MgFe2O4 Nanoparticles Research Articles

Magnesium Spinel Ferrites Development for FDM 3D-Printing Material for Microwave Absorption

The magnesium nanosized ferrite powder with formula MgFe2O4 was synthesized via a pyrochemical sol–gel glycine–nitrate method and annealed consistently at temperatures of up to 1300 °C. The MgFe2O4 ferrite samples’ microstructure was studied by SEM and XRD methods. According to the results of the studies, the increase in MgFe2O4 nanoparticles size from about 15 nm to micron-sized particles was observed when increasing annealing temperatures. The DC electrical conductivity of MgFe2O4 also clearly shows the change in conduction behavior of samples with increased calcination temperatures. The electromagnetic microwave properties of micron-sized particles of MgFe2O4 ferrite powder for a 1200 °C annealing temperature were studied for composites in paraffin matrix with produced magnetic filler mass concentration at 40% and 50%. The filament composites of polymer polylactic acid with MgFe2O4 ferrite powder samples were prepared by the FDM 3D-printing process and their microwave-absorbing properties were investigated. The application of developed PLA–MgFe2O4 ferrite filament for fabricating magnetic microwave-absorbing components also was demonstrated.

Effects of synthesized AlFe2O4 and MgFe2O4 nanoparticles on biogas production from anaerobically digested sugar refinery wastewater.

The application of magnetic nanoparticles (MNPs) toward sustainable water economy and bioenergy production has become a subject of great interest. Anaerobic digestion (AD) has been widely exploited in wastewater treatment settings, whereby utilization of MNP additives by microorganism response for degradation of organics into biogas is seen to be eco-friendly and economically viable. The present study investigated the impact of two synthesized MNPs such as aluminum ferrite (AlFe2O4) and magnesium ferrite (MgFe2O4) on biogas production via biochemical methane potential (BMP) tests. A BMP set-up of three (3) bioreactors was tested with a working volume of 0.8 L which comprises 0.5 L wastewater (WW) and 0.3 L activated sludge (AS) with 1.5g of the MNPs and a control system without MNPs. The degradation of chemical oxygen demand (COD) was increased with set-ups that contained MNPs as compared to the control system, MgFe2O4 (93.96%) > AlFe2O4 (85.95%) > control (68.83%). In terms of biogas production, the methane yield was also recorded as MgFe2O4 (85.7%) > AlFe2O4 (84.3%) > control (65.7%). The physical and chemical stability of MNPs makes them more advantageous for application in biogas production. In the prospects of biogas enhancement and biodegradability, integrating MNPs in an anaerobic digestion system will result in a more efficient anaerobic process performance for biogas production.

Magnesium Ferrite/Poly(cysteine methacrylate) Nanocomposites for pH-Tunable Selective Removal and Enhanced Adsorption of Indigo Carmine and Methylene Blue

