Zinc substitution effect on the structural,spectroscopic and electrical properties of nanocrystalline MnFe2O4 spinel ferrite

This paper reports the structural, morphological, spectroscopic, dielectric, ac conductivity, and impedance properties of nanocrystalline Mn_1-xZn_xFe₂O₄. The nanocrystalline Mn–Zn ferrites were synthesized using a solvent-free combustion reaction method. The structural analysis using X-ray diffraction (XRD) pattern reveals the single-phase of all the samples and the Rietveld refined XRD patterns confirmed the cubic-spinel structure. The calculated crystallite size values increase from 8.5 nm to 19.6 nm with the Zn concentration. The surface morphological analysis using field emission scanning electron microscopy and the transmission electron microscopy confirms the nano size of the prepared ferrites. X-ray photoelectron spectroscopy was used to study the ionic state of the atoms present in the samples. Further, the high-resolution Mn 2p, Zn 2p, Fe 2p, and O 1s spectra of Mn_1-xZn_xFe₂O₄ does not result in the appearance of new peaks with Zn content, indicating that the Zn substitution does not change the ionic state of Mn, Zn, Fe, and O present in nanocrystalline Mn_1-xZn_xFe₂O₄. The investigated electrical properties show that the dielectric constant, tan δ and ac conductivity gradually decrease with increasing Zn substitution and the sample Mn_0·2Zn_0·8Fe₂O₄ has the lowest value of conductivity at 303 K. The ac conductivity measured at different temperatures shows the semiconducting nature of the ferrites. The impedance spectra analysis shows that the contribution of grain boundary is higher compared with the grain to the resistance. The obtained results suggest that the Zn substituted manganese ferrite nanoparticles can act as a promising candidate for high-frequency electronic devices applications.     

Magnetic interactions and hysteresis loops study of Co/CoFe2O4 nanoparticles

Co/CoFe₂O₄ nanoparticles with the mean size of 8.8, 10.8 and 16.9 nm were prepared by thermal decomposition of metal salts in the presence of citric acid. The X-ray diffraction patterns and Rietveld refinements confirmed coexistence of Co-ferrite and metallic cobalt phases in the nano-powders. Scanning electron microscope images showed an increase in particles aggregates mean diameter with increasing the annealing temperature. Magnetic hysteresis loops showed a demagnetization jump at low fields, which was attributed to different reversal fields of ferrite and the cobalt phases. Field-dependent behavior of maximum magnetization (M_max), remanence (M_r), squareness (S) and coercivity (H_c) were studied through minor loops measurements. The calculated S value of the loops showed a maximum, between anisotropy and coercive fields. A sharp increase in H_c of larger particles was observed with increasing the applied field when compared to smaller particles. Henkel plots showed that the samples are interacting. Negative deviation of Henkel plots from linear behavior and negative δm plots revealed the dominant role of dipole–dipole interactions in the nano-aggregates.     

Structural,magnetic, thermal and optical properties of Sn2+ cation doped magnetite nanoparticles

Tin doped nanomagnetites, Sn_xFe_3-xO₄, were synthesized with various concentrations of Sn²⁺ ion (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) by co-precipitation method. XRD, VSM, TG-DTA, SEM-EDX and UV–Vis were used to characterize and study the structural, magnetic, thermal, and optical properties of Sn_xFe_3-xO₄ nanoparticles. XRD confirmed the presence of cubic structure and spinel phase of tin doped magnetites. The d-spacing, lattice parameter, density, crystallite size and cation distribution were derived from the XRD analysis. The M − H curves exhibited changes in saturation magnetization (M_s), coercive field (H_c), remanent magnetization (M_r) and susceptibility (χ), with increasing concentration of non-magnetic Sn²⁺ ions. Differential thermal analysis was used to study the thermal stability of Sn_xFe_3-xO₄ nanoparticles. The SEM images revealed the surface morphology of the nanoparticles and the EDX spectra showed an increase in the Sn content and a corresponding decrease in the Fe content for the tin doped samples. The optical bandgap was found to be centered at 3.9 eV for the synthesized materials. This systematic study may be the first comprehensive report on synthesis and characterization of tin doped magnetites.     

