Synthesis Of Spinel Ferrites Research Articles

Synthesis of spinel ferrites from cashew gum for microwave devices application

Synthesis of spinel ferrites from cashew gum for microwave devices application

Synthesis of spinel ferrites and application in the photodegradation of Rhodamine in water via pH control assistance

Nanostructured powders of cobalt ferrite with stoichiometry CoxFe3-xO4, where 0.4 ≤ x ≤ 1.2, were synthesized by the wet chemical route from the Co-precipitation method. Single-phase and crystalline nanopowders of spinel type structure with cubic symmetry and space group Fd3‾m were characterized by X-ray diffraction. The structural refinement was carried out by the Rietveld Method showing a transition of normal spinel to an inverse spinel, as a function of Co2+concentration. Both spectra, Infrared Spectroscopy and Diffuse reflectance spectroscopy were used to characterize chemical bonds Co2+ in tetrahedral coordination, for higher cobalt concentration, and band gap analysis, respectively. The photoactivity of powders was evaluated from the photodegradation of the Rhodamine 6G dye under UV light. CoFe2O4 nanoparticles showed the best photocatalytic degradation with 90.9% in an alkaline medium, which obeys a pseudo-first order kinetic reaction, being the maximum apparent rate constant equal to 10.23 × 10−3. Effects of the occupation of tetrahedral and octahedral sites in the spinel structure in the photoactivity parameter are discussed.

Effects of Ni2+-Substitution on Structural, Magnetic and Electrical Properties of Cadmium Spinel Ferrite Nanoparticles via Chemical Route

Ni2+ substituted spinel ferrites with formula CdxNi1-xFe2O4 were prepared by microwave Sol-gel method. The XRD analysis of the synthesized ferrite confirms the formation of cubic spinel structure of ferrite. Rietveld refined XRD patterns revealed the cubic spinel phase with Fd-3m space group. The oxygen position and the cation distribution are determined by means of Rietveld analysis, indicating the existence of mixed ferrites in each sample. The magnetic properties of all ferrites were studied by using a vibration sample magnetometer. The fast synthesis of spinel ferrites is yielded due to use of the microwave sintering technique.

Gel combustion synthesis and magnetic properties of CoFe2O4, ZnFe2O4, and MgFe2O4 using 6-aminohexanoic acid as a new fuel

For the first time, 6-aminohexanoic acid is used as an alternative fuel in the synthesis of the spinel ferrites with compositions CoFe2O4, ZnFe2O4 and MgFe2O4 using gel combustion synthesis with different oxidizer-to-fuel (O/F) ratios. The gel precursors were studied by differential thermal analysis and thermogravimetry (DTA/TG), which showed that the ignition temperature depends on the gel precursor, being around 230 °C, 130 °C and 275 °C for CoFe2O4, ZnFe2O4, and MgFe2O4, respectively. These results showed than the 6-aminohexanoic acid has an ignition temperature lower than the urea and the citric acid when were used in the synthesis of the spinel ferrites by gel combustion. Moreover, the adiabatic flame temperature (Tad) of the reactions of combustion were calculated using thermodynamic analysis, which showed that Tad increases when the mass of the 6-aminohexanoic acid increases. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques confirmed the formation of the spinel structures for all the O/F ratios, but there is a minor impurity phase for some experiments. The particle morphology was evaluated using scanning electron microscopy (SEM), showing aggregated particles with a sponge-like structure due to the released gases during the combustion. A vibrating sample magnetometer (VSM) was used for measuring the magnetic properties of the as-prepared powders. The values of saturation magnetization, Ms, and coercitivity, Hc, were Ms = 66.9 emu/g and Hc = 1505 Oe for CoFe2O4, Ms = 44.6 emu/g and Hc = 75.2 Oe for ZnFe2O4 and Ms = 28.66 emu/g and Hc = 111.4 Oe for MgFe2O4. The optical band gap for CoFe2O4, ZnFe2O4, and MgFe2O4 were 1.11 eV, 1.37 eV and 1.64 eV, respectively. These results show that 6-aminohexanoic acid can be used as an alternative fuel in the synthesis of spinel ferrites using gel combustion synthesis.

Study on the preparation of spinel ferrites with enhanced magnetic properties using limonite laterite ore as raw materials

Preparation of spinel ferrites using limonite laterite ore as raw materials was proposed. The effect of Zn substitution on the structure, magnetic properties of as-prepared spinel ferrites were systematically characterized and discussed. The results show that single-phase spinel ferrite was directly synthesized from the precursor solution with the leaching temperature and leaching acid concentration of 200 °C and 2.25 mol·L−1, respectively, and after calcination at 1000 °C for 2 h. Moreover, single-phase of spinel ferrites with different Zn substitution contents (x = 0.00, 0.05, 0.23, 0.35, 0.47, 0.58) could be also obtained. All the lattice constant (a), average grain sizes (d) and X-ray density (Dx) increase with increasing Zn substitution content. With Zn substitution content increasing from 0.00 to 0.58, the saturation magnetization (Ms) value increased from 34.0 to 65.9 emu·g−1 for x = 0.35, and then decreased to 50.7 emu·g−1 while the coercivity (Hc) value decreased from 50 Oe to 14 Oe. This paper provides a pathway for comprehensive utilization of limonite laterite ore and synthesis of spinel ferrites with excellent magnetic performance.

Facile Synthesis of Spinel Ferrites with Enhanced Magnetic Properties from Two Intractable Metallurgical Resources: Zinc-Bearing Dust and Nickel Laterite Ore

Nickel laterite ore and zinc-bearing dust are multi-metal-associated and intractable resources. Comprehensive and cooperative utilization of zinc-bearing dust and nickel laterite ore for the preparation of spinel ferrites with enhanced magnetic properties by a facile process was proposed. The structure and magnetic properties of as-prepared spinel ferrites were characterized by X-ray diffraction (XRD), Raman spectroscopy, and Physical Property Measurement System (PPMS). The effect of mass ratios of zinc-bearing dust to nickel laterite ore, calcination temperature, and Zn substitution content on the as-prepared samples was investigated in detail. A single phase of Zn-substituted spinel ferrites (x= 0.00, 0.10, 0.20, and 0.30) could be obtained when the mass ratios were controlled at 1:0.4, 1:4:1.8, 1:2:1.5, and 1:1:1.2 after being calcined at 900 ∘C for 30 min, respectively. The magnetic property tests present that the as-prepared spinel ferrite exhibits enhanced magnetic properties with the saturation magnetization (Ms) value of 66.8 emu g− 1 and the coercivity (Hc) value of 26 Oe when the mass ratio was controlled at 1:1:1.2. This research could provide an effective way to transfer two intractable resources into soft magnetic materials.

Synthesis of sodium-zinc spinel ferrites

The synthesis of spinel ferrites with composition Zn <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-2x</inf> Na <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> Fe <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+x</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> has been performed and the composition range in which single phase samples are obtained has been defined. The characterization of the samples has been carried out from atomic absorption and X-ray fluorescence analyses, X-ray diffraction patterns, Mössbauer spectroscopy and thermomagnetic measurements. It is show that significant loss of Na does exist when the synthesis is performed at high temperatures. When the Na volatilization is avoided spinel oxides with Na content up to 0.25 atoms per unit formula can be obtained. In this case the increase of the interatomic distances leads to differing fundamental magnetic properties as compared to the equivalent lithium-zinc ferrites.