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Title: High-yield synthesis and characterization of monodisperse sub-microsized CoFe{sub 2}O{sub 4} octahedra

Abstract

In this study, sub-microsized CoFe{sub 2}O{sub 4} octahedra with a high yield are synthesized via a simple hydrothermal route under mild conditions. The as-prepared products are characterized by conventional techniques of XRD, SEM, TEM, ED and HR-TEM. The results show that the as-synthesized sample exhibits octahedral morphology with a narrow size distribution. The edge size of CoFe{sub 2}O{sub 4} octahedra is estimated to be about 0.10-0.14 {mu}m. The growth process is also monitored by time and temperature-dependent observation. It is found that the reaction temperature has no obvious influence on the product morphology but a significant effect on the size of CoFe{sub 2}O{sub 4} octahedra, while the reaction time determines the final morphology of the product. Moreover, it is displayed that the citrate ions play a key role in the formation of CoFe{sub 2}O{sub 4} octahedra. Furthermore, the possible growth mechanism of the sub-microsized CoFe{sub 2}O{sub 4} octahedra is discussed on the basis of a series of experiments. Magnetic measurements show that sub-micro-sized CoFe{sub 2}O{sub 4} octahedra exhibit obvious ferromagnetic behaviors. The saturation magnetization (M {sub s}), remanent magnetization (M {sub r}), and coercivity (H {sub c}) are determined to be 85.8, 29.2 emu/g and 892 Oe, respectively. - Graphicalmore » abstract: Sub-micro-sized CoFe{sub 2}O{sub 4} octahedra with a high yield are synthesized via a simple hydrothermal route under mild conditions. TEM image shows that the edge size of CoFe{sub 2}O{sub 4} octahedra is estimated to be about 0.10-0.14 {mu}m.« less

Authors:
 [1];  [2];  [3]
  1. Department of Chemistry, Luoyang Normal University, Luoyang 471022 (China)
  2. Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100080 (China), E-mail: syfu@cl.cryo.ac.cn
  3. Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100080 (China)
Publication Date:
OSTI Identifier:
21015671
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 180; Journal Issue: 2; Other Information: DOI: 10.1016/j.jssc.2006.11.003; PII: S0022-4596(06)00588-3; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CITRATES; COBALT OXIDES; COERCIVE FORCE; IRON OXIDES; MAGNETIZATION; MORPHOLOGY; SCANNING ELECTRON MICROSCOPY; SYNTHESIS; TEMPERATURE DEPENDENCE; TRANSMISSION ELECTRON MICROSCOPY; X-RAY DIFFRACTION