Structural parameters,energy states and magnetic properties of the novel Se-doped NiFe2O4 ferrites as highly efficient electrocatalysts for HER

This study is devoted to NiFe₂O₄ with different masses of Se (NFO + x%Se) (x = 0.0–4.0%) spinel ferrite nanoparticles production and investigation. The results of the crystal structure, microstructure and magnetic properties are presented as a function of the chemical content of the NFO + x%Se. Superparamagnetic (at 300 K) and ferrimagnetic (at 10 K) states are observed for all samples in the wide magnetic field range. The field dependencies of the magnetization show that Se-substitution does not change the main magnetic characteristics when x<2.0%. We observe a non-linear dependence of magnetic parameters for sample with x ≥ 2.0% (for NFO+2%Se, we determine the increase of the main magnetic parameters for 20% of the average values and the minimum values belong to the NFO+3%Se). The undoped sample and NiFe₂O₄+x%Se are soft magnets and characterized by the low coercivity (varying in the range 560–647 Oe). At T = 10 K squareness ratio (Sq. = Mr/Ms) is in a range of (0.216–0.318). This indicates a preferable single-domain state of crystallites, which differs from the magnetic structure at T = 300 K. Furthermore, the NFO + x%Se (x = 2.0) have a low overpotential of about ?327 mV, and a small Tafel slope of 91 mV/dec, which makes it a better for HER (hydrogen evolution reaction) catalyst than the undoped NiFe₂O₄.     

Development of Co-doped MnFe2O4 nanoparticles for electrochemical supercapacitors

Transition metal ferrites are the essential components utilized in the latest modern-day technology and these include greater elements whose oxidation states and ionic radii are important for exploring their magnetic, optical, structural, and electrochemical properties. The present investigation was targeted on the preparation, physical and electrochemical characterizations of Co-doped MnFe₂O₄ nanomaterials such as 2 wt% Co-doped MnFe₂O₄, 4 Wt.% Co-doped MnFe₂O₄, and 8 Wt.% Co-doped MnFe₂O₄. More specifically, the study will focus on the techniques which have been employed to raise the specific capacitance of the metal oxides. Electrochemical properties such as cyclic voltammetry (CV), potentiostatic and impedance were used to analyse the super capacitive performance of Co-doped MnFe₂O₄ electrodes. Based on the outcomes, it is determined that 2 wt% of Co-doped MnFe₂O₄ has higher super capacitive behaviour than different samples. Precise capacitance for this nanocomposite from GCD was determined to be 551.39 F/g at a current density of 1 mA/cm². Accordingly, Co-doped MnFe₂O₄ may be utilized as a promising electrode for energy storage applications. It could be believed that this form of composites indicates excellent capability as electrochemical supercapacitors.     

Influence of Gd content on the structural,Raman spectroscopic and magnetic properties of CoFe2O4 nanoparticles synthesized by sol-gel route

The structural and magnetic properties of sol-gel synthesized Gd doped (x = 0.00 to 0.15) CoFe₂O₄ nanoparticles (NPs) have been studied. The x-ray diffraction (XRD) and FTIR spectroscopy along with Raman spectra confirmed the formation of face centered cubic inverse spinel structure. TEM images showed the NPs are well-dispersed with average particle size 30 nm. Room temperature magnetic measurement showed the value of coercivity fluctuates from 353 Oe to 1060 Oe for different % of Gd content. The maximum coercivity, saturation magnetization, magnetic moment, magnetic anisotropy, remnant magnetization found for 0.03% Gd content are 1060.19 Oe, 77.53 emu/gm, 3.29 μ, 4.11 × 10⁴ erg/cm³, 32.38 emu/gm, respectively. The large value of coercivity indicated that the interparticle interactions and crystalline anisotropy are high. Thus CoFe_2-xGd_xO₄ magnetic NPs might be a potential candidate for data processing, automotive and telecommunications.     

Impact of Zn doping on the dielectric and magnetic properties of CoFe2O4 nanoparticles

Owing to its unique magnetic, dielectric, electrical and catalytic properties, ferrite nanostructure materials gain vital importance in high frequency, memory, imaging, sensor, energy and biomedical applications. Doping is one of the strategies to manipulate the spinel ferrite structure, which could alter the physico-chemical properties. In the present work, Co_1-xZn_xFe₂O₄ ($x$ = 0, 0.1, 0.2, 0.3, and 0.4 wt%) nanoparticles were prepared by sol-gel auto-combustion method and its structural, morphological, vibrational, optical, electrical and magnetic properties were studied. The structural analysis affirms the single-phase cubic spinel structure of CoFe₂O₄. The crystallite size, lattice constant, unit cell, X-ray density, dislocation density and hopping length were significantly varied with Zn doping. The Fe–O stretching vibration was estimated by FTIR and Raman spectra. TEM micrographs show the agglomerated particles and it size varies between 10 and 56 nm. The Hall effect measurement shows the switching of charge carriers from n to p type. The dielectric constant (ε′) varies from 0.2 × 10³ to 1.2 × 10³ for different Zn doping. The VSM analysis shows relatively high saturation magnetization of 57 and 69 emu/g for ZC 0.1 and ZC 0.2 samples, respectively than that of undoped sample. All the prepared samples exhibit soft magnetic behaviour. Hence, it can be realized that the lower concentration of Zn ion doping significantly alters the magnetic properties of CoFe₂O₄ through variation in the cationic distribution and exchange interaction between the Co and Fe sites of the inverse spinel structure of CoFe₂O_4.     

