Sol-gel Auto Ignition Research Articles

Facile sol–gel synthesis of trivalent Al3+-Gd3+ ions co-doped nanoscale cobalt spinel ferrite for magneto-electronic applications

The magnetic spinel ferrites nanomaterials simultaneously doped with multivalent cations have gained a lot of interest from many researchers during the last decade. Also, the doping of trivalent rare-earth ions in spinel ferrites is promising for many technological applications. Considering these facts, in this work we investigated the trivalent Al3+-Gd3+ ions co-doped cobalt ferrite nanoparticles with nominal composition as CoFe2-2xAlxGdxO4 (x = 0.00, 0.03, 0.05, 0.07, 0.10). The sol–gel auto ignition route assisted by citric acid as a chelating agent was utilized to synthesize the series of nanoparticles. The Rietveld refined X-ray diffraction (XRD) patterns were analyzed to ensure the single-phase formation of nanoparticles with spinel cubic structure. The spherical-shaped grain morphology of the nanoparticles was indicated by scanning electron microscopy (SEM) images. The elemental analysis obtained by energy dispersive X-ray analysis (EDAX) revealed stoichiometric formation of the samples along with high purity. The two prominent frequency modes analogous to the spinel ferrite structure were noted in the infrared spectra assuring the successful formation of all the samples. The soft magnetic behaviour with a lower coercivity of the prepared nanoparticles was confirmed by the vibrating sample magnetometer (VSM) technique. The DC electrical resistivity plots indicated that resistivity decreases with an increase in Al3+-Gd3+ co-doping. The dielectric studies of all the samples showed increasing behaviour with an increase in Al3+-Gd3+ co-doping. All the results suggest that the Al3+-Gd3+ co-doped cobalt ferrite nanoparticles can be useful for real-world applications, specifically in nanoelectronics devices.

Gamma-ray shielding features of Co1-xCuxFe2O4 ferrite: A combined experimental, theoretical and simulation investigation

This study describes a rapid synthesis of Co1-xCuxFe2O4 nanoparticles using sol–gel auto-ignition and the produced materials were examined using different techniques such as XRD (X-Ray Diffraction), UV–Vis (Ultraviolet–visible), (FTIR Fourier Transform Infrared Spectroscopy), FE-SEM (Field emission scanning electron microscopy), and EDS (Energy-dispersive X-ray spectroscopy) to explore their structural, optical, and functional group morphological properties, and elemental analysis. Additionally, utilizing several gamma-ray sources and a NaI (Tl) scintillation detector, we studied the gamma-ray shielding characteristics for the prepared materials. Experimental results were validated by the results of XCOM program and the Geant4 simulations. For four chosen ferrites, the gamma ray energy absorption build-up factor is investigated at 0.01–15 MeV incident photon energy and penetration depths of 1–40 mean free path, mfp, using the geometric progression fitting technique. Ferrite samples can be employed as radiation attenuators across a range of nuclear domains, as per the findings of this study. In comparison to the other spinel ferrites, the Co1-xCuxFe2O4 (x = 0.75) ferrite demonstrated superior shielding capabilities. Important details regarding the physio-chemical properties of spinel ferrites and their ability to shield against gamma radiation are provided in the present study.

Rietveld refined structural, elastic, XPS, and dielectric evaluations of Zn-doped Cd–Mg spinel ferrites for high-frequency applications

Sol-gel auto ignition route was utilized to synthesize a series of Zn-doped Cd–Mg spinel ferrites with composition Cd0.5-xMg0.5ZnxFe2O4 (x = 0.0, 0.1, 0.2, and 0.3). All of the prepared nanomaterials that were annealed for 4 h at 900 °C had a cubic structure and were spinel, according to X-ray diffraction studies. The lattice constant decreased as the Zn concentration increased. This is because of the substituent's lower radii. The W–H plot, Size strain plot, and Sherrer Formula were used to calculate the crystallite size, which was in the range of a nanometer. Vibrational spectroscopy studies have also shown that M − O bonds are present in every processed sample and that a spinel cubic structure has formed. Additionally, the cationic distribution and cubic spinel structure were validated by Rietveld refinement of the XRD data. The analysis using X-ray photoelectron spectroscopy (XPS) has confirmed the presence of all metal ions in their respective electronic states. The dielectric characteristics in the 1 MHz-6 GHz range of frequencies were ascertained using an impedance analyzer. Jonscher's power law validated the conduction mechanism in the synthesized ferrite samples. The relaxation time constant calculated from impedance Cole-Cole plots shows that the conduction in all the synthesized nanomaterials was due to the grains rather than the grain boundaries. The minimum reflection loss of −36.54 dB was achieved for Zn-doped Cd–Mg ferrites at x = 0.3. The prepared Zn-doped Cd–Mg spinel ferrites would be an excellent material for high-frequency microwave absorption applications.

