Citrate Auto-combustion Method Research Articles

Graphene-based Sm-doped Co-ferrite for environmental applications

A graphene-based Sm-doped Co-ferrite CoSmFe-G nanosample was created using the citrate auto-combustion method. It acts as an antibacterial agent and heavy metal remover. The sample’s physical properties were analyzed using various techniques including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, scanning electron microscopy (FE-SEM), zeta potential, and vibrating sample magnetometer (VSM) measurements. The XRD results confirmed the presence of a single-phase cubic spinel structure. The experimental results indicated that doping with graphene and samarium significantly altered the magnetic properties of CoSmFe-G nanoparticles, reducing the saturation magnetization (MS) values to 35.759 emu/g. The sample showed antibacterial properties against both gram-positive and gram-negative bacteria, with inhibition zones measuring 12–14.5 mm in diameter. Additionally, the sample exhibited efficient (Pb2+) adsorption, with a maximum removal capacity of 99.8% and a multilayer adsorption mechanism indicated by the pseudo-second-order isotherm and Freundlich model matching. The study explores the binding interactions for lead removal and highlights the potential of using graphene-based Sm-doped Co-ferrite (CoSmFe-G) nano samples as a bio-adsorbent and antibacterial agent. This could lead to practical and efficient solutions for water disinfection.

Enhanced dielectric properties of co-substituted M-type Sr-La hexaferrite synthesized by citrate auto-combustion method

In this present research, comparative analysis of dielectric and electrical properties of M−type lanthanum-strontium (La-Sr) hexaferrites substituted with Co-Zr, Mn-Zr and Ni-Zr with chemical formulae: Sr0.85La0.15(CoZr)xFe12-2xO19, Sr0.85La0.15(MnZr)xFe12-2xO19 and Sr0.85La0.15(NiZr)xFe12-2xO19 (where x is 0.00 to 1.00 with ratio of 0.25) respectively have been investigated in 1 kHz to 1 MHz frequency range. The dielectric constant and loss tangent are generally shows decreasing trend with frequency and AC conductivity shows increasing trend with it. Dielectric constant, tangent loss and AC conductivity are increased with increase in substitution of Co-Zr and Mn-Zr doped La-Sr ferrites but shows opposite trend for Ni-Zr doped La-Sr hexaferrites. The higher electron exchange between ferrous cations (Fe2+) and ferric (Fe3+) cations are responsible for the higher polarization in ferrites. These newly synthesized ferrites have great potential for microwave absorbing material and microwave components

Electromagnetic radiation suppressor based on Co-Ti doped strontium lanthanum hexaferrite for Ku-Band applications

In this proposed work, we report Co-Ti doped Strontium-lanthanum M−type hexaferrites with general chemical formula, Sr0.85La0.15(CoTi)0.5Fe11O19 and Sr0.85La0.15(CoTi)0.75Fe10.5O19 prepared by citrate auto-combustion method. Complex permittivity, complex permeability and microwave absorptive properties of fabricated ferrite compositions were analysed in 12.4 to 18 GHz frequency range (Ku-Band). The XRD (X-ray diffraction) pattern of Co-Ti substituted compositions show single-phase M−type hexagonal ferrite indicating this co-substitution maintained the crystal phase structure. The grain diameter (average) decreased from 587 nm to 290 nm and 415 nm to 318 nm for ferrite samples with composition x = 0.50 and x = 0.75 respectively after 20 hours of ball-milling. The reflection loss (RL) exhibited the absorption bandwidth of more than 90 % (−10 dB) of value 2.41 GHz and 1.2 GHz for fabricated ferrites with chemical composition Sr0.85La0.15(CoTi)0.5Fe11O19 and Sr0.85La0.15(CoTi)0.75Fe10.5O19 respectively.. Both dielectric loss tangent and magnetic loss tangent contributed to enhance total loss tangent which represents microwave absorbing properties of the prepared ferrite samples. Reflection coefficient (S11) values for open circuit method also shows absorption bandwidth (−10 dB) of more than 90 % for these ferrites. Double layer electromagnetic absorber was simulated and observed improved reflection loss and absorption bandwidth. Therefore, these suggested ferrite samples have potential to be used as electromagnetic wave absorbing material of both single and double layer at higher frequency range.

