Structural and Optical Properties of MAl2O4 Spinel-type Prepared by Solution Combustion Synthesis Method for Photocatalytic Application

In this research, the aluminate spinel type materials, MAl2O4, are synthesised by solution combustion synthesis (SCS) method to investigate the effect of the element (M = Ca and Ba) on their structural, mainly crystallinity and optical properties. The characterisations are examined by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and UV-visible diffuse reflectance spectroscopy (UV-DRS). The XRD and FT-IR results showed the formation of the single-phase spinel structure of CaAl2O4 and BaAl2O4. The band gap energy was investigated using the Tauc method, and the obtained values were 3.93 eV and 3.77 eV for CaAl2O4 and BaAl2O4, respectively. The results showed a good agreement with the data as reported in the literature.

Heat dissipation in Sm3+ and Zn2+ co-substituted magnetite (Zn0.1SmxFe2.9-xO4) nanoparticles coated with citric acid and pluronic F127 for hyperthermia application

In this work, Sm3+ and Zn2+ co-substituted magnetite Zn0.1SmxFe2.9-xO4 (x = 0.0, 0.01, 0.02, 0.03, 0.04 and 0.05) nanoparticles, have been prepared via co-precipitation method and were electrostatically and sterically stabilized by citric acid and pluronic F127 coatings. The coated nanoparticles were well dispersed in an aqueous solution (pH 5.5). Magnetic and structural properties of the nanoparticles and their ferrofluids were studied by different methods. XRD studies illustrated that all as-prepared nanoparticles have a single phase spinel structure, with lattice constants affected by samarium cations substitution. The temperature dependence of the magnetization showed that Curie temperatures of the uncoated samples monotonically increased from 430 to 480 °C as Sm3+ content increased, due to increase in A-B super-exchange interactions. Room temperature magnetic measurements exhibited a decrease in saturation magnetization of the uncoated samples from 98.8 to 71.9 emu/g as the Sm3+ content increased, which is attributed to substitution of Sm3+ (1.5 µB) ions for Fe3+ (5 µB) ones in B sublattices. FTIR spectra confirmed that Sm3+ substituted Zn0.1SmxFe2.9-xO4 nanoparticles were coated with both citric acid and pluronic F127 properly. The mean particle size of the coated nanoparticles was 40 nm. Calorimetric measurements showed that the maximum SLP and ILP values obtained for Sm3+ substituted nanoparticles were 259 W/g and 3.49 nHm2/kg (1.08 mg/ml, measured at f = 290 kHz and H = 16kA/m), respectively, that are related to the sample with x = 0.01. Magnetic measurements revealed coercivity, which indicated that hysteresis loss may represent a substantial portion in heat generation. Our results show that these ferrofluids are potential candidates for magnetic hyperthermia applications.

Synthesis and catalytic properties of nickel (II) - copper (II) ferrite

This work studies the process of formation of the spinel structure of nickel (II) -copper (II) ferrite. A possible mechanism for the formation of single-phase spinel samples is considered. It consists of the stage of formation of chelate complexes of nickel (II), copper (II), iron (III) cations with citric acid and their subsequent thermal decomposition. The materials obtained are studied by X-ray phase analysis and the BET technique. The catalytic activity of the synthesized ferrite Cu0.5Ni0.5Fe2O4 in the process of oxidative destruction of methyl orange in the presence of hydrogen peroxide is established. It is shown that the process is significantly accelerated with increasing temperature. The activation energy of the reaction was computed. It was found that the activation energy decreases in the presence of a catalyst. The results can be used to obtain materials suitable for industrial wastewater treatment using organic dyes in production cycles.

Study on synthesis and characterization of nano scale spinel Mn0.5Fe2.5O4 by micro-emulsion method

The single phase of Mn0.5Fe2.5O4 spinel crystals was prepared by the micro-emulsion method with the oil phase is DGDE (diethylene glycol diethyl ether). The characteristics of the materials have been determined by the X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDX), Scanning electron microscopy (SEM) and Brunaure-Emmet-Teller (BET) nitrogen adsorption and desorption, Vibration sampling magnetometer (VSM), Fourier transform infrared spectroscopy (FTIR). The results showed that the single phase of Fe0.5Mn0.5Fe2O4 crystalline was formed due to the substitution of Fe by Mn in the Fe3O4 crystal lattice and single phase spinel crystal is formed with the size of 6.7 nm, specific surface area ≈ 193 m2.g-1, the saturation magnetization reaches ≈ 27 emu.g-1.

Study on synthesis and characterization of nano scale spinel Mn0.5¬Fe2..5O4 by micro-emulsion method

The single phase of Mn0.5Fe2.5O4 spinel crystals was prepared by the micro-emulsion method with the oil phase is DGDE (diethylene glycol diethyl ether). The characteristics of the materials have been determined by the X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDX), Scanning electron microscopy (SEM) and Brunaure-Emmet-Teller (BET) nitrogen adsorption and desorption, Vibration sampling magnetometer (VSM), Fourier transform infrared spectroscopy (FTIR). The results showed that the single phase of Fe0.5Mn0.5Fe2O4 crystalline was formed due to the substitution of Fe by Mn in the Fe3O4 crystal lattice and single phase spinel crystal is formed with the size of 6.7 nm, specific surface area ≈ 193 m2.g-1, the saturation magnetization reaches ≈ 27 emu.g-1.

