas

Siqueira

Costa

et al. 2017

J. Braz. Chem. Soc.

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Lithium cobalt oxide, LiCoO 2 , widely used as cathode in lithium ion batteries was synthesized and their structural and electronic properties investigated. The crystalline powders were prepared by the sol-gel method with four complexing agents: citric acid, glycine, starch and gelatin. These syntheses were compared with the blank test (without complexing agent). The X-ray diffraction and vibrational spectroscopy allowed the identification of the rhombohedral phase LiCoO 2 ( ) as the only or principal crystalline component in all samples. A small fraction of a second phase of cubic spinel Co 3 O 4 was observed in the samples of starch, gelatin and the blank test. The Rietveld refinements showed small structural variations, indicating reduced influence of the complexing agents on the synthesis. The theoretical HOMO-LUMO (highest occupied molecular orbital-lowest unoccupied molecular orbital) gap values are in agreement to those estimated by diffuse reflectance spectroscopy (DRS). The scanning electron microscopy (SEM) showed morphological pattern regardless of the complexing agent used, showing an alternative method.Keywords: LiCoO 2 , sol-gel method, XRD, Rietveld refinement, lithium ion batteries, DFT IntroductionLithium cobalt oxide, LiCoO 2 , has been the focus of many studies regarding their structural and electronic properties. [1][2][3][4][5][6][7][8] This system has interesting electrochemical features that allows a wide use as cathodes of lithium ion batteries. 2,4 The investigation of the structural aspects of the material is a crucial issue to better understand the electrochemical properties of the LiCoO 2 compound. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] For example, the nature of the crystal, its size and shape, are directly related with its electrochemical characteristics. 2 The LiCoO 2 synthesized at low temperatures (LT), below 500 °C, presents a cubic spinel structure ( ), while the synthesis at high temperatures (HT) (above 500 °C), generates the rhombohedral structure with stratified layers ( ). Therefore, several authors usually classify these structures as LT-LiCoO 2 and HT-LiCoO 2 , respectively . 1,2,7,8,[18][19][20][21][22][23][24] The rhombohedral phase is characterized by a structure with alternating layers of cobalt and lithium cations intercalated with oxygen anions. 22 The lithium and cobalt(III) ions are arranged in intercalated layers (Figure 1a). The cobalt(III) ion is located at the octahedral sites, forming a strong bond with the neighboring oxygen anion to constitute the Co−O layers (Figure 1b). Finally, the lithium layers are intercalated between the CoO 2 plans. 1,3,4 The octahedral sites of these layers are occupied by lithium and cobalt(III) ions alternately that forms a sequential stacking with oxygen ion layers in a close packing of the ABCABC type ( Figure 1c). 4,5 This specific stacking arrangement leads to an environment equivalent for all ions, allowing the maximum charge delocalization and the minimal system energy. 1,3,4 The degree of crystal orde...

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Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of LiCoO2 from Different Precursors by Sol‑Gel Method

Freitas

Siqueira

Costa

et al. 2017

J. Braz. Chem. Soc.

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“…Various preparation methods, such as mechanical alloying [16], polyol [17,18,19] and solgel [20,21] process, transmetallation [22], coprecipitation [23], as well as co-reduction [24] with ultrasound assistance [25] have been reported to result in Fe-Co alloy nanoparticles with various Co concentration levels. Due to their large reactive specific surface area, fine metal powders can be susceptible to spontaneous ignition under exposure to air, and consequently they require special precautions regarding their storage and manipulations [26].…”

Section: Introductionmentioning

confidence: 99%

“…Thus, from the point of view of their applicability, long-term stability against oxidation under ambient conditions is an important desirable feature of metallic and alloy nanoparticles. For the case of Fe-Co alloys, sol-gel and polyol processes were recently reported to lead to air-stable nanoparticles [19,21].…”

