Formation Of Spinel Structure Research Articles

Green synthesis of cobalt ferrite and Mn doped cobalt ferrite nanoparticles: Anticancer, antidiabetic and antibacterial studies

CoFe2O4 are important magnetic NPs with high coercivity and moderate magnetization.These properties of CoFe2O4 NPs show variation when doped with various metals. Recent studies explained that Cobalt ferrites doped with metal ion like Mn+2, have attracted increasing attention in many applications, particularly in biomedical applications. A relatively simple way is employing plants and their extracts as precursors instead of toxic chemicals to produce NPs with desirable characteristic. In current study we report green synthesis and characterization of magnetic (CoFe2O4, MnCoFe2O4, CoFe2O4@S.C, MnCoFe2O4@S.C) nanoparticles using ethanolic extract of Swertia Chirata. To enhance application as biocompatible magnetic nano drug delivery vector and cell targeting efficacy of drugs, Glimepiride (GLM), Dexamethasone (DXM), Fexofenadine (FEX) and Levofloxacin (LVX) 1were loaded on synthesized NPs.Synthesized CFNPs has been broadly characterized and applied for in vitro anticancer, antidiabetic and antibacterial potential. For synthesis of CoFe2O4 (CF), CoMnFe2O4 (CFM), CoFe2O4@S.C (SCF) & CoMnFe2O4 @S.C (SCFM), stochiometric amounts 5mmol of CoCl2·6H2O (0.284g) and 10mmol FeCl3·6H2O (0.378g) were dissolved in 13mL of deionized water. To this sodium acetate (3.05g) and urea (0.6g) were added until complete dissolution. Afterward n-heptane was added, and contents were then transferred to Teflon lining autoclave at 180°C for 4h. Black powder CoFe2O4 NPs after washing, were dried and calcined at 450oC for 2h. XRD diffractogram of CF have proved the single-phase cubic spinel structure formation for all samples. Swertia Chirata formulations were shown to have effective in vitro antidiabetic activity. CF, CFM & SCFM showed good inhibition of α-glucosidase with very low concentration 6µg/mL, 5µg/mL and 4µg/mL as compare to 12.41µg/mL of acarbose. SCF showed that the value slightly higher than 16µg/mL compared to standard. Drug loaded CFNPs (L-CFNPs, F-CFNPs, D-CFNPs & G-CFNPs) also effectively inhibited α-glucosidase. IC50 value for CFNPs inhibition of α-glucosidase was 12.4µg/mL.All synthesized CF NPs showed cytotoxic potential against breast cancer cells MCF-7. About 50-60% cell viability and cytotoxicity 40% were observed for bare CFNPs as compare to Doxorubicin with related toxicity 80% and 20% cell viability.Among synthesized samples almost all samples without conjugation of any drug showed activities against at least one bacterial strain. CFM, SCF, SCFM were active against S. aureus at concentration 100µg/mL, 100µg/mL, and 50µg/mL respectively. The synthesized CF NPs showed significant cytotoxic potential against MCF-7 breast cancer cell line. Further, drug loaded samples displayed lesser cell viability and slightly increased cytotoxicity in range of 40-50% in comparison with bare CFNPs. However, higher toxicity was observed for CFMGS towards MCF-7 cells with results nearly equal to Doxorubicin with significant decrease in viability.CF, CFM & SCFM showed good inhibition of α-glucosidase with very low concentration 6µg/mL, 5µg/mL and 4µg/mL as compare to 12.41µg/mL of acarbose.Among synthesized samples almost all samples without conjugation of any drug showed activities against at least one bacterial strain.