Effect of lanthanide and transition metal on the structure, magnetic, and electric properties of nickel ferrites

A series of nanocrystalline Ni1−xMnxCexFe2−xO4 (x = 0.0, 0.02, 0.04, 0.06, 0.08, and 0.1) were prepared using the citrate auto-combustion method. X-ray diffraction (XRD) indicates that the spinel materials formed in a cubic single phase up to the sample x = 0.02. The average crystallite size is reduced from 61 to 31 nm due to the suppression of grain growth upon cerium occupation at the octahedral site. The cubic spinel structure was confirmed by Fourier-transform infrared (FT-IR) analysis. Scanning electron microscope (SEM) showed agglomerated and rod-shaped structures at various concentrations. AC conductivity and dielectric properties were measured over a frequency range of 20 Hz to 8 MHz. The AC conductivity increases with an enhancement in frequency. The prepared materials have great potential for utilization in microwave devices. The magnetic parameters were estimated from the measured hysteresis loops at room temperature and 100 K using a vibrating sample magnetometer (VSM), which indicated that the samples were suitable for magnetic memory device applications.

Structural, Surface, Magnetic Study and Application of Nanoparticles CoFe2O4, ZnO and its Nanocomposite

Nanoparticles of CoFe2O4 and ZnO were synthesized using the citrate auto-combustion method. A nanocomposite CoFe2O4/ZnO (70:30) was prepared. XRD verified that the samples were synthesized in nanoscale with crystallite sizes of 66.01, 12.48, and 17.47, respectively. The HRTEM image of CoFe2O4 illustrates the cubic structure. FESEM showed that the shape of CoFe2O4, ZnO, and CoFe2O4/ZnO nanoparticles is nearly spherical in morphology. EDAX measurements illustrated that the samples were obtained with nominal compositions similar to their chemical formula. XPS spectra of the investigated CoFe2O4 confirmed the presence of Co2+ and Co3+ ions, as well as Fe3+ and Fe2+ ions. The saturation magnetization increased for CoFe2O4/ZnO than that of the parent CoFe2O4 due to strong ferromagnetic coupling. Antibacterial activity was recorded for the nanocomposite despite its absence from the two parents.

Structural Interpretation of Sintering Temperature Effect on Optical and Electrical Properties of Pr3+‐Substituted Nickel Ferrites

Herein, the sintering temperature effect on various properties of Pr3+‐substituted nickel ferrites prepared through the sol–gel–citrate autocombustion method is presented. The Rietveld refinement of X‐ray diffraction patterns confirms the formation of the inverse spinel nickel ferrite phase with an additional orthorhombic phase PrFeO3. The crystallinity of those samples is better with a lesser weight percentage of the secondary phase for higher sintered samples. Structural parameters like crystallite size, lattice parameter, microstrain, and bond lengths depend strongly on sintering temperature with an increasing trend. Scanning electron micrographs clearly show the grain growth of the samples with sintering temperature with the formation of a secondary phase at the grain boundaries. The photoluminescence study points to the photocatalytic nature of the compositions. The bandgaps of the samples are calculated using a UV–vis study, which shows an initial decrease in values with increasing sintering temperature. The electrical study confirms the grain and grain boundary contribution to the total conductivity. With higher sintering temperatures, activation energies decrease, but the dielectric loss and saturation dielectric constant tend to increase. The scaling of conductivity and dielectric loss spectra confirm the time–temperature superposition principle.