Section: Introductionmentioning

confidence: 99%

Structure and magnetism of Fe–Co alloy nanoparticles

Klencsár

Németh

Zoltán

et al. 2016

Journal of Alloys and Compounds

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We report the hydrothermal synthesis and structure of Fe x Co 1-x alloy nanoparticles with considerable stability against oxidation under ambient atmosphere. Powder X-ray diffractometry (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), inductively coupled plasma mass spectrometry (ICP-MS), 57 FeMössbauer spectroscopy and magnetization measurements are applied to characterize the composition, morphology, crystal structure, atomic order and magnetic properties of the nanoparticles. As-prepared samples are composed mainly of the bcc Fe x Co 1-x alloy phase.TEM images of heat-treated samples confirm the nanoparticle nature of the original alloys. A consistent analysis of the experimental results leads to x  53% and x  62% Fe atomic ratio respectively in two analogous alloy samples, and suggests that the atomic level structure of the nanoparticles corresponds to that of a fully disordered (A2-type) alloy phase. Exploration of the effect of cobalt on the 57 Fe hyperfine parameters of iron microenvironments suggests that in these alloys the electronic state of Fe atoms is perturbed equally and in an additive manner by atoms in their first two coordination spheres.

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“…Some reports state that the large protein chains present in the coconut water can easily bind the metal salts of the solution to form stable micelles [15,16]. Successful synthesis of gold nanoparticles assisted by a protein mixture [17] and metal oxide nanocrystals using collagen have been recently reported [18], supporting the efficiency of proteins in the production of crystalline nanoparticles. Indeed, metal ions can bind to specific amino acid (aa) ligands of the protein chain depending on the characteristics of the metal ion (e.g., valence state and ionic radius) and the protein chain (e.g., net charge, dipole moment, and polarizability, among others) [19].…”

Section: Introductionmentioning

confidence: 96%

An Eco-Friendly Method of BaTiO₃ Nanoparticle Synthesis Using Coconut Water

Gomes

Magalhães

Paschoal

et al. 2018

Journal of Nanomaterials

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BaTiO 3 nanoparticles were successfully synthesized by a new coconut water-based sol-gel method using Ba(CH 3 COO) 2 and TiCl 3 as the starting salts. The influence of the amount of coconut water and calcination conditions on the barium titanate crystallization was investigated. The resulting nanoparticles were characterized by thermogravimetric and differential thermal analysis, X-ray diffraction, scanning electron microscopy, and Raman and Fourier transform infrared (FTIR) spectroscopies. The ferroelectric tetragonal single phase of BaTiO 3 was obtained in samples prepared with a ratio of coconut water volume (mL)/BaTiO 3 mass (g) of 25 : 2 and 30 : 2, calcined at 1100°C, which was confirmed by XRD measurements. Crystallites with an average size of about 31 nm for both samples were obtained, and microscopy images revealed the presence of particles in the range of 40 to 60 nm. Raman and FTIR spectra confirmed the dominant tetragonal phase of BaTiO 3 , meanwhile traces of BaCO 3 were identified in FTIR spectra.

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Synthesis of air stable FeCo alloy nanocrystallite by proteic sol–gel method using a rotary oven

Cited by 37 publications

References 39 publications

Synthesis and Characterization of LiCoO2 from Different Precursors by Sol‑Gel Method

Synthesis and Characterization of LiCoO2 from Different Precursors by Sol‑Gel Method

Structure and magnetism of Fe–Co alloy nanoparticles

An Eco-Friendly Method of BaTiO₃ Nanoparticle Synthesis Using Coconut Water

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Synthesis of air stable FeCo alloy nanocrystallite by proteic sol–gel method using a rotary oven

Cited by 37 publications

References 39 publications

Synthesis and Characterization of LiCoO2 from Different Precursors by Sol‑Gel Method

Synthesis and Characterization of LiCoO2 from Different Precursors by Sol‑Gel Method

Structure and magnetism of Fe–Co alloy nanoparticles

An Eco-Friendly Method of BaTiO3 Nanoparticle Synthesis Using Coconut Water

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An Eco-Friendly Method of BaTiO₃ Nanoparticle Synthesis Using Coconut Water