Citation Formats

Liu Xianming, Fu Shaoyun, and Zhu Luping. High-yield synthesis and characterization of monodisperse sub-microsized CoFe{sub 2}O{sub 4} octahedra. United States: N. p., 2007. Web.
Liu Xianming, Fu Shaoyun, & Zhu Luping. High-yield synthesis and characterization of monodisperse sub-microsized CoFe{sub 2}O{sub 4} octahedra. United States.
Liu Xianming, Fu Shaoyun, and Zhu Luping. Thu . "High-yield synthesis and characterization of monodisperse sub-microsized CoFe{sub 2}O{sub 4} octahedra". United States. doi:.
@article{osti_21015671,
title = {High-yield synthesis and characterization of monodisperse sub-microsized CoFe{sub 2}O{sub 4} octahedra},
author = {Liu Xianming and Fu Shaoyun and Zhu Luping},
abstractNote = {In this study, sub-microsized CoFe{sub 2}O{sub 4} octahedra with a high yield are synthesized via a simple hydrothermal route under mild conditions. The as-prepared products are characterized by conventional techniques of XRD, SEM, TEM, ED and HR-TEM. The results show that the as-synthesized sample exhibits octahedral morphology with a narrow size distribution. The edge size of CoFe{sub 2}O{sub 4} octahedra is estimated to be about 0.10-0.14 {mu}m. The growth process is also monitored by time and temperature-dependent observation. It is found that the reaction temperature has no obvious influence on the product morphology but a significant effect on the size of CoFe{sub 2}O{sub 4} octahedra, while the reaction time determines the final morphology of the product. Moreover, it is displayed that the citrate ions play a key role in the formation of CoFe{sub 2}O{sub 4} octahedra. Furthermore, the possible growth mechanism of the sub-microsized CoFe{sub 2}O{sub 4} octahedra is discussed on the basis of a series of experiments. Magnetic measurements show that sub-micro-sized CoFe{sub 2}O{sub 4} octahedra exhibit obvious ferromagnetic behaviors. The saturation magnetization (M {sub s}), remanent magnetization (M {sub r}), and coercivity (H {sub c}) are determined to be 85.8, 29.2 emu/g and 892 Oe, respectively. - Graphical abstract: Sub-micro-sized CoFe{sub 2}O{sub 4} octahedra with a high yield are synthesized via a simple hydrothermal route under mild conditions. TEM image shows that the edge size of CoFe{sub 2}O{sub 4} octahedra is estimated to be about 0.10-0.14 {mu}m.},
doi = {},
journal = {Journal of Solid State Chemistry},
number = 2,
volume = 180,
place = {United States},
year = {Thu Feb 15 00:00:00 EST 2007},
month = {Thu Feb 15 00:00:00 EST 2007}
}
  • Single crystalline CoFe{sub 2}O{sub 4} nanoparticles with high coercivity were prepared via a one-step hydrothermal method. The shape and size of the nanocrystals (in the range of 20–100 nm) can be controlled by varying synthesis parameters such as the concentration of NaOH and CTAB. X-ray diffraction and Raman spectra analysis confirmed that all the as-synthesized nanoparticles have a face centered cubic spinel crystal structure. HRTEM observation of particles shows interlayer spacing 0.48 nm of (111) lattice planes. A coercive force up to 5.0 kOe and saturation magnetization of 73 emu/g was achieved at room temperature for the 40 nm CoFe{sub 2}O{sub 4} nanoparticles.
  • The formation mechanism and shape control of monodisperse magnetic cobalt ferrite (CoFe 2O 4) nanocrystals produced by thermolysis of a stoichiometric Co 2+Fe 2 3+-oleate complex in organic solution has been investigated. Synthesis of the pure ternary CoFe 2O 4 inverse spinel phase, without formation of any intermediate binary cobalt and iron oxides, is favored by the close thermal decomposition temperature of the Co 2+-oleate and Fe 3+-oleate precursors. For reaction temperatures between 250 and 320 °C, the nucleation and growth dynamics dictate the size and shape evolution of the nanocrystals. Prenucleation of CoFe 2O 4 occurs at 250-300 °Cmore » but without any growth of nanocrystals, because the monomer concentration is lower than the critical nucleation concentration. For temperatures in the range of 300-320 °C, which is above the thermolysis temperature of the mixed Co 2+Fe 2 3+-oleate complex, the monomer concentration increases rapidly resulting in homogeneous nucleation. Atomic clusters of CoFe 2O 4 with size <2 nm are initially formed at 314 °C that then grow rapidly when the temperature is raised to 320 °C in less than a minute. The shape of the CoFe 2O 4 nanocrystals can be reproducibly controlled by prolonging the aging time at 320 °C, evolving from initial spherical, to spherical-to-cubic, cubic, corner-grown cubic, or starlike shapes. Finally and thus, with careful choice of reaction parameters, such as the precursor concentration and the heating rate, it is possible to achieve large-scale synthesis of shape-controlled monodisperse CoFe 2O 4 nanocrystals with high yield.« less