Investigations on the matrix composite [BiFeO3(BFO)-ZnFe2O4 (ZFO)-SrFe12O19(SFO)]’s magneto-dielectric characteristics and its application of technology

Citrate auto-combustion method was employed to create Bi-perovskite (BFO), Zn-ferrite (ZFO) and Sr-hexaferrites (SFO) nanoparticles, which were then mixed up to form matrix composite which used to separate the lead metal ions from wastewater. Based on XRD peaks, the crystallite size was between 30 and 52 nm. The particles' FTIR spectra clearly show that each synthesized compound has unique functional groups. The samples had agglomeration, with each agglomerate including many grains, as shown by the SEM micrographs. The energy band gap of SFO was enhanced and reduced from 3.5 to 1.5 eV by adding BFO and ZFO. For magnetic study, TC as well as μeff of BFO and ZFO were improved by adding SFO. While the dielectric properties for pure SFO was enhanced after adding BFO and ZFO in the nanocomposite, in this research paper author succeed in preparing nanosample with upgrading magnetic, optical and electric properties more than individual samples’ properties. The synthetic BFO/ZFO/SFO nanocomposite produced impressive results in the treatment of wastewater due to their enormous surface area, regulated size, well-defined structure, and high magnetic, optical and electric properties. Kinetic and isotherm analysis are applied to the experimental results. The high correlation coefficient indicates the adsorption of heavy metal ions, which is described by the Langmuir and Freundlich isotherms (R2). For the 97% removal of Pb (II) from wastewater at a contact duration of 40 min at room temperature and pH 7.

The effect of the rare earth A-site cation on the structure, morphology, physical properties, and application of perovskite AFeO3

In this study, the influence of the rare earth (RE) ions on the structure, morphology, magnetic behavior, dielectric properties, and application of AFeO3 perovskite was studied. The perovskite nanoparticles AFeO3 (A: La, Nd, and Sm) were synthesized using the citrate auto combustion method. The x-ray diffraction (XRD) confirmed that the perovskites have an orthorhombic structure. The samples' crystallite size ranges from 13 to 51 nm. The high-resolution transmission electron microscope (HRTEM) assures that the perovskites are synthesized in the nanoscale. AFeO3 multiferroics have antiferromagnetic behavior. The maximum magnetization (Mm) of the NdFeO3 is two times that of the SmFeO3, owing to the variation in the number of electrons in 4f. The dielectric constant values (ε/) are strongly influenced by the rare earth (RE) element ionic radii, with ε/ increasing as the RE ionic radii increase. The investigated perovskites have semiconductor like behavior. The toxic heavy metal Cr6+ is efficiently removed from water by AFeO3 (A: La, Nd, and Sm). The optimum pH value is observed to be 6, at which the maximum removal efficiencies are 88%, 84%, and 53% for NdFeO3, LaFeO3, and SmFeO3, respectively. The Langmuir and Freundlich isotherm models have been used to fit the experimental data.

Novel multiferroic nanoparticles Sm1−xHoxFeO3 as a heavy metal Cr6+ ion removal from water

Novel multiferroic nanoparticles Sm1−xHoxFeO3 have been prepared using a simple citrate auto-combustion method. According to the X-ray diffraction (XRD) data, the multiferroic samples had an orthorhombic single phase structure. The field emission scanning electron microscope (FESEM) illustrated that the nanoparticles possessed a cotton-like morphology with a porous nature. The vibrating sample magnetometer (VSM) demonstrates the antiferromagnetic (AFM) behavior of the samples. The maximum magnetization (Mm) of Sm0.95Ho0.05FeO3 is five times greater than that of SmFeO3. The ferroelectricity of Sm1−xHoxFeO3 has Г2-spin structure. The antiferromagnetic (AFM) spin canting has a great effect on both the magnetization and the ferroelectricity of the investigated perovskites. Sm1−xHoxFeO3; 0.0 ≤ x ≤ 0.10 samples are concluded to be novel single-phase multiferroic materials capable of adsorbing toxic chromium (Cr6+) metal ions from water. A hydrogen potential of pH 6 is the best condition for precipitating chromium ions. The adsorption of Cr6+ ions on Sm1−xHoxFeO3 was studied using the Langmuir and Freundlich isotherm models.