Magnesium ferrite (MgFe2O4) and silica-coated MgFe2O4 nanoparticles were grafted with poly(cysteine methacrylate) (i.e., MgFe2O4/PCysMA and MgFe2O4@SiO2/PCysMA nanocomposites) to study pH-tunable adsorption and enhanced capacities for the adsorption of anionic indigo carmine (IC) and cationic methylene blue (MB) dyes. Several characterization techniques (i.e., XRD, FTIR, TGA, ζ potential analysis, VSM, FE-SEM, TEM, N2 adsorption–desorption isotherm, and XPS) indicated successful syntheses of these nanocomposites. The adsorption behaviors of the dyes demonstrated that the PCysMA-modified nanoadsorbents could selectively adsorb either IC or MB from either single-component or binary dye systems if the initial pH of the dye solution was tailored appropriately (i.e., pH ∼2 for IC and pH ∼10 for MB). The selective adsorption of these dyes was proposed by the electrostatic attractions of the nanoadsorbents and the dyes. Adsorption isotherms also showed enhanced capacities of MgFe2O4 and MgFe2O4@SiO2 NPs for the adsorption of IC and MB after grafting with PCysMA. Interestingly, the MgFe2O4@SiO2/PCysMA nanoadsorbent provided highly pH-selective adsorption and large increases in the capacities for the adsorption of IC and MB, which were attributed to the amounts of PCysMA grafted onto different magnetic substrates. The coating of silica on the surfaces of magnetic nanoparticles provided a higher amount of 3-methacryloxypropyltrimethoxysilane, promoting the polymerization of CysMA monomer. Recycling tests indicated that high efficiencies (∼80%) for the adsorption of IC and MB by the PCysMA-modified nanoadsorbents were obtained after five adsorption–desorption cycles. These key findings showed that the MgFe2O4/PCysMA and MgFe2O4@SiO2/PCysMA nanocomposites exhibited excellent pH-tunable adsorption of anionic and cationic dyes, easy magnetic separation, good reusability, and high stability. Specifically, the MgFe2O4@SiO2/PCysMA nanocomposite offers highly pH-selective adsorption and high adsorption capacities for dyes, demonstrating promising and alternative nanoadsorbents for applications in wastewater treatment and sensors.

Investigation of capacitors and electrical circuit elements performance of magnetic biocomposites prepared by using the hemp biomass

Hemp biomass (HB) was brought into activated hemp biomass (AHB) by chemical technique and all samples were obtained by doping different nanoparticles. Structural, dielectric and magnetic characterizations for all samples were performed by using the XRD, FTIR, SEM, EDX, LCR Meter and PPMS at room temperature. The characteristics of both hemp biomass and nanoparticles in the structures of these samples were examined in detail. In addition to HB and AHB samples, the contribution of lignin and pectin characteristic bands to conductivity was investigated in AHB samples doped with Fe3O4, MgFe2O4 and SrFe2O4 nanoparticles. It has been determined that homogeneously dispersed nanoparticles contribute to surface area, crystallization and conductivity and these samples are technological products. It was determined that the samples could be used as batteries, and two electrical circuits simultaneously connected to the lignin and pectin structures of the activated hemp biomass (AHB) doped with different types of nanoparticles were obtained from the Smith-Chart diagram.

Hydrogel beads based on carboxymethyl cassava starch/alginate enriched with MgFe2O4 nanoparticles for controlling drug release

Implementing novel oral drug delivery systems with controlled drug release behavior is valuable in cancer therapy. Herein, a green synthetic approach based on the sol-gel technique was adopted to prepare MgFe2O4 nanoparticles at different calcination temperatures using citric acid as a chelating/combustion agent. In this context, pH-responsive and magnetic carboxymethyl starch/alginate hydrogel beads (CMCS-SA) containing the MgFe2O4 nanoparticles were developed as potential drug carriers for the anticancer drug (Doxorubicin, Dox) release in simulated gastrointestinal fluids. Furthermore, in vitro release behaviors validated that these beads illustrated excellent stability in the simulated stomach liquids. In contrast, the data in simulated intestinal fluids showed sustained release of Dox because of their pH-sensitive swelling characteristics. Notably, applying an external magnetic field (EMF) could accelerate drug release from the beads. The in vitro release of drugs from gel beads was mainly accomplished by a combination of diffusion, swelling and erosion. Moreover, the cell cytotoxicity test and laser confocal results showed no harmful effects on normal cells (3T3) but were significant cytotoxic to colon cancer cell lines (HCT116) by drug-loaded hydrogel beads. Therefore, the prepared gel beads could be qualified as latent platforms for controlling the release of anticancer drugs in cancer treatment.