Electrocatalytic sensing of metronidazole by R-type hexagonal nanoferrites modified electrode

The current study was aimed to synthesize the R-type hexagonal nanoferrites (SrSn2Fe4O11) for electrochemical sensing of metronidazole (MN) in pharmaceutical and human specimen. The SrSn2Fe4O11 were prepared by sol-gel auto ignition method followed by structural and surface characterization by X-Ray diffraction (XRD) and atomic force microscopy (AFM) respectively. The resulting surface characterization data suggested that the synthesized SrSn2Fe4O11 have a single-phase crystalline structure with a crystalline size of 34.451 nm with surface topographical ranging from 0.506 to 3.37 nm. The SrSn2Fe4O11 modified glassy carbon electrode (SrSn2Fe4O11/GCE) was fabricated by a drop-casting method. The fabricated SrSn2Fe4O11/GCE was successfully applied for detecting MN in a phosphate buffer (PB) at pH-6, followed by a linear voltammetric response with the coefficient of determination (R2 = 0.998). The limit of detection and quantification (LOD/LOQ) for sensing MN was found to be 0.011 to 0.036 μM, respectively. A differential pulse voltammetric study of MN on SrSn2Fe4O11/GCE demonstrated a significant selectivity with RSD 2.0%. The proposed electrochemical method was successfully applied for the quantitative detection of MN in pharmaceutical preparations and biological specimen.

Core-shell structured superparamagnetic Zn-Mg ferrite nanoparticles for magnetic hyperthermia applications

Recently, surface functionalized magentic nanoparticles with core-shell structre were emerged as a promising materials in the biomedical realm. The present work reports the surface-modified Zn-Mg nanoferrite (Zn0.25Mg0.75Fe2O4) with inorganic magnetic core and organic shell coating synthesized by sol-gel auto ignition technique. Standard methods were used to characterise the Zn-Mg Ferrite nanoparticles with surface modifications. The X-ray diffraction (XRD) plot of the present sample verified its nanoscale nature having monophase spinel structure. Oleic acid (OA) was successfully coated over Zn-Mg Ferrite as confirmed by the Fourier Transform Infrared Spectroscopy (FT-IR) with occurrence of vibrational frequency bands associated with cubic spinel formation. By measuring the water contact angle, it was established that Zn-Mg Ferrite had a hydrophilic surface. N2-isotherm measurements were taken in order to gauge the Brunauer–Emmett–Teller (BET) surface area. The superparamagnetic properties of the prepared samples were validated by the magnetization plots. By measuring the Zeta potential and Dynamic Light Scattering (DLS), the colloidal stability and particle size distribution was estimated for the prepared samples. Studies on magnetic hyperthermia were conducted at varied doses (0.5, 2.5, and 5 mg/mL). Cell viability tests were used to examine the biocompatibility of the prepared samples. All of these findings support the use of Zn-Mg nanoferrites coated with OA at a minimal dosage of 2.5 mg/mL in magnetic hyperthermia treatments for non-invasive cancer therapy.

Effect of MgFe2O4 catalyst preparation method on its surface characteristics and Fenton-like oxidation of tartrazine: Statistical comparison and DFT-assisted predation of mechanism