Investigation of Cr3+ doped Zn-Co nanoferrites as potential candidate for self-regulated magnetic hyperthermia applications

Controlling the Curie temperature (TC) in the range from 42 °C–46 °C in magnetic hyperthermia (MH) therapy is an essential research topic because overheating can cause irreversible damage to healthy tissue. When TC is in the above temperature range, the magnetic nanoparticles reach a paramagnetic state, effectively turning off the MH treatment. In this work, we synthesized Zn-Co nanoparticles of representative composition Zn0.54Co0.46CrxFe2-xO4, where the Fe3+ cations are carefully replaced by Cr3+ ions, which allow a precise tuning of TC and hence the self-regulation of MH. The x-ray diffraction analysis of the prepared nanoparticles confirms the formation of a single-phase cubic spinel structure. The average crystallite of the nanoparticles increases with Cr3+ doping, while the Tc and saturation magnetization decrease considerably from 78 °C (x = 0.1) to 27 °C (x = 0.6) and 46.6 emu g−1 (x = 0.1) to 15.3 emu g−1 (x = 0.6), respectively. Besides MH potential of the investigated samples as revealed from specific absorption rate (SAR) assays and the maximum temperature reach (Tmax), vary from 7 W g−1 and 37.3 °C, for x = 0.6, to 38 W g−1 and 62.9 °C, for x = 0.1, we found that the composition Zn0.54Co0.46Cr0.4Fe1.6O4 is more promising with SAR of 22 W g−1 and Tmax = 42.3 °C, which is precisely lies in the safe temperature range to automatically activate the self-regulation during the magnetic hyperthermia treatment. The results reveal an excellent combination between size distribution and Cr3+ content in Zn-Co-based ferrite, which has a great potential for self-regulated magnetic hyperthermia applications.

Synthesis and investigation of structural, elastic, and electrical properties of cobalt and magnesium substituted Ni–Zn spinel ferrite nanoparticles

The sol–gel auto-combustion approach was used to create Ni0.4M0.2Zn0.4Fe2O4 (M = Ni2+, Mg2+, and Co2+) nanoparticles. X-ray diffraction (XRD), Fourier transform infrared spectroscopy, energy dispersive x-ray spectroscopy (EDS), and an inductance–capacitance–resistance (LCR) meter were used to analyse the samples’ structural, elastic, and electrical properties. In all samples, the XRD patterns obtained indicated the formation of a monophasic cubic spinel structure with no identifiable impurity phase, which was supported by EDS investigations. The introduction of substituting ions, specifically Mg2+ and Co2+, into Ni–Zn ferrite nanoparticles results in an increase in the lattice parameter. The lattice parameter for Ni–Zn is 8.377 Å, while for the substituted nanoparticles it is 8.389 and 8.388 Å for Mg2+ and Co2+ respectively. Additionally, the crystallite size of the substituted nanoparticles increases to 46.57 nm from 40.75 nm for Ni–Zn. However, the x-ray density of the substituted nanoparticles decreases to 5.180 and 5.337 g cm−3 for Mg2+ and Co2+ respectively, from 5.358 g cm−3 for Ni–Zn. The elastic parameters, such as the Young’s modulus, Debye temperature, bulk modulus, and rigidity modulus, were calculated. The good elastic characteristics of Ni–Zn ferrite were confirmed and may be explained by the lower lattice parameter values and smaller crystallite sizes. Temperature and frequency effects on dielectric behaviour and AC electrical conductivity (σ AC) were investigated. At ambient temperature, the dielectric characteristics, specifically the dielectric constant (ϵ′) and loss tangent (tanδ), were computed over a frequency range of 100–2 MHz. The compositions display normal dielectric properties, which are attributed to the interfacial polarisation following the Maxwell–Wagner model. The AC conductivity of nanoparticles was shown to decrease when Mg2+ and Co2+ were substituted into Ni–Zn ferrite. Furthermore, the AC conductivity diminishes with decreasing frequency, which is a sign of ionic conductivity. There was a direct relationship between the temperature and the values of ϵ′, tanδ, and σ AC for different ions.