X-ray diffraction, magnetic measurements and Mössbauer spectroscopy of MgFe2O4 nanoparticles

Magnesium ferrite (MgFe2O4) was synthesized using the solution combustion method. The concentration of the fuel was varied and investigated its effect on spectroscopic, structural and magnetic properties of MgFe2O4 nanoparticles. The XRD pattern showed a decrease in the crystallite size and increase in the lattice strain, dislocation density and specific surface area upon increasing the fuel amount. The shift in the FTIR band (~434 cm–1) corresponds to the Fe–O vibration in the octahedral sites. The values of HC decreased while Mr values increased continuously with the increase of the fuel concentration. The Mössbauer spectra of MgFe2O4 nanoparticles measured with a high velocity resolution demonstrated a large number of magnetic sextets assigned to the tetrahedral (A) and octahedral [B] sites. These magnetic sextets were considered as a result of different Fe3+ local microenvironments depending on Mg2+ cations distributions among the neighboring (A) and [B] sites. The calculations of binomial distribution of the probabilities of the numbers of Mg2+ cations within the sphere of 3.7 Å around Fe3+ cations in both (A) and [B] sites demonstrated distributions of different probabilities for these sites in agreement with the Mössbauer spectra fits. The numbers of magnetic sextets and their hyperfine parameters assigned to the (A) and [B] sites were found slightly varied for MgFe2O4 nanoparticles prepared with different fuel concentrations.

Experimental evidence of exchange forces between nanoparticles in a superparamagnetic system

Although interacting superparamagnetic systems have been widely explored, in most cases the correlations are only assigned to dipolar interactions. Here, we perform a systematic investigation of the properties of superparamagnetic MgFe2O4 nanoparticles, a system with characteristics that led us to believe they are associated with the existence of exchange interactions in the system. We first confirm that our sample consists of pure MgFe2O4 nanoparticles, having an average size of ∼12 nm and superparamagnetic behavior at room temperature with an irreversibility temperature of 250 K. Nevertheless, we reveal that the magnetic response is not well described by the Langevin function, even when taking into account the size distribution of the nanoparticles. In order to address the reasons for such deviation from the non-interacting behavior of a superparamagnetic system, we focus our attention on equilibrium and dynamic magnetization measurements, and consider a theoretical approach in the context of mean-field approximation, in which the effects of interactions in the sample are investigated. From the results, we find a positive value of 243 K for the parameter Θ associated with the mean field. Such a condition imposes the existence of magnetizing effects due to interactions in the system, which, according to Weiss’ mean field theory, are a fingerprint of the presence of exchange forces between nanoparticles.

Kinetics and Adsorption Isotherms of Amine-Functionalized Magnesium Ferrite Produced Using Sol-Gel Method for Treatment of Heavy Metals in Wastewater.

This study is focused on the kinetics and adsorption isotherms of amine-functionalized magnesium ferrite (MgFe2O4) for treating the heavy metals in wastewater. A sol-gel route was adopted to produce MgFe2O4 nanoparticles. The surfaces of the MgFe2O4 nanoparticles were functionalized using primary amine (ethanolamine). The surface morphology, phase formation, and functionality of the MgFe2O4 nano-adsorbents were studied using the SEM, UV-visible, FTIR, and TGA techniques. The characterized nanoparticles were tested on their ability to adsorb the Pb2+, Cu2+, and Zn2+ ions from the wastewater. The kinetic parameters and adsorption isotherms for the adsorption of the metal ions by the amine-functionalized MgFe2O4 were obtained using the pseudo-first-order, pseudo-second-order, Langmuir, and Freundlich models. The pseudo-second order and Langmuir models best described the adsorption kinetics and isotherms, implying strong chemisorption via the formation of coordinative bonds between the amine groups and metal ions. The Langmuir equation revealed the highest adsorption capacity of 0.7 mmol/g for the amine-functionalized MgFe2O4 nano-adsorbents. The adsorption capacity of the nanoadsorbent also changed with the calcination temperature. The MgFe2O4 sample, calcined at 500 °C, removed the most of the Pb2+ (73%), Cu2+ (59%), and Zn2+ (62%) ions from the water.