In this study, MgFe2O4 nanoparticles fabricated by co-precipitation (MgF-Cop) and sol-gel auto-ignition (MgF-SG) methods were applied in a Fenton-like process for the degradation of Tartrazine (TA) dye. XRD, FTIR, SEM, and EDX techniques were used to characterize the nanoparticles. Our aim is to compare the relative characteristics of catalysts synthesized by two different methods and to investigate which combinations resulted in better catalytic activity. The interactions between three operating parameters, including catalyst dosage, hydrogen peroxide concentration, and initial TA concentration, were evaluated by employing the Box–Behnken design. The optimal TA removal efficiency D (%) conditions were as follows: catalyst dosage of 0.1 g/L, initial H2O2 dosage of 229 mg/L, and initial TA concentration of 30 mg/L. D (%) achieved on this condition were 79.9% and 98.0% within 60 min for MgF-Cop and MgF-SG, respectively. The co-precipitation method yields a slightly less active catalyst with a lower crystallinity than the sol-gel auto-ignition method. Molecular dynamic (MD) simulations and density functional theory were applied to study the adsorption mechanism and the possible degradation mechanism of TA dye, respectively. The positive total energy calculated indicates that TA has almost no adsorption on the MgFe2O4 nanoparticles. The quantum parameters show that the dye is more reactive and has many sites for HO• radical attack. The Theoretical results correlated with the experimental findings.

Investigation of Dielectric, Magnetic and Electrical Behavior of BFO/GNPs Nano-Composites Synthesized via Sol-Gel Method

Nano composites of Ba0.5Bi0.5Nd0.05Fe0.95O3 multiferroic with graphene nano platelets (GNPs)x (x = 0, 0.125 %, 0.375 %, and 0.5 %) were synthesized using sol-gel auto ignition process. XRD analysis revealed a single rhombohedrally distorted phase of Ba0.5Bi0.5Nd0.05Fe0.95O3. The present study unfold the impact of GNPs on the structural, electrical, dielectric, and magnetic properties of Ba0.5Bi0.5Nd0.05Fe0.95O3 multiferroics. The substitution of Rare earth elements in pure BFO reduced the value of leakage current which is the basic drawback related with pure BFO. The prepared nanocomposites are then sintered at 800 °C for 7 hrs. The X-ray diffraction patterns showed the rhombohedral distorted perovskite crystal structure of the prepared samples including lattice constant, crystallite size, and X-ray density. The average crystallite sizes of the prepared nanocomposites are noticed in the range 28.14 -to 29.74 nm with increasing the GNPs concentration and lattice constant is found in the range 11.59 -to 11.61 Å. Temperature-dependent resistivity is first observed to increase with an increase in temperature then resistivity decreased with increasing the temperature which indicates a semi-conductor-like behavior as measured by two probe I-V characteristics. LCR technique showed that both the dielectric constant and the dissipation factor are decreased with an increase in frequency. VSM results indicated that saturation magnetization is noted to increase while remanent magnetization decreases with increasing concentration of GNPs.

Enhancement of Magnetic and Dielectric Properties of Ni0.25Cu0.25Zn0.50Fe2O4 Magnetic Nanoparticles through Non-Thermal Microwave Plasma Treatment for High-Frequency and Energy Storage Applications.

Spinel ferrites are widely investigated for their widespread applications in high-frequency and energy storage devices. This work focuses on enhancing the magnetic and dielectric properties of Ni0.25Cu0.25Zn0.50 ferrite series through non-thermal microwave plasma exposure under low-pressure conditions. A series of Ni0.25Cu0.25Zn0.50 ferrites was produced using a facile sol–gel auto-ignition approach. The post-synthesis plasma treatment was given in a low-pressure chamber by sustaining oxygen plasma with a microwave source. The structural formation of control and plasma-modified ferrites was investigated through X-ray diffraction analysis, which confirmed the formation of the fcc cubical structure of all samples. The plasma treatment did not affect crystallize size but significantly altered the surface porosity. The surface porosity increased after plasma treatment and average crystallite size was measured as about ~49.13 nm. Morphological studies confirmed changes in surface morphology and reduction in particle size on plasma exposure. The saturation magnetization of plasma-exposed ferrites was roughly 65% higher than the control. The saturation magnetization, remnant magnetization, and coercivity of plasma-exposed ferrites were calculated as 74.46 emu/g, 26.35 emu/g, and 1040 Oe, respectively. Dielectric characteristics revealed a better response of plasma-exposed ferrites to electromagnetic waves than control. These findings suggest that the plasma-exposed ferrites are good candidates for constructing high-frequency devices.