Feasibility of superparamagnetic NiFe2O4 and GO-NiFe2O4 nanoparticles for magnetic hyperthermia

Superparamagnetic Ni-ferrite and their composite with graphene oxide nanoparticles are synthesized using simple hydrothermal method. The morphology and the crystal structure measurements show formation of spinel structure with cubic/octahedral shape nanoparticles with average particles size of 16.63 nm and 12.87 nm for NiFe2O4 and GO-NiFe2O4 respectively. The magnetic properties show superparamagnetic behavior at room temperature with saturation magnetization of 50 and 35 emu/g and Coercivity of 35 and 25 Oe for NiFe2O4 and GO-NiFe2O4 respectively. The zero-field cooling and field cooling magnetization dependence on temperature measurements yield blocking temperature of 315 and 257 K for NiFe2O4 and GO-NiFe2O4 respectively. Those values confirm the superparamagnetic behavior of the samples. Moreover, the blocking temperature of the NiFe2O4 is within the therapeutic temperature range of magnetic hyperthermia therapy. The feasibility of hyperthermia reveals heating power of 165 and 15 W/g for NiFe2O4 and GO-NiFe2O4 respectively, which is comparable and even much better than the previous published work by others. Therefore, the findings open new route for the potential of NiFe2O4 and GO-NiFe2O4 nanoparticles for hyperthermia and to be tested for in vitro/ in vivo hyperthermia in the future.

Carbonaceous MnFe2O4 nano-adsorbent: Synthesis, characterisation and investigations on chromium (VI) ions removal efficiency from aqueous solution

Carbonaceous manganese ferrite nanoparticles were prepared at relatively lower temperature using co-precipitation method followed by a single-step pyrolysis process. Synthesized nanoparticles were further characterized by different spectroscopic and microscopic techniques. The X-ray Diffraction (XRD) study confirmed the formation of single phase cubic spinel structure and the presence of graphitic carbon of plane (002) and the size of the prepared nanostructure was of 36 nm. With the confirmation of formation of carbonaceous MnFe2O4 and the number of oxygen functionalities such as hydroxyl and C-O-C groups emanating from the carbon matrix, as confirmed by the Fourier Transform Infrared (FT-IR) studies motivated their usage to remove Cr (VI) ions from aqueous solution. The study parameters such as influence of time, adsorbent dosage, concentration and pH are explored along with isotherm and kinetic studies. The carbonaceous nanoparticle was able to remove Cr (VI) by ∼80% at native pH, with a carbonaceous MnFe2O4 dose of 10 mg, and the initial concentration 10 ppm of contaminant with the contact time, 80 min and is found promising for the practical applications.

Structural, magnetic, and antibacterial activity of the pure, Zn-doped, and Zn-doped/sugar-assisted coprecipitation synthesized semicrystalline Co3O4 compound

Undoped, Zn-doped, and Zn-doped/sugar-assisted semi-crystalline structures of Co3O4 were made by introducing a facile precipitation approach. The synthesized compounds were tested for surface characteristics, magnetic properties, and antibacterial activity. Powder X-ray diffraction (XRD) analysis confirmed semi-crystalline behavior and spinel structure formation in all synthesized compounds. Using scanning electron microscopy (SEM) characterization, microstructure formation along with the large agglomeration of spherical particles, uniform distribution of spherical particles, and spherical-flake-like particle structures were noticed for the pure, Zn-doped, and Zn-doped/sugar-assisted Co3O4 samples, respectively. From the vibration sample magnetometry (VSM), Zn-doped/sugar-assisted Co3O4 was found to have relatively lower saturation magnetization when compared to pure Co3O4 and Zn-doped Co3O4 material. The antibacterial performance of the synthesized compounds against the bacteria Escherichia coli (E.coli) and Staphylococcus aureus (S. aureus) has been tested. The above-mentioned germicidal responses showed a relatively larger inhibition zone for the Zn-doped and Zn-doped/sugar-assisted Co3O4 compared to the undoped Co3O4 sample. The obtained diameter inhibition zone values of all synthesised compounds are comparable to the standard positive and negative control.