Structural,dielectric and ferromagnetic behavior of (Zn,Co) co-doped SnO2 nanoparticles

Nanoparticles of basic composition Sn_0.94Zn_0.05Co_0.01O₂, Sn_0.92Zn_0.05Co_0.03O₂ and Sn_0.90Zn_0.05Co_0.05O₂ were synthesized by chemical precipitation method. The incorporation of Co and Zn in SnO₂ lattice introduced significant changes in the physical properties of all the three nanocrystals. The average particle size estimated from TEM data decreased from 15.71 to 6.41  nm with enhancement in concentration of oxygen vacancies as Co content is increased from 1 to 5 wt%. Increasing Co content enhanced the Sn:O atomic ratio as a result concentration of oxygen vacancies increased. The dielectric study revealed strong doping dependence. The dielectric parameters (ε′, tanδ and σ_ac) increased with increasing Co content and attained maximum values for 5% (Zn, Co) co-doped SnO₂ nanoparticles. The dielectric loss (ε′′) exhibited dispersion behavior and the Debye’s relaxation peaks observed in dielectric loss factor (tanδ), whose intensities increased with increasing Co content. The variation of dielectric properties and ac conductivity revealed that the dispersion is due to Maxwell-Wagner interfacial polarization and hopping of charge carriers between Sn⁺²/Sn⁺³ and Co⁺²/Co⁺³. The large dielectric constant of all samples made them interesting materials for device application. Magnetization measurements (M (H) loops) revealed enhancement in saturation magnetization with doping which is due to the formation of large amount of induced defects and oxygen vacancies in the samples. The present study clearly reveals doping dependent properties and the oxygen vacancies induced ferromagnetism in Zn, Co co-doped SnO₂ nanoparticles having applications in ultra-high dielectric materials, high frequency devices and spintronics.     

MnFe2O4 bulk,nanoparticles and film: A comparative study of structural and magnetic properties

MnFe₂O₄ bulk sample was synthesized by conventional solid state reaction method, at 1350 °C. Nanoparticles with mean size of 〈D〉_TEM=10.4(±1.1) nm were prepared by thermal decomposition of metal nitrates, at 350 °C. And a film sample was prepared by pulsed laser deposition of bulk ferrite on MgO(100) at substrate temperature of 600 °C. Then a comparative study of the structural and magnetic properties of the samples has been carried out using different measurements. X-ray diffraction pattern of bulk and nanoparticles samples confirmed formation of spinel phase. The film sample showed an epitaxial growth on MgO in (400) direction. Saturation magnetization of nanoparticles at 300 K, M_S=33 emu/g, was comparable with film sample, M_S=38 emu/g, both being ∼2.5 times smaller than that of bulk sample (M_S=82 emu/g). The results showed the importance of surface effects in the film sample and nanoparticles. The obtained zero coercivity of bulk sample at 300 K and the low value of 8 Oe at 5 K is attributed to soft magnetic behavior of the MnFe₂O₄. On the other hand, nanoparticles showed superparamagnetic behavior at 300 K; and blocked state with a large coercivity of 730 Oe at 5 K. The film sample showed non-zero corecivity at both 5 and 300 K which reveals higher magnetic anisotropy of film compared to the bulk ferrite.     