  • The syntheses and characterization of six monomeric rhenium thiolate complexes and the structural characterization of two useful rhenium starting materials are presented. Pyridine-2-thiol (2), 3,6-bis(dimethyl-tert-butylsilyl)pyridine-2-thiol (3), and pyrimidine-2-thiol (4) were reacted with [Bu{sub 4}N][ReOBr{sub 4}(H{sub 2}O)]{center_dot}2H{sub 2}O (5), [Bu{sub 4}N][ReOBr{sub 4}(OPPh{sub 3})] (6), [ReO{sub 2}(C{sub 5}H{sub 5}N){sub 4}], and [Re(N{sub 2}CO(C{sub 6}H{sub 5}))Cl{sub 2}(PPh{sub 3}){sub 2}] to give [ReO(C{sub 5}H{sub 4}NS){sub 3}] (7), [ReO(C{sub 8}H{sub 12}NSiS){sub 3}] (8), [ReO(OH)(C{sub 11}H{sub 20}NSi{sub 2}S){sub 2}] (9), [Re(N{sub 2}-CO(C{sub 6}H{sub 5}))Cl(PPh{sub 3}){sub 2}(C{sub 5}H{sub 4}NS)] (10), [ReO(C{sub 4}H{sub 3}N{sub 2}S){sub 3}] (11), and [Re(P(C{sub 6}H{sub 5}){sub 3})(C{sub 4}H{sub 3}N{sub 2}S){sub 3}] (12). Crystalmore » structures are reported for the compounds.« less
  • Trace amounts of H/sub 2/O and limited exposure to air of reaction mixtures of UCl/sub 4/ and 12-crown-4, 15-crown-5, benzo-15-crown-5, 18-crown-6, or dibenzo-18-crown-6 in 1:3 mixtures of CH/sub 3/OH and CH/sub 3/CN resulted in the hydrolysis and oxidation of UCl/sub 4/ to (UO/sub 2/Cl/sub 4/)/sup 2/minus//. In the presence of these crown ethers, it has been possible to isolate intermediate products via crystallization of crown complexes of the (UO/sub 2/Cl/sub 4/)/sup 2/minus// ion, the (UCl/sub 6/)/sup 2/minus// ion, and (UO/sub 2/Cl/sub 2/(OH/sub 2/)/sub 3/). The neutral moiety crystallizes as a hydrogen-bonded crown ether complex; however, crown ether complexation of amore » counterion, either an ammonium ion formed during the oxidation of U(IV) or a Na/sup +/ ion leached from glass reaction vessels, resulted in novel crystalline complexes of the ionic species. ((NH/sub 4/)(15-crown-5)/sub 2/)/sub 2/(UO/sub 2/Cl/sub 4/) /times/ 2CH/sub 3/CN, ((NH/sub 4/)(benzo-15-crown-5)/sub 2/)/sub 2/(UCl/sub 6/) /times/ 4CH/sub 3/CN, and ((NH/sub 4/)(dibenzo-18-crown-6))/sub 2/(UO/sub 2/Cl/sub 4/) /times/ 2CH/sub 3/CN have been structurally characterized by single-crystal X-ray diffraction techniques. The results of all the crystal studies are presented in detail. The ammonium ions interact with the crown ethers via hydrogen-bonding and electrostatic interactions. 15-Crown-5 and benzo-15-crown-5 form 2:1 sandwich cations, allowing no H/sub 4/N/sup +//hor ellipsis/(UO/sub 2/Cl/sub 4/)/sup 2/minus// interaction. The dibenzo-18-crown-6 complexed ammonium ions are 1:1 and form bifurcated hydrogen bonds with the chlorine atoms in the (UO/sub 2/Cl/sub 4/)/sup /minus// anion. The formation of (Na(12-crown-4)/sub 2//sub 2/(UO/sub 2/Cl/sub 4/) /times/ 2OHMe and (UO/sub 2/Cl/sub 2/(OH)/sub 2/)/sub 3/) /times/ 18-crown-6 /times/ H/sub 2/O /times/ OHMe has been confirmed by preliminary single-crystal X-ray diffraction studies.« less
  • The hydrothermal reaction of Cs[sub 4]V[sub 2]O[sub 7], V, H[sub 3]PO[sub 4], H[sub 2]O, and Bu[sub 4]NBr in the molar ratio 4.5:1:41:3150:1 at 200[degrees]C for 48 hr yielded the red-brown cesium vanadium phosphate Cs[(V[sub 2]O[sub 3])(HPO[sub 4])[sub 2](H[sub 2]O)], a mixed-valence V(IV, V) species. The structure contains corner-sharing vanadium octahedra and phosphorus tetrahedra with unusual 1-D (-V[sup IV]-O-V[sup v]-O-)[infinity] chains formed from VO[sub 6] octahedra sharing opposite corners. These chains are connected through tridentate bridging (HPO[sub 4])[sup 2[minus]] units to produce a three-dimensional network. The Cs[sup +] cations occupy large channels formed from six vanadium octahedra and six phosphorus tetrahedra.more » At room temperature the material is paramagnetic with one unpaired spin per (-V[sup IV]-O-V[sup v]-O-) unit while complicated anti-ferromagentic ordering is observed below ca. 6 K. Crystal data: monoclinic, P2[sub 1]/n with a = 7.22(1), b = 18.56(1), c = 8.195(6) [angstrom], [beta] = 114.01(6)[degrees], Z = 4, d[sub calc] = 3.233 g cm[sup [minus]3]; structure solution and refinement based on 1088 reflections converged at R = 0.028.« less