Ni-doped Mg-Zn nano-ferrites: Fabrication, characterization, and visible-light-driven photocatalytic degradation of model textile dyes

Novel Ni2+-doped NixMg0.5Zn0.5-xFe2O4 [x = 0.0 to 0.5] nano-ferrites have been successfully prepared by the facile co-precipitation method. The XRD data demonstrated the formation of a single-phase cubic spinel structure. The optical band gap of the synthesized samples was found to increase with increasing Ni2+ content from 1.72 eV (x = 0.1) to 1.82 eV (x = 0.5). Samples with Ni2+ doping exhibit a transition from superparamagnetic to soft ferromagnetic activity. Ni0.5Mg0.5Fe2O4 catalyst has been found to have enhanced degrading efficiencies of 95.92 and 90.21% against methylene blue and xylenol orange in visible light, respectively. The main reactive species, as determined by scavenging activity, were hydroxyl radicals.

Effect on magnetic behaviour of Ag and Cd doped cobalt ferrite nanoparticles prepared by glycine-assisted sol-gel auto combustion method

The nanocomposites of the Silver (Ag) and cadmium (Cd) based, cobalt ferrite having formula AgxCdxCo1–2xFe2O4 (where x = 0.0, 0.05, and 0.1) have been successfully prepared by glycine-assisted Sol-gel derived auto combustion technique. The synthesized samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), UV–visible spectrum, and Vibrating Sample Magnetometer (VSM). The XRD and FTIR results reveal the formation of a single-phase cubic spinel structure with crystallite sizes 14–19 nm. SEM analysis of surface morphology revealed spherical and cubic-shaped nano-particles. FTIR spectra indicated two fundamental absorption peaks around 580 cm-1 and 460 cm−1. This confirmed the existence of m-o bonding in the synthesized products corresponding to the stretching vibration of tetrahedral (A) and octahedral (B) lattice sites. According to UV-Visible analysis, it is observed that the optical band gap energies vary from 1.88 eV to 1.52 eV as the Ag/Cd concentration increased. From VSM data, the magnetic behavior of prepared specimens is studied and the corresponding variations in the (Ms), (Hc), (Mr), and Mr/Ms values are analyzed. This prepared composites materials are recommended for magnetic storage applications.

Structural and optical properties of gadolinium doped-magnetite nano-crystal for photocatalytic application

Doped ferrite materials offer a combination of enhanced magnetic properties, multifunctionality, higher Curie temperature, biocompatibility, and potential energy applications. Their unique characteristics make them appealing for research in diverse fields, including materials science, electronics, biomedical engineering, and energy technology. In present work, Gadolinium-doped magnetite samples are synthesized following the co-precipitation method. The effects of doping on the structural and optical properties of Fe3O4 are studied. Structural parameters of the samples such as cell parameters, cell volume crystalline size, x-ray density, and average micro-strain are calculated from the analysis of x-ray diffraction (XRD) data via Rietveld refinement method. An increase in crystalline size and cell volume is observed while a reduction in micro-strain is observed with increase in doping concentration. The particle size estimated from FE-SEM data ranges from 9 to 16 nm and is in good agreement with XRD data and confirms the formation of nanoscopic phase of the particles. The presence of characteristic peaks concerned with tetrahedral and octahedral site vibrations in the Fourier transform infrared spectroscopy data approve the formation of inverse spinel structure. The distribution of Gd in the samples is determined with Energy dispersive x-ray analysis. The optical studies show that the direct and indirect band gaps decrease from 4.07 to 3.95 eV and 3.79–3.65 eV, respectively. These values of band gap are indicated the potential use of the synthesized nanoparticles for photocatalytic application.