Role of Gd3+ and Ho3+ doping on the structure, physical properties and applications of ZnO

ZnO, Zn0.97Gd0.03O and Zn0.97Ho0.03O were prepared via a citrate auto-combustion method. X-ray diffraction (XRD) demonstrated that the investigated nanoparticles were prepared in a hexagonal structure, with crystallite sizes averaging between 12 and 60 nm. The morphology of the samples is illustrated by the field emission scanning electron microscope (FESEM) images. The paramagnetic behavior of the investigated nanoparticles is demonstrated by VSM. The value of the optical band gap (Eg) of Zn0.97Gd0.03O was higher than the Eg of ZnO due to the Moss–Burstein effect. Heavy metal Cd2+ ions from water are effectively adsorbed by rare earth-doped ZnO. At pH = 8, Zn0.97Ho0.03O exhibits a maximum removal efficiency of 91%. The Freundlich isotherm model fits the experimental results well.

Impact of GO on Non-stoichiometric Mg0.85 K0.3Fe2O4 Ferrite Nanoparticles

Graphene oxide (GO) nanostructures are systems with many fascinating novel properties that can be used to study new science and have significant promise for applications. In this study, graphene oxide was prepared using the modified Hummer’s method. In addition, potassium ferrite is a good candidate for biomedical application, as iron and potassium are biocompatible and non-toxic materials. Mg0.85K0.3Fe2O4/GO nanocomposites were prepared by the citrate auto-combustion method. The effect of adding GO to Mg0.85K0.3Fe2O4 on structure, morphology, electrical, and magnetic properties was discussed. Samples under investigation were characterized using XRD, infrared spectroscopy (IR), high-resolution transmission electron microscopy (HRTEM), and atomic force microscopy (AFM). The crystallite size of prepared samples was decreased from 28.098 to18.148 nm by increasing GO content. Scanning electron microscope (SEM) confirms the successful adhesion of Mg0.85K0.3Fe2O4 nanoparticles on graphene oxide sheets, which are dispersed in a metal oxide matrix. EDAX analysis confirms the existence of C, O, K, Mg, and Fe elements present in the samples. Magnetic properties were studied by VSM and Faraday's method. GO has a significant effect on the magnetic properties of nanocomposites. For instance, the saturation magnetization and Curie temperature have diverse values, which will be appropriate for numerous applications.

Optimization of magnetic properties of BaTiO3/Li0.5Fe2.5O4 multiferroics prepared via modified low-temperature combustion

Multiferroic (x)BaTiO3/(1 − x)Li0.5Fe2.5O4 (0.0 ≤ x ≤ 1) perovskite/spinel nanocomposite was synthesized using a modified citrate auto-combustion method. Both BaTiO3 (BTO) and Li0.5Fe2.5O4 (LFO) phases along with their composites were successfully characterized using X-ray diffraction, Fourier transformation infrared spectroscopy, and X-ray absorption fine structure spectroscopy. The nanoscale, morphology, and magnetic properties were imaged and acquired using high resolution transmission electron microscopy, atomic force microscopy, and vibrating sample magnetometer. Synchrotron radiation-based elemental selective XAFS technique was performed around Fe K-edge to obtain the selective and the detailed local structural information of Li0.5Fe2.5O4 nanoparticles (NPs). The main remarkable result in this work is the enhancement in the coercivity (HC) of LFO NPs after compositing with BTO particularly at x = 0.6, and at x = 0.8. Based on the collected results, BTO/LFO nanocomposite can be seen as a good candidate for different technological applications including magnetically modulated piezoelectric, safety rechargeable batteries, and multilayer ceramic capacitor.