Synthesis and characterization of Ga-doped Ba3MoNbO8.5 electrolytes for intermediate temperature-solid oxide fuel cells

Ba3MoNb1-xGaxO8.5-δ (BMNG, 0 ≤ x ≤ 0.2) powders are successfully prepared by sol-gel autoignition method. The effects of acceptor-type Ga3+ doping on Ba3MoNbO8.5 (BMN) are characterized by thermogravimetric analysis, X-ray diffraction, scanning electron microscope, Raman spectroscopy, and electrochemical impedance spectroscopy. All BMNG samples crystallize as a single phase in the R-3m space group and show great phase stability at various environments. Doping a small amount of gallium can effectively improve bulk conductivity and sintering density of BMN. The ionic conductivity of Ba3MoNb0.9Ga0.1O8.5-δ (BMNG10) is the highest, which can reach 2.05 × 10−2 S cm−1 at 800 °C. The enhanced ionic conductivity is primarily related to the increase of oxygen vacancy concentration and the number of tetrahedral units within the structure. In addition, through successfully assembling and evaluating a single cell supported by the BMNG10 electrolyte, it is proved that the practical utilization of BMNG10 in intermediate temperature-solid oxide fuel cells (IT-SOFCs) is feasible. In short, hexagonal perovskite derivative BMNG10 is a promising oxide ion conductor for IT-SOFCs.

Effect of Fe substitution on the structural, microstructural and dielectric properties of sodium bismuth titanate

Lead free sodium bismuth titanate (NBT) is widely being studied as an emerging room temperature multiferroic and as a ferroelectric material with potential to replace toxic lead based ceramics. Various elements can be substituted in the A-site or B-site to improve its electrical and magnetic properties. In this work, pure and Fe substituted NBT having the chemical formula Na0.5Bi0.5Ti(1-x)FexO3 (x = 0.00, 0.02) were synthesized using sol gel auto ignition method to study the effect of Fe substitution on the properties of NBT. XRD analysis confirmed the rhombohedral symmetry of the synthesized samples and the crystallite size of the samples were calculated using Scherrer’s formula. The morphological property of the samples was studied from the SEM images. UV–Visible Spectroscopy method was employed to study the optical properties of the samples. The dielectric properties of the samples were measured as a function of frequency in the range 100 Hz to 1 MHz at room temperature and also as a function of temperature in the range of 298 K- 473 K using an Agilent HP4284 LCR meter. Usual dispersive behavior of dielectric constant was observed for both the samples at the studied temperature range. Study of frequency and temperature dependence of the AC conductivity suggested that the conduction process in the materials is thermally activated. Jonchers’ universal power law was used to fit the AC conductivity curves to describe the dynamics of charge carrier with suitable conduction mechanism.

Effects of monovalent alkali metals on grain boundary conductivity and electrochemical properties of gadolinia-doped ceria electrolyte

In the present work, 1 mol% alkali metals (Li, Na, K) doped Ce0.9Gd0.1O2-δ (GDC) electrolytes are prepared by citrate-nitrate sol-gel autoignition process. The effects of monovalent alkali metals on the phase structure, micromorphology and grain boundary conductivity of GDC electrolyte are investigated. All Ce0.89Gd0.1A0.01O2-δ (AGDC, A = Li, Na, K) ceramics exhibit a complete fluorite-type structure. SEM results show that all samples sintered at 1400 °C for 5 h have been achieved high densification, and the addition of alkali metals is conducive to the growth of grains. The space charge potential calculated by impedance data has decreased obviously after alkali metals are incorporated into GDC and the value of Ce0.89Gd0.1K0.01O2-δ ceramic is apparently reduced from 0.063 V (GDC) to 0.033 V at 400 °C. These results indicate monovalent alkali metals are beneficial to improve grain boundary conductivity and even total electrical conductivity. Additionally, among all the samples, the Ce0.89Gd0.1K0.01O2-δ electrolyte shows the highest total ionic conductivity of 2.64 × 10−2 S/cm at 700 °C in dry air. The single cell with Ce0.89Gd0.1K0.01O2-δ electrolyte promises the best power density of 624.5 mW cm−2 at working temperature of 700 °C. Therefore, the monovalent alkali metals dopants have promoting effects on improving the grain boundary conductivity, enhancing the sintering activity and output performance of GDC as an electrolyte for IT-SOFCs.