Electrochemical, oxygen evolution reaction and photoelectrochemical water splitting activity of Ca-doped MgFe2O4 nanoparticles

The transition mixed spinel ferrites (SFs) are the components used in the current modern technology and these include better elements whose ionic radii and oxidation state for exploring their electrochemical (EC) - photoelectrochemical (PEC) water splitting properties. In the current work, Ca 2+ - doped MgFe 2 O 4 NPs are synthesized and characterized by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM) to examine the crystal structure and particle size. The EC characteristics such as cyclic voltammetry were used to perform the super capacitive (SC) behavior of Ca 2+ - doped MgFe 2 O 4 electrodes. The cyclic voltammetry measurements analysis confirmed the prepared electrode's EC activity behavior. The current study was performed to examine the EC behavior of Ca 2+ - doped MgFe 2 O 4 electrodes in 1 M KOH electrolytes. The Mg 0.9 Ca 0.1 Fe 2 O 4 revealed a significant specific capacitance (SP) of 221.57 F g −1 at 0.33 A g −1 current density (CD). Accordingly, Mg 0.9 Ca 0.1 Fe 2 O 4 may be employed as a favorable electrode for supercapacitor applications. The oxygen evolution reaction (OER) of Ca 2+ - doped MgFe 2 O 4 electrodes was performed as electrocatalysts in 1 M KOH. The Mg 1−x Ca x Fe 2 O 4 (x = 0.1, 0.3 & 0.5) NPs could be significant agents for PEC water splitting applications. The current study may lead to a new insight into the growth of a new class of mixed transition SFs for energy and environmental applications. • Electrochemical behavior of Ca 2+ doped MgFe 2 O 4 electrodes was performed in 1.0 M KOH electrolytes. • Oxygen evolution reaction of Ca 2+ doped MgFe 2 O 4 electrodes was performed as electrocatalysts in 1 M KOH. • The Mg 1−x Ca x Fe 2 O 4 (x = 0.1, 0.3 & 0.5) NPs could be significant agents for PEC water splitting applications. • Synthesized materials as promising electrodes and catalysts for energy storage and environmental remediation.

Synthesis and characterization of MgFe2O4 nanoparticles and PEG-coated MgFe2O4 nanocomposite

The present study aims to synthesize MgFe2O4 nanoparticles with different molar ratio of Mg/Fe by sol-gel following the Pechini route, in addition, MgFe2O4 nanoparticles coated with polyethylene glycol (PEG) were synthesized by the agitation method for their possible use as potential candidates for biomedical applications. The nanoparticles and nanocomposite obtained with this method were characterized by XRD, TGA and DTA, SEM-EDX, TEM, VSM and FTIR. The XRD results show of nanoparticles with Mg/Fe ratio = 0.75 have inverse spinel structure corresponding to pure magnesium ferrite phase. TGA and DTA show average weight losses of 76% in the precursors and indicate the beginning of the formation of the crystalline phase at 500 °C. SEM micrographs reveals the presence of agglomerates of nanoparticles from 1 to 7 μm and EDX spectrum revels the presence of Mg, Fe, O and C elements. TEM analysis corroborates the presence of the pure phase of MgFe2O4 with spherical morphologies and average particle size of 36 nm. While, the coated nanoparticles presented a weight loss of 11% attributed to the nature of coating, presence of agglomerates with sizes of 1 μm by SEM, and spherical morphologies and average sizes of 25 nm by TEM. In addition, the magnetic properties reveal the superparamagnetic behavior with saturation magnetization (Ms) in the range of 16–17 emu/g at 25 °C. Finally, FTIR spectra showed the characteristic vibrational frequencies of MgFe2O4 nanoparticles and polymer coating (PEG).

Magnesium ferrite-nitrogen-doped graphene oxide nanocomposite: effective adsorptive removal of lead(II) and arsenic(III).