Complex dielectric-impedance spectroscopic studies of magnetite added chitin biopolymer

We have successfully synthesized magnetic chitin (MCH) by incorporating iron oxide nanoparticles into biodegradable and abundantly naturally available chitin by the coprecipitation method. X-ray diffraction (XRD) characterization revealed formation of cubic inverse spinel structure of Fe3O4 nanoparticles. In addition to this, other characterization studies like energy dispersive X-ray analysis (EDX) and vibrating sample magnetometry (VSM) were also performed to have an insight into the compositional and functional nature of the structure. A detailed spectroscopic study of complex impedance and dielectric constant for a wide frequency range of ~1 Hz to 10 MHz at discrete temperatures ~300–400 K has been performed by us for the first time on MCH in order to understand various relaxation processes. From permittivity, we have estimated the height of the potential barrier to be ~95.8 ± 0.3 meV. Impedance measurements yielded an activation energy of ~35.85 meV. Thermogravimetric analysis (TGA) of the sample showed exceptionally high thermal stability of the sample with percentage of residual mass at 800 ℃ being ~73% in MCH, which is quite high in comparison to the pristine chitin. An S shaped curve obtained through VSM measurement confirmed the superparamagnetic nature of the nanocomposite. The study assumes significance in the present scenario of rising awareness about the environment and demand to explore alternative green materials with numerous biomedical/environmental applications ranging from drug delivery vehicles in COVID-19 treatment to food packaging.

Structural, Frequency and Temperature Dependent Dielectric Properties of Zn2+ Substituted Ni-Co Based Spinel Ferrite (ZnxNi0.8−xCo0.2Fe2O4)

Zinc substituted nickel-cobalt ferrites, i.e., ZnxNi0.8−xCo0.2Fe2O4 (x = 0.0, 0.05, 0.10 and 0.20) with average crystallite size 100 nm were synthesized by citrate-gel auto-combustion method to investigate effects of Zn2+ substitution on the structural and dielectric properties. Both X-ray diffraction (XRD) and IR spectroscopy studies confirms the formation of pure cubic spinel structure. Variation of lattice parameter infers Vegard’s law linear dependence with the addition of Zn2+ concentration. The temperature-dependent behavior of dielectric and modulus spectra has been studied within the frequency range 100 Hz-100 kHz for different temperatures between 100 K and 400 K. It was concluded that the dielectric responses of ZnxNi0.8−xCo0.2Fe2O4 are found to be frequency dependent and thermally activated. Also, In the Zn doped ferrites variations of dielectric loss (tan δ) and the imaginary part of electric modulus (M") show the presence of the non-Debye type of dielectric relaxation. Rise in Zinc concentration leads to a decrease in dielectric constant (ε r) due to the declining of Fe3+–O–M2+ conducting network (M is Co or Ni). Here, we report a low loss tangent factor of the order of for the sample Ni0.6Zn0.2Co0.2Fe2O4 make this composition suitable for high frequency-applications at room temperature. The activation energy is calculated from electric modulus formalism and DC electrical conductivity and found to increase with further substitution of Zn2+ concentration.

Enhanced Electrochemical Performance of Rare-Earth Metal-Ion-Doped Nanocrystalline Li4Ti5O12Electrodes in High-Power Li-Ion Batteries

A comprehensive and comparative exploration research performed, aiming to elucidate the fundamental mechanisms of rare-earth (RE) metal-ion doping into Li4Ti5O12 (LTO), reveals the enhanced electrochemical performance of the nanocrystalline RE-LTO electrodes in high-power Li-ion batteries. Pristi ne Li4Ti5O12 (LTO) and rare-earth metal-doped Li4-x/3Ti5-2x/3LnxO12 (RE-LTO with RE = Dy, Ce, Nd, Sm, and Eu; x ≈ 0.1) nanocrystalline anode materials were synthesized using a simple mechanochemical method and subsequent calcination at 850 °C. The X-ray diffraction (XRD) patterns of pristine and RE-LTO samples exhibit predominant (111) orientation along with other characteristic peaks corresponding to cubic spinel lattice. No evidence of RE-doping-induced changes was seen in the crystal structure and phase. The average crystallite size for pristine and RE-LTO samples varies in the range of 50-40 nm, confirming the formation of nanoscale crystalline materials and revealing the good efficiency of the ball-milling-assisted process adopted to synthesize nanoscale particles. Raman spectroscopic analyses of the chemical bonding indicate and further validate the phase structural quality in addition to corroborating with XRD data for the cubic spinel structure formation. Transmission electron microscopy (TEM) reveals that both pristine and RE-LTO particles have a similar cubic shape, but RE-LTO particles are better interconnected, which provide a high specific surface area for enhanced Li+-ion storage. The detailed electrochemical characterization confirms that the RE-LTO electrodes constitute promising anode materials for high-power Li-ion batteries. The RE-LTO electrodes deliver better discharge capacities (in the range of 172-198 mAh g-1 at 1C rate) than virgin LTO (168 mAh g-1). Among them, Eu-LTO provides the best discharge capacity of 198 mAh g-1 at a 1C rate. When cycled at a high current rate of 50C, all RE-LTO electrodes show nearly 70% of their initial discharge capacities, resulting in higher rate capability than virgin LTO (63%). The results discussed in this work unfold the fundamental mechanisms of RE doping into LTO and demonstrate the enhanced electrochemical performance derived via chemical composition tailoring in RE-LTO compounds for application in high-power Li-ion batteries.