Structural and Magnetic Properties of Nickel Ferrite Nanoparticles Prepared by Solution Combustion Method

Nickel ferrite nanoparticles with chemical formula NiFe2O4 were prepared by standard sol-gel auto ignition technique. Citric acid was used as chelating agent and mixed with solution of nickel nitrate and ferric nitrate in 3:1 proportion to balance the oxidizer to reducer ratio. The obtained particles were sintered at 550°C for 4h to remove the water content, impurity and to obtain better crystallinity. The phase purity and structural formation was confirmed through the analysis of X-ray diffraction technique. The results of X-ray diffraction analysis show the single phase cubic spinel nanocrystalline structure. The particles size calculated from FWHM of the strongest peak (311) is 22 nm in the nanometer dimension. The lattice constant, X-ray density and other structural parameters calculated from XRD data are in good agreement with the literature values. The magnetic measurements were taken at room temperature using hysteresis loop technique. Using M-H plot, the different magnetic parameters such as saturation magnetization, coercivity, remanence magnetization and magneton number were deduced.

Enhanced microwave absorption characteristic of decorated MWCNTs with La0.9Bi0.1Fe0.8Co0.2O3 multiferroic nanoparticles via coating by PEDOT/Polyaniline co-polymer

The microstructural and microwave absorption characteristics of multiferroic nanocomposite (La0.9Bi0.1Fe0.8Co0.2O3 and MWCNTs) coated with PEDOT/Polyaniline co-polymer, was studied systematically. First, MWCNTs/La0.9Bi0.1Fe0.8Co0.2O3 nanocomposite was synthesized using sol-gel auto-ignition and then PEDOT/Polyaniline polymers were coated on MWCNTs/La0.9Bi0.1Fe0.8Co0.2O3 powder via in-situ polymerization method. The effects of the copolymers coating on the structure, morphology, magnetic and electromagnetic performances of the prepared multiferroic nanocomposite surface were comprehensively investigated via XRD, FESEM, VSM and VNA analysis. Enhanced interfacial dielectric relaxation and also perfectly tuned in impedance matching characteristics were achieved by coating nanocomposite with co-polymers. Coating multiferroic nanocomposite with PEDOT/Polyaniline polymers were leading to decrease in matching thickness. Moreover, the significant improvement in microwave absorption properties were also investigated. It was noticed that the coated nanocomposite achieved maximum reflection loss of −60 dB at 11.8 GHz matching frequency with 3.9 GHz bandwidth.

Effect of Cu2+ on structural, elastic and magnetic properties of nanostructured Mn–Zn ferrite prepared by a sol-gel auto-combustion method

The effect of Cu2+ substitution on the structural, elastic and magnetic properties of Mn0·50Zn0.50-xCuxFe2O4 (x = 0.00–0.25 and x changes at a step of 0.05) has been investigated. The compositions were made utilizing the Sol-Gel auto-ignition procedure and the X-ray diffraction (XRD) analysis confirmed the purity of the phase. Decreasing trends have been observed in the lattice constant, bulk density and Poisson's ratio but average grain size, theoretical density and porosity increases with the increasing concentration of Cu2+. Nano metric crystallite sizes have been estimated from FWHM of the X-ray diffraction peaks. Cation distribution in the present study was assessed by the XRD data. Site occupancy of cations helps to understand the variation in magnetic properties and also explains the change taking place in saturation induction, remanence induction and coercivity. The initial permeability increases with the increasing Cu2+ concentration up to x = 0.20 and above this x value it decreases. Observed variations of initial permeability have been clarified based on the increment of average grain size, which also has been conformed from optical micrographs. Saturation induction, coercivity, remanance, and squareness ratio have been considered as a component of Cu2+ content from theB−H loops of the compositions. Possible explanations for the perceived structural, elastic and magnetic behavior with Cu2+ substitutions are discussed.

Effects of calcination temperature and time on the Ca3Co4O9 purity when synthesized using starch-assisted sol-gel combustion method

Ca3Co4O9 is a p-type semiconducting material that is well-known for its thermoelectric (TE), magnetic, electronic, and electro-optic properties. In this study, sol-gel autoignition was used to prepare Ca3Co4O9 at different calcination temperatures (773, 873, 973, and 1073 K) and time (4, 6, 8, 10, 12, and 14 h) using starch as a fuel. The phase and microstructure of the prepared Ca3Co4O9 powder were investigated. Thermogravimetry.differential thermal analysis (TGA) confirms that the final weight loss occurred at 1073 K to form Ca3Co4O9 stable powder. The variable-pressure scanning electron microscopy (VP-SEM) images show that the size of powder particles increases from 1.15 to 1.47 μm as calcination time increases from 4 to 12 h, and the size remains almost constant thereafter. A similar pattern is also observed on the increment of the crystallite size and percentage of crystallinity with X-ray diffraction (XRD) analysis. The highest crystallinity is found about 92.9% when the powder was calcinated at 1073 K for 12 and 14 h with 458 and 460 Å crystallite size, respectively. Energy dispersive X-ray spectroscopy (EDS) analysis demonstrates that the calcinated powder has a high intensity of Ca, Co, and O with uniform distribution. High-resolution transmission electron microscopy (HRTEM) images prove that there is no distinct lattice distortion defect on the crystal structure.