Magnetic nanocomposites have received immense interest as adsorbents for water decontamination. This paper presents adsorptive properties of nitrogen-doped graphene oxide (N-GO) with magnesium ferrite (MgFe2O4) magnetic nanocomposite for removing lead(II) (Pb(II)and arsenite As(III) ions. Transmission electron microscope (TEM) image of synthesized nanocomposite revealed the wrinkled sheets of N-GO containing MgFe2O4 nanoparticles (NPs) with particle size of 5-15nm distributed over its surface. This nanocomposite displayed higher BET surface area (72.2 m2g-1) than that of pristine MgFe2O4 NPs (38.4 m2g-1). Adsorption on the nanocomposite could be described by the Langmuir isotherm with the maximum adsorption capacities were 930mg/g, and 64.1mg/g for Pb(II) and As(III), respectively. Whereas, maximum removal efficiencies were observed to be 99.7 [Formula: see text] 0.2% and 93.5 [Formula: see text] 0.1% for Pb(II) and As(III), respectively. The study on the effect of coexisting anions on the adsorption of metal ions showed that the phosphate ions were potential competitors of Pb(II) and As(III) ions to adsorb on the nanocomposite. Significantly, the investigation on adsorption of metal ion in the presence of coexisting heavy metal ions indicated the preferential adsorption of Pb(II) ions as compared to Cd(II), Zn(II) and Ni(II) ions. The effectiveness of the nanocomposite to remove the metal ions in electroplating wastewater was demonstrated.

Mechanistic insight into adsorption and photocatalytic potential of magnesium ferrite-bentonite nanocomposite

Magnesium ferrite (MgFe2O4)-bentonite nanocomposite is a clay based nanoadsorbent and photocatalyst with immense potential in water remediation. In the present study, adsorption and photodegradation mechanisms for nanocomposite were explored using Cd (II) and martius yellow as model contaminants. XRD, FT-IR, TEM and SEM-EDS studies of nanocomposite confirmed the presence of MgFe2O4 nanoparticles over the bentonite layers. The linear and nonlinear regression analyses were employed to accurately predict the mechanism and the results were validated statistically. The equilibrium data for Cd (II) ions and martius yellow was best represented by linear Langmuir isotherm. The optimization of models depicted the monolayered adsorption. The kinetics of both the adsorption and photodegradation processes followed the linear pseudo-second-order kinetic model, which specified the interaction of the adsorbates with two active sites of the adsorbent. The synthesized nanocomposite showed the maximum adsorption capacities of 1073.3 mg g−1 and 789.6 mg g−1 for Cd (II) ions and martius yellow, respectively. The adsorbed Cd (II) ions had synergistic effect on the degradation of martius yellow. Degradation mechanism of martius yellow was predicted on the basis of GCMS analysis and quenching studies. Thermodynamic studies, adsorption modeling and XPS analysis helped in predicting the adsorption mechanism. The regeneration studies confirmed the stability and recyclability of the nanocomposite. The present studies provided detailed account of mechanism of adsorption and photocatalysis for magnesium ferrite-bentonite nanocomposite, which has practical implication for environmental applications.

ZIF-8-incorporated nanoparticles of MgFe2O4 supported on graphene oxide: A ternary hybrid catalyst for the efficient synthesis of pyrazole-based pyrido[2,3-d]pyrimidine-diones

An efficient and stable MgFe2O4 nanoparticles incorporated in zeolitic imidazolate framework-8 supported on graphene oxide (GO) was synthesized. Using the achieved heterogeneous catalyst including ZIF-8@GO@MgFe2O4, various pyrazolo[4′,3′:5,6]pyrano[2,3-d]pyrimidine-dione derivatives were synthesized through the one-pot five-component reaction of hydrazine hydrate, ethyl acetoacetate, 1,3-dimethyl barbituric acid, ammonium acetate, and aryl aldehydes in the absence of any solvent. Furthermore, it was found that such a new heterogeneous catalyst was simply recyclable and separable. This research introduces a green and suitable versatile to synthesize a class of organic compounds by simple work-up, facile recycling system, excellent yields, utilizing non-toxic materials, as well as short reaction times. X-ray diffraction spectroscopy (XRD), Furrier transforms infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDX/Mapping), field emission scanning electron microscopy (FE-SEM), and Brunauer-Emmett-Teller (BET) analysis were used to characterization and structure elucidation of the catalyst.