Highly Improved Acetone Gas Sensing Performance of Mesoporous Cobaltosic Oxide Nanoparticles and Physical Mechanism

Mesoporous Cobaltosic oxide nanoparticles are now widely employed in a variety of applications across the world. It is both environmentally and economically favorable. It was well prepared in this study using a cost-effective thermal stirring procedure. The X-ray diffraction method at ambient temperature was used to explain the formation of single spinel structure, purity, and cat-ion distribution of the material, and the lattice constant of mesoporous Cobaltosic oxide nanoparticles was 8.23 Å. SEM and EDX examination were used to investigate phase formation, elemental content, and surface morphology. The average particle size for primitive mesoporous Cobaltosic oxide nanoparticles is 17nm. DRS determined the band gap for mesoporous Cobaltosic oxide nanoparticles to be 1.48 eV for direct band bending and 2.19 eV for indirect band gap. The sensitivities of the sample are greater due to the mesoporous-structures with a large surface area. Mesoporous Cobaltosic oxide nanoparticles have a greater specific surface area (59.63m2 g− 1), resulting in good acetone gas sensing characteristics at the optimal working temperature of 150°C. Furthermore, the sample exhibits high stability and selectivity against acetone gas. The gas-sensing mechanism is determined by comparing the sensitivity of Mesoporous Cobaltosic oxide nanoparticles to surface oxygen and acetone gas adsorption. It is the best among the top other materials, according to the results.

Synthesis and characterization of nanoparticles of cobalt and nickel ferrites for elimination of hazardous organic dyes from industrial wastewater.

This study presents the results of synthesis and characterization of nanoparticles of cobalt ferrite (CoFe2O4) and nickel ferrite (NiFe2O4) using co-precipitation method followed by application for removal of hazardous organic textile dyes of thiazole yellow G (TYG) and alizarin yellow R (AYR). XRD analysis confirmed formation of cubic spinel structure with average crystallite sizes at 16.07nm and 13.84nm for CoFe2O4 and NiFe2O4, respectively. Field emission scanning electron microscopy (FESEM) analysis showed agglomeration of spherical shape morphology with uniformly distributed Co, Ni, Fe, and O elements. The surface area calculated from Brunauer-Emmett-Teller (BET) analysis was 64 m2/g and 62 m2/g for CoFe2O4 and NiFe2O4, respectively. Vibrating sample magnetometer (VSM) showed super-paramagnetic behavior for all samples with magnetic saturation (Ms) at 7.269 and 6.61emu/g for CoFe2O4 and NiFe2O4, respectively. The adsorption influencing parameters such as pH of solution, quantity of adsorbent, and contact time on dye removal efficiency were thoroughly investigated. Overall, acidic condition of samples with pH at 4 favored the maximum removal efficiency by CoFe2O4 as 98, 97, and 93%, and by NiFe2O4 as 96, 93, and 92%, respectively, for TYG, AYR, and mixture sample. The Langmuir adsorption isotherm model describes the equilibrium of all samples with the best fit of coefficient of determination (R2). The adsorption results fitted well with a pseudo-second-order kinetic model for all samples. The regeneration-reuse ability of adsorbents and cost estimation analysis of the dye removal process suggested that the economic suitability of nano-adsorbents for remediation of textile effluents was favored. The estimated thermodynamic parameters inferred that the removal of organic dyes onto the surface of CoFe2O4 and NiFe2O4 is a spontaneous, favorable, and exothermic physical adsorption process.