The role of La3+ substitution in modification of the magnetic and dielectric properties of the nanocrystalline Co-Zn ferrites

Co-Zn spinel ferrites with lanthanum (La3+) ion substitutions having formula Co0.7Zn0.3LaxFe2-xO4 (x = 0.0, 0.025, 0.05, 0.075, 0.1) were prepared using sol gel auto ignition route. The structural characterization of the ferrites was performed by the x-ray diffraction (XRD) method. The parameters calculated from the XRD analysis include lattice parameter, density, porosity, crystal size and lattice strain. The nanocrystallinity of the ferrite samples was observed with the crystallites of 20–30 nm size. The scanning electron microscopy (SEM) was employed to analyse the morphology of the ferrite crystals. The size and shape of the ferrite nanocrystals were confirmed from transmission electron microscopy (TEM) images. The crystal planes revealed from XRD calculations were confirmed by the selected area electron diffraction (SAED) analysis of the ferrites. Vibrating sample magnetometer (VSM) measurements of the ferrite samples were performed to study the magnetic properties of the ferrites. The effects of the La3+ substitution were observed on the coercivity and saturation magnetization of the ferrites. The variation of dielectric properties of the ferrites within 50 Hz to 5 MHz frequency band were studied at room temperature. The dielectric relaxation in the ferrites was governed by the electron hopping between divalent (Fe2+ and Co2+) and trivalent (Fe3+ and Co3+) cations. Remarkable impact of La3+ composition and the crystal size was observed on dielectric constant as well as loss tangent.

Spinel zinc ferrite nanoparticles: an active nanocatalyst for microwave irradiated solvent free synthesis of chalcones

A profoundly effective magnetically recoverable nano zinc ferrite nanocatalyst was fabricated by means of sol-gel auto ignition strategy. The synthesized nanocatalyst has been completely portrayed by standard techniques for structural, morphological, compositional, surface, magnetic, dielectric, optical and photoluminescence properties individually. The x-ray diffraction pattern affirmed the arrangement of cubic spinel structure with an average crystallite size of 21 nm. FE-SEM images uncovered the circular morphology with nanometric average grain measure (37 nm). The surface area, pore volume and pore radius was observed to be 39.812 m2 g−1, 3.41 cc g−1 and 1.34 nm individually from BET analysis. VSM investigation demonstrated the superparamgnetic nature of the prepared sample with moderate magnetization value and negligible coercivity. The optical band gap deduced from UV–vis spectra was observed to be 2.098 eV. Every one of these properties of zinc nanoferrite makes them brilliant contender for microwave radiation absorption. Further, a proficient and versatile microwave irradiated solvent free synthesis of chalcone derivatives has been developed using prepared zinc nanoferrite catalyst. The remarkable highlights of this new protocol are solvent free reaction, economical cheapness, eco-friendliness, high yields, reduced reaction times and easy recovery and reuse of zinc ferrite nanocatalyst.

Sol gel derived MnTi doped Co2 W-type hexagonal ferrites: Structural, physical, spectral and magnetic evaluations