Effect of Ni2+ substitution on structural,magnetic, dielectric and optical properties of mixed spinel CoFe2O4 nanoparticles

Nanoparticles of Co_1−xNi_xFe₂O₄ with x=0.0, 0.10, 0.20, 0.30, 0.40 and 0.50 were synthesized by co-precipitation method. The structural analysis reveals the formation of single phase cubic spinel structure with a narrow size distribution between 13–17 nm. Transmission electron microscope images are in agreement with size of nanoparticles calculated from XRD. The field emission scanning electron microscope images confirmed the presence of nano-sized grains with porous morphology. The X-ray photoelectron spectroscopy analysis confirmed the presence of Fe²⁺ ions with Fe³⁺. Room temperature magnetic measurements showed the strong influence of Ni²⁺ doping on saturation magnetization and coercivity. The saturation magnetization decreases from 91 emu/gm to 44 emu/gm for x=0.0–0.50 samples. Lower magnetic moment of Ni²⁺ (2 µ_B) ions in comparison to that of Co²⁺ (3 µ_B) ions is responsible for this reduction. Similarly, overall coercivity decreased from 1010 Oe to 832 Oe for x=0.0–0.50 samples and depends on crystallite size. Cation distribution has been proposed from XRD analysis and magnetization data. Electron spin resonance spectra suggested the dominancy of superexchange interactions in Co_1−xNi_xFe₂O₄ samples. The optical analysis indicates that Co_1−xNi_xFe₂O₄ is an indirect band gap material and band gap increases with increasing Ni²⁺ concentration. Dispersion behavior with increasing frequency is observed for both dielectric constant and loss tangent. The conduction process predominantly takes place through grain boundary volume. Grain boundary resistance increases with Ni²⁺ ion concentration.     

Synthesis,characterization and photocatalytic activity study of aluminium doped BiSbO4 microflakes

Metal oxides have an extraordinary ability to generate charge carriers with significant importance in environmental remediation. For the degradation of different dyes, a one-step hydrothermal method was adopted to synthesize Al-doped BiSbO_4. While bismuth antimonate composite with reduced graphene oxide was synthesized by the simple ultra-sonication method. To investigate the structural confirmation, X-ray diffraction (XRD) was used. For studying morphology, scanning electron microscopy (SEM) was conducted. UV–Visible spectroscopy (UV) and Fourier transform infrared spectroscopy (FTIR) were used to observe the optical properties and vibrational modes of the as-synthesized BiSbO₄ nanoparticles and doped Al–BiSbO₄. The above-mentioned studies verify the formation of nanoparticles of Al-doped BiSbO₄. The synthesized composite was used to degrade the organic dyes such as methylene blue and crystal violet. The degradation efficiency of doped, undoped and composite is studied and compared. The results indicate the extraordinary efficiency of BiSbO₄/rGO composite to doped and bare samples for the degradation of dyes. It is confirmed by the degradation of different dyes that the BiSbO₄/rGO composite shows the best catalytic efficiency.     

Enhanced sunlight driven photocatalytic activity and electrochemical sensing properties of Ce-doped MnFe2O4 nano magnetic ferrites

This research deals with the facile combustion synthesis of manganese ferrite (MFO) nanoparticle with different cerium concentration and their potential application as an efficient photocatalyst and chemical sensor. The concentration of introduced cerium affects the size, structure, compositional, morphological, optical, photoluminescence and magnetic properties of the ferrite nanoparticle. The X-ray diffraction pattern affirmed the arrangement of cubic spinel structure with the formation of secondary phase CeO₂ as the cerium concentration exceed 3 mol%. SEM micrographs revealed irregular morphology with more number of pores and voids. HRTEM along with SAED pattern revealed the crystalline cubic nature. The optical band gap deduced from UV–Vis-DRS spectra was observed to be in the range 2.3–2.8 eV. PL studies indicated a significant minimization in combination of electrons & holes in MnFe₂O₄ on addition of Ce dopant. VSM investigation demonstrated the soft magnetic nature of the prepared sample with moderate magnetization value. An excellent photocatalytic performance of Cerium doped MFO (3 mol%) towards MB and AR dye degradation was found to be 1.5 and 1.67 times more compared to host matrix under Sunlight irradiation that correlated to reduced band gap, Ce dopant and efficient separation of charge carriers. Cerium doped MFO (3 mol%) have high specific capacitance value of 471.7 and 1546.8 Fg^-1 for NaNO₃ and HCl electrolytes respectively, indicating the pseudo capacitance nature due to which it can be used as a supercapacitor. The synthesized nanoparticles can sense d-Glucose and Paracetamol even at a lower concentration varying from 1 to 10 mM. The synthesized Ce-doped MnFe₂O₄ nanomaterials have great potential to be used in the future production of promising active photocatalysts and sensitive chemical sensors for the identification and degradation of toxic industrial dyes for improved safety in the fields of environment and health care.     