The effect of Cadmium Substitution on the structural and magnetic properties of Nickel Ferrite

Nickel – Cadmium ferrites having the chemical formula (Ni1-xCdxFe2O4), (0 ≤ X ≤ 0.5) were prepared by using powders technology method. The particle size of the ferrite samples were estimated from X-ray diffraction studies after the confirmation of the formation of single phase spinel structure of the ferrites. We found that the Lattice constant and density (ρx-ray) increased with Cd content while the porosity was noticed to decrease. Also the magnetic testing showed decreases in values the Coercive Force from (0.408 KA/m) to (0.384 KA/m) and the Remnant Magnetization from (0.056 Tesla) to ( 0.048 Tesla) and the Magnetic Relative permeability is the within range (0.137 ~ 0.125) with increasing of the Cadmium concentration while the Magnetic Susceptibility was noticed to increase from (0.862) to (0.875).

Influence of cobalt on magnetic, dielectric and electrochemical properties of copper ferrite nanoparticles via hydrothermal method

Nanoparticles of undoped and cobalt doped copper ferrite (CoxCu1-xFe2O4) were synthesized by hydrothermal method. The results of XRD had confirmed the formation of single phase cubic spinel structure and the crystallite size was decreased from 41 to 30nmwith increasing dopant (Co) content. FT-IR spectra exhibited the two promising absorption bands which corresponded to intrinsic stretching vibrations of metals with oxygenat 454 and 573 cm−1 intetrahedral(A) and octahedral(B) sites, respectively. FESEM and HRTEM revealed the agglomeration of spherical particles which existed within the nanorange. The DLS and Zeta potential measurements found the stability of the nanoparticles with good conductive nature. UV-DRS revealed the decrease in bandgap with decrease in the crystallite size due to defect levels. XPS revealed the chemical states of metallic species like Cu2+,Fe3+ and Co2+. The dielectric study revealed the increase of AC conductivity with the increase infrequency. Magnetic parameters like, Ms, Mr, Hc and K were obtained from magnetic hysteresis looprevealed ferromagnetic and pseudo-single domain nature of the nanoparticles. The electrochemical properties studied by cyclic voltammetry confirmed the pseudocapacitive behaviour with high specific capacitance at a low scan rate for the electrode material.

Effect of Li substitution on the structural, magnetic, and electrical properties of nanocrystalline LixNi0.6-2xZn0.4Fe2+xO4

Nanocrystalline LixNi0.6–2xZn0.4Fe2+xO4 (where x = 0.00, 0.05, 0.10, 0.15, and 0.20) were prepared by the auto-combustion synthesis route. Each composition was sintered at different sintering temperatures, Ts, (1100–1250 °C) for 5 h. The optimum Ts for each composition was selected based on their maximum bulk density. For the first three compositions (x = 0.00, 0.05, and 0.10), the optimum Ts was 1200 °C, and for x = 0.15, Ts = 1175 °C, and for x = 0.20 Ts = 1150 °C. The Rietveld refinement of X-ray diffraction (XRD) patterns confirmed the monophasic formation of cubic spinel structure. The lattice constant was found to decrease (8.3821–8.3706 Å) slightly, complying with Vegard's law. The crystallite size calculated using Scherrer formula varied from 53 to 59 nm. However, the microstructural study showed that the average grain size has enlarged (0.53–1.39 μm) with substituting Li content up to x = 0.10. The real part of initial permeability increased up to x = 0.10, and the maximum value was 52 (at 1 MHz). The saturation magnetization, Ms, enhanced with increasing Li content, obeying the Globus model. The maximum Ms obtained for Li0.1Ni0.4Zn0.4Fe2.1O4 was 76 emu/g. The dielectric constant exhibited dispersive behavior with changing frequency. At lower frequency (<105 Hz), the dielectric constant was high, but fell down with increasing frequency. The ac conductivity and electric modulus remained low at lower frequency (<105 Hz), but ascended with increasing frequency. In contrast, the complex impedance spectra followed the reverse trend with changing frequency.