Synthesis and characterization of magnetic recyclable Fe-substituted zinc aluminate photocatalysts with enhanced sunlight-driven degradation of industrial dyes

Using the sol-gel auto combustion approach with diethanolamine (DEA) as fuel, a sequence of iron-substituted zinc aluminates, ZnFexAl2−xO4 powders, including variable Fe3+ ion concentrations (0 ≤ x ≤ 2) were effectively created. XRD, FT-IR, SEM, EDS, BET, UV-DRS, and VSM were employed to examine the structures, chemical bonds, morphologies, composition, surface area, and optical properties as well as the magnetic behavior of the collected samples. A single-phase spinel structure was gained for the calcined aluminate powders with different interplanar spacing and crystallite sizes, as revealed by the classification results. The bandgap energy (Eg) of adapted aluminates was in the range of 2.08–3.14 eV, identified as being much lower compared to the pure sample (5.60 eV). Thus, Fe3+-substituted ZnAl2O4 samples could be successfully photoexcited using both ultraviolet and visible light, as suggested by the results. Examination of how the four main pollutant types decay when irradiated by sunlight was carried out to assess the samples and establish photocatalytic activity. These contaminants included phenol rhodamine B (RhB), heteropolyaromatic methylene blue (MB), azoic methyl orange (MO) and methyl red (MR). The performance of photocatalytic degradation reached 98% after 150 minutes for all optimal samples of organic dyes. Besides, each of the altered photocatalysts could be recycled and displayed high stability. The S-shaped curve of ferrimagnetism can result from in those samples as found by the magnetic measurements, though pure ZnAl2O4 displays diamagnetic characteristics. The adapted samples show intense improvement in the remanent magnetization (Mr) when compared to pure ZnAl2O4, signifying that magnetic photocatalyst recovery by applying an external magnetic field is easy. Thus, these results offer a convincing sign that ZnAl2O4 powders replaced by Fe3+ could provide the ability to aid in the ecologically-friendly collection of solar energy.

Synthesis and Characterization of Cobalt Ferrite through Co-Precipitation Technique

The device formation in current technology demands effective magnetic materials. Cobalt ferrite nanoparticles were synthesized by the co–precipitations method using the precursor materials (Fe(No3)3 9H2O) and (Co(NO3)2 6H2O). X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) analysis, and UV–Visible absorption spectral studies were used to analyze the structural, chemical/functional groups with possible stretching and optical bandgap properties of the CoFe2O4 powder. XRD results designate that the resultant particles are crystalline, pure single-phase spinel structure. From the FTIR analysis reveals that C-C, C=O stretching, and the shift is leaked indicating that the presence CoFe2O4. The absorption and the optical band gaps values are increased trend with temperatures also evidence that is enhancing magnetic behavior.

Effect of MgO and K2O on High-Al Silicon–Manganese Alloy Slag Viscosity and Structure

The viscosity, melting proprieties, and molten structure of the high-Al silicon–manganese slag of SiO2–CaO–25 mass% Al2O3–MgO–MnO–K2O system with a varying MgO and K2O content were studied. The results show that with the increase in MgO content from 4 to 10 mass%, the measured viscosity and flow activation energy decreases, but K2O has an effect on increasing those of slags. However, the melting temperature increases due to the formation of high-melting-point phase spinel. Meanwhile, Fourier transform infrared (FTIR) and X-ray photoelectron spectra (XPS) were conducted to understand the variation of slag structure. The O2− dissociates from MgO can interact with the O0 within Si–O or Al–O network structures, corresponding to the decrease in the trough depth of [SiO4] tetrahedral and [AlO4] tetrahedral. However, when K2O is added into the molten slag, the K+ can accelerate the formation of [AlO4] tetrahedra, resulting in the increase in O0 and O− and the polymerization of the structure.

Heating Efficiency of CoFe2-xRExO4 (RE=Dy, Yb, Gd) Magnetic Nanoparticles for Hyperthermia Applications

Cobalt ferrite nanoparticles (NPs) doped with rare earth (RE) metals with general formula CoFe2-xRExO4 (RE=Yb, Dy, Gd; x = 0.0 - 0.3) were synthesized by the co-precipitation method followed by post thermal treatment. The influence of RE doping on structural, magnetic and thermal properties and potential biomedical applications like magnetic hyperthermia has been investigated. In the as-prepared samples RE cations enter the spinel lattice as detected by X-ray diffraction. Thermal treatment leads to thermodynamically stable and relaxed single-phase spinel structures only for lower RE content, x = 0.01-0.05. However, annealed samples present higher mass magnetization values (MS), up to 83 Am2/kg. RE content also affects MS, especially in the case of annealed samples where it decreases linearly with x from about 80 Am2/kg (x = 0.01) to about 60 Am2/kg (x = 0.30). Thermal treatment induces a reduction in coercivity from 60-100 mT for as-prepared samples to 18-33 mT for annealed samples, in a nonlinear manner with respect to RE content. Heating efficiency, i.e., Specific Loss Power (SLP), of all samples has been studied using both magnetometric and calorimetric method to deeper examine the energy loss mechanisms involved.