Cadmium Substitution Effect on Microstructure and Magnetic Properties of Mg-Cu-Zn Ferrites

The microstructure, optical, and magnetic properties of CdxMg0.3-xCu0.2Zn0.5Fe2O4 ferrites prepared by the citrate auto-combustion method were investigated. The samples were analyzed by X-ray diffraction, scanning electron microscopy, UV-Vis spectroscopy, https://soh.iums.ac.ir/uploads/uv-vis_-_2.pptx X-ray energy-dispersive spectroscopy, Fourier-transform infrared spectroscopy, and vibrating sample magnetometer. Rietveld refinement of XRD patterns shows a single-phase cubic structure (space group Fd3¯m) for the samples with x up to 0.20, while the impurity phase of CdO is observed in the samples with x = 0.25, 0.30. As the substitution content increases, the presence of non-magnetic Cd2+ ions in the octahedral site and the migration of Fe3+ions from the octahedral site to the tetrahedral site decreases the saturation magnetization of the samples. Comparison of the bandgap energy of the samples shows an increasing trend with Cd substitution for x up to 0.20 and then decreases, which can be interpreted in terms of changes in the electronic structure of the samples. Improvement in dielectric properties of the samples with increase of Cd2+ content for x up to 0.20 may be attributed to easier transfer and electron exchange between Fe3+and M2+ ions.

Assessing of channel structure and magnetic properties on heavy metal ions removal from water

The synthesis of Li1.1Co0.3Fe2.1O4 ferrite nanoparticles has been synthesized by the citrate auto-combustion method. The distribution of cations on A-site and B-site is studied by X-ray diffraction and High-Resolution Transmission Electron Microscopy. The Williamson–Hall analysis and Debye–Scherrer method are used to study the individual contributions of crystallite sizes on the peak broadening of Li1.1Co0.3Fe2.1O4. The estimated crystallite size of the investigated sample obtained from the Williamson–Hall plot and the Scherrer method agrees well with each other. HRTEM analysis confirms the homogeneous formation of the cubic phase. The calculated height and spacing parameters related to roughness are essential to achieve the efficiency of Li1.1Co0.3Fe2.1O4 to be used in microbatteries, smart windows, smart mirrors, gas sensors, and other applications. According to the obtained data, the Li1.1Co0.3Fe2.1O4 has a spiky surface with kurtosis of the line (Rku) equals 5.5. Additionally, the magnetic hysteresis loop has been clarified using the Vibrating Sample Magnetometer. The double peak characteristic in the Switching field distribution reveals the competition between exchange coupling and strong dipolar interactions. Li1.1Co0.3Fe2.1O4 has employed as a sorbent material for the removal of lead (II) ions from wastewater. The main advantages of the synthesized sample are ease of separation, high adsorption, low cost as well as recycled with notable efficiency. Two models of adsorption isotherms (Freundlich and Langmuir) are utilized to recognize the adsorption mechanism.

The impact of cobalt insertion on the structural and magnetic properties of nonstoichiometric ZnCoxFe1.7O4 (x >0.3) nanoferrites

A single-phase nanoferrite ZnCoxFe1.7O4 (0.37≤ x ≤0.9) system has been prepared via the citrate autocombustion method. Nonstoichiometry has been progressively enhanced in the synthesized samples by increasing the cobalt content. Both XRD patterns and IR spectra have confirmed a pure cubic phase for all as-prepared samples and for that with × = 0.9 sintered at 700°C. Interestingly, the lattice parameter showed a general decreasing trend with increasing x. The determined crystallite size of as-prepared samples ranged from 17 to 30 nm in agreement with the HRTEM images. For as-prepared samples, the M−H loops exhibited nearly superparamagnetic behavior, while antiferromagnetic behavior was observed for the sintered sample. According to the suggested cation distribution, continuous insertion of Co2+ in the formula unit is compensated by both the reduction of Fe3+ cations to Fe2+ ones and the progressive occupation of Zn2+ in the 16c positions.