Photocatalytic Degradation of Phenol-red Over Sb2 S3 – Graphene Oxide composite

The photocatalytic degradation of phenol red has been studied in the presence of Sb2 S3 -graphene oxide (GO) as a composite photocatalyst. The composite was characterized using X-ray diffraction (XRD), Field emission scanning electron microscopy analysis (FESEM), Energy dispersive X-ray (EDX) and Fourier transform infrared (FT-IR) analyses. The XRD patterns indicated the formation of cubic inverse spinel structure and average particle size was found to be 14.26 nm. The photocatalytic activity of Sb2 S3 -GO was evaluated in photodegradation of phenol red dye under visible light. The effect of various parameters such as pH, the concentration of dye, amount of semiconductor and light intensity on the rate of degradation was also studied. Oxygen molecule radical anion was considered responsible for oxidative photodegradation of phenol red. A tentative mechanism has been proposed for this reaction.

Soft chemistry synthesis method of ZnAl2−xCrxO4 spinel: Structural, morphological, optical and photocatalytic properties

The precursor method was employed to prepare ZnAl 2-x Cr x O 4 (x = 0, 0.25, 0.5, 0.75, 1) using tartaric acid as a ligand. Five tartarate compounds were isolated as precursors for the obtaining of zinc aluminate and chromium-substituted zinc aluminate. These coordination compounds were characterized by elemental chemical analysis, infrared (IR) and ultraviolet visible (UV-Vis) spectroscopy, and thermal analysis. The influence of Cr 3+ substitution on the structure, morphology and optical properties of the synthesized mixed oxides was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), infrared, Raman and UV-Vis spectroscopy, and nitrogen adsorption – desorption analysis. The XRD patterns and Raman spectra confirmed the formation of spinel structure. The mean crystallite size varied from 18 to 22 nm. SEM and EDS showed uniform composition and microstructure of the ZnAl 2-x Cr x O 4 nanocrystalline powders. The values of the optical energy bandgap for the samples were found to be in the 3.92 – 2.85 eV range. The photocatalytic performance in the degradation reaction of Eosin Y (EY) under visible light irradiation was evaluated. The Eosin Y degradation efficiency values were obtained between 48 and 80% after 75 min. The best photocatalytic result was obtained for the sample with the highest amount of chromium.

Yttrium doping induced modifications in the electrical properties of cobalt zinc ferrite

Yttrium doped cobalt zinc nano-ferrites Co0.8Zn0.2Fe2-xYxO4 (x = 0, 0.01, 0.02, 0.03) were synthesized through the combustion method. For the formation and confirmation of single phase cubic spinel structure, X-ray diffraction is used. The average grain sizes from the Scherrer formula were below 50 nm. Microstructural features were obtained by scanning electron microscope. Electrical properties, such as dc resistivity as a function of temperature and ac conductivity as a function of frequency were studied for these samples. Room temperature dielectric constant (ε′) and dielectric loss (tan δ) are also studied as a function of frequency. The differentiation of dielectric properties ε′, tan δ, and ac conductivity (σac) with frequency imparts that the dispersion is because of Maxwell–Wagner type of interfacial polarization in general and the hopping of charge between Fe2+ and Fe3+ as well as Co2+ and Co3+ ions at B-sites. Electrical property study showed its dependence on the grain size.