Structural,magnetic and dielectric properties of the novel magnetic spinel compounds ZnCoSnO4 and ZnCoTiO4

The transparent semiconductor Zn₂SnO₄ with cubic spinel structure and the isostructural Zn₂TiO₄ have been magnetically doped with Co²⁺. ZnCoSnO₄ and ZnCoTiO₄ exhibit ferrimagnetism below T_N ≈ 13?K and T_N ≈ 17?K. Ferrimagnetic moments are evident in M vs H curves below T_N by small hysteresis. Fits to strictly linear Curie-Weiss plots above T_N give μ_eff ≈ 4.86 μ_B and ≈4.91 μ_B for ZnCoSnO₄ and ZnCoTiO₄, above theoretical predictions. Impedance spectroscopy data from sintered ceramic can be fitted with a standard equivalent circuit model based on two RC elements for bulk and GB areas. The relative dielectric permittivity of the bulk is ≈20 and ≈30 for Zn₂SnO₄ and Zn₂TiO₄. The semiconducting ZnCoSnO₄ and ZnCoTiO₄ceramics exhibit bulk resistivity of ≈1 10⁶?Ω?cm and ≈1 10⁵?Ω?cm at 560?K (287?°C), and bulk activation energies of E_A ≈ 1.2?eV and 1.1?eV.     

Effect of bimetallic (Ni and Co) substitution on magnetic properties of MnFe2O4 nanoparticles

Nickel and cobalt substituted manganese ferrite nanoparticles (NPs) with the chemical composition Ni_xCo_xMn_1–2xFe₂O₄ (0.0≤x≤0.5) NPs were synthesized by one-pot microwave combustion route. The effect of co-substitution (Ni, Co) on structural, morphological and magnetic properties of MnFe₂O₄ NPs was investigated using XRD, FT-IR, SEM, VSM and Mössbauer spectroscopic techniques. The cation distribution of all products were also calculated. Both XRD and FT-IR analyses confirmed the synthesis of single phase spinel cubic product for all the substitutions. Lattice constant decreases with the increase in concentration of both Co and Ni in the products. From ⁵⁷Fe Mössbauer spectroscopy data, the variations in line width, isomer shift, quadrupole splitting and hyperfine magnetic field values with Mn²⁺, Ni²⁺ and Co²⁺ substitution have been determined. While the Mössbauer spectra collected at room temperature for the all samples are composed of magnetic sextets, the superparamagnetic doublet is also formed for MnFe₂O₄ and Ni_0.2Co_0.2Mn_0.6Fe₂O₄ NPs. The magnetization and Mössbauer measurements verify that MnFe₂O₄ and Ni_0.2Co_0.2Mn_0.6Fe₂O₄ NPs have superparamagnetic character. The saturation and remanence magnetizations, magnetic moment and coercive field were determined for all the samples. Room temperature VSM measurements reveals saturation magnetization value close to the bulk one. It has been observed that the saturation magnetization and coercive field increase with respect to the Ni and Co concentrations.     

Impact of temperature-induced oxygen vacancies in polyhedron MnFe2O4 nanoparticles: As excellent electrochemical sensor,supercapacitor and active photocatalyst

Here, we investigate the effect of temperature on solution combustion synthesized MnFe₂O₄ nanoparticles (NPs) as supercapacitor electrode material that would affect the structural, optical, electrochemical, magnetic and sensing properties. The variation in temperature influences the structure and morphology of synthesized NPs which in turn produces defect states in NPs. Powder X-ray diffraction studies confirms the presence of cubic spinel structure with increase in crystallinity and crystallite size with increase in temperature. Scanning electron microscopy analysis indicates the morphology change in NPs from spherical to network like interlinking to the formation of polyhedron structure at higher temperature. Photoluminescence, energy dispersive X-ray analysis, X-ray photoelectron scpectroscopy and UV-visible diffused reflectance spectroscopy studies emphasize the increase in surface oxygen vacancies concentration with narrowing of band gap from 2.9 to 2.5 eV. Electrochemical studies designate the excellent performance and desirable cyclic stability of synthesized NPs. In particular, the specific capacitance of synthesized NP increases with increase in temperature, reaching highest specific capacitance from CV was 297.7 F/g for 0.1 M HCl and 158.85 F/g for 0.1 M NaNO₃ electrolytes for NP synthesized at 500 °C. The synthesized NPs show excellent stability with high capacity retention in both the electrolytes. The graphite modified electrode can also sense Paracetamol and d-Glucose at a very low concentration of 1–5 mM. Meanwhile, it acts as a very good photocatalyst to decolourize Methylene Blue and Alizarin Red S dye under Sunlight illumination due to the increase in concentration of surface oxygen vacancies with narrow band gap. Finally, the synthesized MnFe₂O₄ NP can be used as a potential supercapacitor electrode with excellent stability and recyclability, to sense the analyte even at very low concentration and also act as a photocatalyst with high recyclability with the help of magnetic nature towards environmental cleaning.     