Synthesis and characterization of ultrasmall MgFe2O4 nanoparticles down to the quantum dot scale

Synthesis and characterization of ultrasmall MgFe2O4 nanoparticles down to the quantum dot scale

MgFe2O4 decoration of g-C3N4 nanosheets to enhance CIP oxidation in visible-light photocatalysis

Pluronic 31R1 and MCM41 were utilized to synthesize mesoporous MgFe2O4/g-C3N4 heterostructures. The employed approach yields a high surface area product (120 m2g-1) with a bandgap (2.58 eV) that allows photocatalysis in the visible light regime. TEM images show an even distribution of spherical MgFe2O4 particles with sizes within the ∼10–15 nm range. Magnetization values of 44.0 emu g−1 for the optimal 3% MgFe2O4/g-C3N4 heterostructure were high compared to what have been reported. The photocatalytic ability MgFe2O4/g-C3N4 nanocomposite was greater than that of pure MgFe2O4 or g-C3N4. A tenfold increase in CIP photooxidation efficiency results from incorporation of MgFe2O4 nanoparticles onto g-C3N4 with a percentage concentration of 0–4%. The optimum photocatalyst concentration used was 1.6 g/L for a fast reaction time of 120 min. CIP photooxidation efficiency when using mesoporous 3% MgFe2O4/g-C3N4 was 100% while it was 10% for pure g-C3N4 and 18% for pure MgFe2O4. High dispersion of spherical MgFe2O4 nanoparticles on the surface of g-C3N4, the high surface area, narrow bandgap, the heterostructure that allows unhindered diffusion of CIP into the pore structure, and the superior charge-carrier separation ability resulted in the enhanced photocatalytic ability. Magnetic properties resin from MgFe2O4 addition facilitate the easy separation of the photocatalyst and allowing its recycling.

Modifying the photocatalytic property of ZnO-based photoelectrodes by introducing MgFe2O4 nanoparticles

Modifying the photocatalytic property of ZnO-based photoelectrodes by introducing MgFe2O4 nanoparticles

Radiation shielding, photoluminescence and antimicrobial properties of Magnesium ferrite synthesized [formula omitted] low temperature solution combustion method

The present communication focuses on the synthesis, characterization of MgFe2O4 (MFO) nanoparticles (NPs) for various applications. The MFO NPs was synthesized by using solution combustion method using urea as a fuel and calcined at 500 °C. To know the phase purity, functional group, surface morphology, structural analysis and energy band gap, the synthesized sample was characterized by using the techniques such as powder X-ray diffraction (PXRD), Scanning electron microscopy (SEM), Fourier transmission infrared spectroscopy (FTIR) and UV–Visible spectrophotometer. The Bragg’s reflection of PXRD confirms the formation of monophasic cubic MFO NPs with Fd−3m space group. The direct energy band gap calculated using Tauc’s relation is found to be 3.1 eV. Further, the X-ray/gamma ray shielding properties of MFO NPs in the energy range 0.081–1.332 MeV using NaI (Tl) detector and multi channel analyser (MCA) were measured. The measured shielding parameters are compared with the theory. Above 400 keV energy of X-ray/gamma ray, the measured shielding parameters agrees well with the theory, whereas slight deviation is observed below 400 keV. This deviation is mainly due to the influence of atomic size of the target medium. Hence, we can conclude that an accurate theory is necessary to explain the interaction of X-ray/gamma with the nano size atoms. The photoluminescence emission spectra consists of peaks at 447, 540 and 627 nm. The CIE and CCT coordinates clearly confirms that the present nanophosphor might find applications in display/cool white light LEDs. Furthermore, antimicrobial activity of synthesized MFO nano-particles are also studied. Viability test was conducted on two food borne pathogens such as Bacilluscereus and Pseudomonasaeruginosa. The material showed poor antimicrobial activity compared to streptomycin. Thus MFO material may unfold new prospects in the fields like shielding of X-ray/gamma ray and display applications but not a good antimicrobial agent.