Tuning the morphology and magnetic properties of single-domain SrFe8Al4O19 particles prepared by a citrate auto-combustion method

Single-domain particles of SrFe8Al4O19 were prepared by thermal treatment of porous products of citrate–nitrate autocombustion at 1200 °C, and the effect of synthesis time on the particle morphology and magnetic properties was estimated. The procedure allows one to obtain SrFe8Al4O19 particles with mean diameters of 100–460 nm and coercivity ranges from 14.5 to 18.4 kOe, while ferromagnetic resonance frequencies vary from 149 to 164 GHz.

Submicron particles of Ga-substituted strontium hexaferrite obtained by a citrate auto-combustion method

Fine particles of SrFe12−xGaxO19 (x = 0–6) were obtained via a citrate auto-combustion route. Their magnetic and microwave absorption properties, as well as the features of the crystal structure were studied in detail.

Effect of Silver Nanoparticles on Properties of Cobalt Ferrites

Ferrite nanomaterials in the form of CoAgxFe2−xO4 (x = 0.0, 0.03, 0.07, 0.1, and 0.2) have been prepared by the citrate autocombustion method. Structural analysis was carried out by x-ray diffraction. Fourier-transform infrared spectroscopy confirmed the formation of a spinel crystal structure. High-resolution transmission electron microscopy revealed the formation of particles with mixed morphologies. The average particle size ranged from 22 nm to 31 nm. Vibrating-sample magnetometry revealed that the saturation magnetization Ms and coercivity Hc were affected by the grain size variation. The electrical properties of the samples were investigated over the frequency range from 102 Hz to 105 Hz. Electric modulus analysis showed that the conduction was due to short-range mobility of charge carriers. The variation of the dielectric loss with frequency at different temperatures indicated two types of conduction mechanism. All these results suggest that the synthesized materials can be recommended for fabrication of exchange spring magnets and electrode materials.

Cation Distribution and Magnetic Properties of Gd+3-Substituted Ni-Zn Nano-ferrites

A series of Gd+3-substituted nanocrystalline Ni-Zn ferrites Ni1-xZnxGd0.1Fe1.9O4 (0 ≤ x ≤ 1) are prepared using a low-temperature citrate auto-combustion method. The cation distribution obtained using powder x-ray diffraction demonstrates an increase in hopping length between magnetic and Zn+2 ions. Cation–oxygen vibrations are identified by FTIR spectra. Effect of Zn+2 ion on the magnetic properties at room temperature is determined from the magnetic moment measured through a vibrating sample magnetometer. The magnetic moment and saturation magnetization obey Yafet–Kittel type magnetization with the highest saturation magnetization for x = 0.2 (≈ 54 emu/g). The low squareness ratio of the samples (0.25–0.12) confirms the uniaxial anisotropy.

Structural, optical, and electrical transport properties of some rare-earth-doped nickel ferrites: A study on effect of ionic radii of dopants

Different rare-earth (Ho, Gd, Sm, Pr, and La)-doped nickel ferrites were prepared through the sol-gel citrate auto-combustion method. Rietveld refinement of the X-ray diffraction patterns confirmed the formation of an orthorhombic impurity phase for each doped sample. Structural parameters, including lattice parameter, crystallite size, microstrain, and different bond lengths, were calculated. Field emission scanning electron micrographs showed spherical grains and the existence of secondary phases for the doped samples. Elemental analysis of each component were performed using energy dispersive X-ray spectra. The shifting of the absorption bands of the Fourier transform infrared spectra depicted the rare earth-to-Fe substitution in octahedral sites of nickel ferrites. The optical band gap decreased with the smaller ionic radii of dopants. The study of ac and dc conductivity provided information about the conduction and dielectric relaxation mechanism and the effect of impurity phases. The electrical conductivity and dielectric study suggested that La- and Sm-doped samples showed the highest resistivity with high losses, whereas Ho- and Gd-doped samples showed moderate resistivity with minimum losses.