W-type BaSr Co2 hexaferrites doped with Mn and Ti of the following composition Ba0.5Sr0.5Co2MnxTixFe16-2xO27 (x = 0.00, 0.50, 1.00, 1.50, 2.00, 2.50) were synthesized by sol-gel auto ignition method. The structure, phase, spectral bands, microstructure, and magnetic behaviors of the MnTi doped BaSr Co2 W-type ferrites were determined using XRD, FTIR, FESEM, and VSM respectively. Structural and physical parameters such as lattice parameters ‘a’ and ‘c’, crystallite size, cell volume, micro strain, porosity, bulk and X-ray density of the MnTi doped BaSr Co2 W-type hexaferrites were evaluated. The detailed and refined structural properties were determined using the Rietveld refinement of the MnTi doped BaSr Co2 W-type hexagonal ferrites. MAUD software was used for the refinement of the MnTi doped BaSr Co2 W-type hexagonal ferrites patterns. Rb, Rwp and Rexp values were found in the range of 10–19 for MnTi doped BaSr Co2 W-type hexagonal ferrites. The force constants at respective sites were also investigated through FTIR studies. FESEM images showed the hexagonal shape of the MnTi doped hexaferrites. Magnetic properties were estimated from the hysteresis loops recorded by VSM. The magnetic properties were decreased with the MnTi doping. However, anisotropic field was also found to be decreased with MnTi doping. This might be due to the ionic radii and nonmagnetic substitution of Ti in BaSr Co2 W-type hexagonal ferrites. The low coercivity values of these ferrites suggest the use of MnTi doped BaSr Co2 W-type ferrites for microwave absorption, memory devices and magnetic radar absorbing materials (MRAMs) in high frequency regime.

Impact of Co doping on physical, structural, microstructural and magnetic features of MgZn nanoferrites for high frequency applications

Cobalt (Co) doped MgZn spinel nanoferrites with composition Mg0.5Zn0.5Cox Fe2-xO4 at x = 0.0, 0.10, 0.20, 0.30, 0.40, 0.50 were prepared using sol-gel auto ignition method. The characterizations techniques such as FESEM, FTIR, XRD and VSM were used to determine the morphology, force constants, phase, structure and magnetic features of the samples. Lattice parameters, FWHM, d-spacing, crystallite size, micro strains and volume were investigated using high score plus software. Materials analysis using diffraction (MAUD) software was also used to study the Rietveld refinement properties of the Co doped MgZn ferrites. Physical properties such as porosity, X-ray and bulk density were also determined. Force constants of their respective absorption bands were calculated from FTIR of the Co doped MgZn nanoferrites. Single phase structure with cubic phase were observed for MgZn and Co doped MgZn at x = 0.0 whereas second phase was observed at higher Co concentrations respectively. FESEM show regular shape of the particles at low Co concentrations whereas agglomerations were observed at higher Co concentrations respectively. The magnetic properties of the Co doped MgZn ferrites were also investigated from VSM study. Magnetic remanence, coercivity, initial permeability, saturation magnetization, Bohr magneton and anisotropy constant were determined from VSM analysis. The coercivity, saturation magnetization, remanence, anisotropy constant and initial permeability were enhanced with the doping of ‘Co’ in MgZn nanoferrites. Response of the Co doped MgZn nanoferrites at high frequency regime was also evaluated. It can be seen that the response from all the Co doped MgZn nanoferrites was 2.84 GHz–5.96 GHz respectively and suggested the use of these nanoferrites for the operation of nanodevices in the X-band high frequency regime.

Impact of indium substitution on dielectric and magnetic properties of Cu0.5Ni0.5Fe2-xO4 ferrite materials

Indium substituted CuNi nanoferrites with nominal compositions Cu0.5Ni0.5InxFe2-xO4 (x = 0.00–0.32) were successfully synthesized by sol-gel auto ignition method. X-ray diffraction patterns illustrated the single phase spinel structure for x ≤ 0.24. The lattice parameter ‘a’ increased from 8.3349 to 8.3723 Å and then it decreased for x = 0.32. X-ray density increased from 5.43 to 5.79 g/cm3. The average crystallite sizes lie in the range 33.21–17.78 nm. The cell volume was increased from 579.03 to 586.86 Å3 with the substitution of indium ions into the spinel lattice of copper nickel ferrites. The compositional dependence of tetrahedral and octahedral radii was explained on the basis of lattice parameter. The incorporation of In3+ ions in copper nickel ferrites exhibited the decreased in bulk density. The dielectric parameters were explained over entire range of frequency (1M-3 GHz). The dielectric parameters i.e dielectric constant, dielectric loss and tan loss were found to decrease with the increase of indium concentration. The saturation magnetization (Ms) and Bohr magneton (nB) first increased and then decreased. The remanence (MR) was increased with the substitution of indium ions. The coercivity and anisotropy constant were decreased which might be due to weak A-B super exchange interaction. The results of magnetic and dielectric properties suggested that In3+ substituted copper nickel ferries are suitable for high frequency applications.