Synthesis of a novel ternary ZIF-8/GO/MgFe2O4 nanocomposite and its application in drug delivery

In recent year, metal–organic frameworks (MOFs) have been displayed to be a category of promising drug delivery systems because of their crystalline structure, the potential of further functionality, and high porosity. In this research, graphene oxide was synthesized from pure graphite via hummer method and then MgFe2O4 nanoparticles was incorporated into the synthesized ZIF-8 metal–organic frameworks which followed with loading on the surfaces of graphene oxide. In continue, tetracycline as an antibiotic drug was loaded on the surfaces and the cavities of the prepared nanocomposite. The outcomes of this research revealed that 90% of the tetracycline was loaded on the synthesized ZIF-8/GO/MgFe2O4 nanostructure. Next, drug release was done at pH: 5 and pH: 7.4 within 3 days, resulting about 88% and 92% release of the tetracycline, respectively. With using different spectroscopic methods like X-ray crystallography (XRD), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX/Mapping), Fourier transform infrared (FTIR), thermalgravimetric analysis (TGA), and Brunauer–Emmett–Teller (BET), the structure of synthesized materials was confirmed. Furthermore, the antibiotic activity of tetracycline trapped into the ZIF-8/GO/MgFe2O4 was evaluated by agar-well diffusion method on both gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria, which showed good antibacterial results.

Comprehensive study of magnetic and optoelectronic properties of MgFe2O4–TiO2 nanocomposites

Pure MgFe2O4 and TiO2 nanoparticles have been synthesized using co-precipitation and sol-gel method, respectively. A facile ultrasonication method is used to prepare MgFe2O4– TiO2 nanocomposites (NCs) with varying concentration of TiO2. Effect of varying TiO2 concentration in different NCs on microstructural and morphological properties have been investigated using X-ray diffraction (XRD), High Resolution-Transmission Electron Microscopy (HR-TEM) and Fourier transform Infrared (FTIR) analysis. These studies confirm the presence of dominant nanocomposite phases of MgFe2O4 and TiO2 along with two impurity phases, Hematite and Armalcolite, in the synthesized NCs. Impact of TiO2 content and the presence of impurity phases on the magnetic and optoelectronics properties have been discussed comprehensively for future applications. UV–Visible (UV/Vis) and Photoluminescence (PL) spectra yield the band gap of composite to be tuned and quite useful for photocatalytic applications. Magnetic properties of the pure and composite samples are studied using Vibrating Sample Magnetometer (VSM). Further, the electronic and magnetic properties of the powdered samples are explored using Electron Paramagnetic Resonance (EPR) Spectroscopy. Variation in g value, peak-to-peak line width (Hpp), resonance field (Hr) and spin–spin relaxation time (T2) for different samples provide useful information about electronic properties of the composite system.

Microwave Synthesis of Spinel MgFe2O4 Nanoparticles and the Effect of Annealing on Photocatalysis.

Through microwave heating in ethanol and with subsequent annealing, crystalline MgFe2O4 nanoparticles are produced rapidly and in high yields >99%. Under varied annealing temperatures, the degree of Mg and Fe site inversion changes the optical, electronic, and composition of the nanoparticles. A small particle size of ∼10 nm is achievable with the aid of an ammonium salt mineralizer that caps the particles during nucleation and growth. Particles with the lowest inversion parameter and limited sintering upon annealing (at 600 °C) exhibit the greatest production of hydroxyl radicals under visible light illumination. As such, these particles also facilitate the degradation of methylene blue dye faster than those particles annealed at higher temperature and show a rate constant of 0.061 h-1 for degrading 10 ppm methylene blue with 20 mg of catalyst.