Effect of Mg doping on magnetic,and dielectric properties of NiCr2O4 nanoparticles

The structural, magnetic, and dielectric properties of spinel Magnesium (Mg) doped Nickel chromite (NiCr₂O₄) nanoparticles (NPs) have been studied in detail. The X-ray powder diffraction exhibited normal spinel phase formation of Mg_xNi_1-xCr₂O₄ (x = 0, 0.2, 0.4, 0.6, and 1) NPs with a maximum average crystallite size of about 44 nm for x = 0.2 composition. The FTIR spectra of these NPs revealed the characteristic Ni–O and Mg–O and Cr–O bands around 639 cm^?1 and 497 cm^?1, respectively which confirmed the spinel structure. Temperature-dependent zero field cooled and field cooled graphs of NiCr₂O₄ NPs showed phase changes from ferrimagnetic to paramagnetic state at 86 K, while MgCr₂O₄ NPs showed antiferromagnetic (AFM) transition at Neel temperature (T_N) at 15 K due to corner-sharing of Cr³⁺ ions at a tetrahedral lattice site resulting in a highly magnetic frustrated structure. The field dependent magnetization (M ? H) loops of Mg_xNi_1-xCr₂O₄ NPs confirmed the competing AFM interactions and ferrimagnetic interactions resulting in a sharp decreased saturation magnetization with Mg doping. Dielectric constant, dielectric loss, and ac conductivity of these NPs showed size-dependent variation and depicted maximum value at x = 0.2 Mg concentration. In summary, the magnetic and dielectric properties of Mg doped NiCr₂O₄ NPs were modified by variations in the average crystallite size and magnetic exchange interactions, which may be suitable for different technological applications.     

Zirconium substituted spinel nano-ferrite Mg0.2Co0.8Fe2O4 particles and their hybrids with reduced graphene oxide for photocatalytic and other potential applications

Zirconium substituted magnesium cobalt ferrite (Zr_xMg_0.2-xCo_0.8-xFe₂O₄) nanoparticles and their nano-heterostructures with graphene were synthesized by co-precipitation and ultra-sonication route respectively. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopic (SEM) analysis was done to study the effect of Zr⁴⁺ substitution on structural properties, surface morphology, dielectric and current-voltage properties of nanoparticles. The crystallite size of nanoparticles was found in the range of 23–28 nm. XRD pattern analysis confirmed the spinel structure of nanoparticles. Graphene synthesized by modified Hummer's method was utilized as substrate to prepare the heterostructures with ferrite particles. Dispersion of nanoparticles on the surface of rGO sheets was confirmed by SEM analysis. Enhanced photocatalytic activity of nanoparticles and graphene based nano-heterostructures was observed under visible light irradiation. During the current-voltage measurements, decrease in electrical resistivity of nanoparticles was observed. Dielectric measurements were performed within the frequency range 1 MHz–3 GHz. Electrochemical impedance spectroscopy was done to evaluate the kinetic parameters and charge-transfer resistance (R_ct) at electrode interface. Enhanced photocatalytic applications, suggested that Zr_xMg_0.2-xCo_0.8-xFe₂O₄ nanoparticles and graphene based nano-heterostructures can be used for degradation of various organic based pollutants in drinking water.     

The role of Co ion substitution in SnFe2O4 spinel ferrite nanoparticles: Study of structural,vibrational, magnetic and optical properties

In order to accurately investigate the effect of cobalt substitutions in tin ferrite (SnFe₂O₄) properties, we prepared Co_xSn_1-xFe₂O₄ nanoparticles for different Co concentrations, x?=?0.0, 0.25, 0.50, 0.75, and 1.00 using a simple co-precipitation method. X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), field emission scanning electron microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDX) and diffuse reflectance spectra (DRS) are used to study of structural, magnetic, morphology, and optical properties. The XRD and FTIR results confirmed the formation of cubic spinel structure. The lattice parameter and unit cell volume of tin ferrite nanoparticles were found to increase by entering and increasing Co⁺² content in 0.25, and then significantly decrease for higher contents. In accordance with the XRD results, a slight shift in main band υ₁ (${\mathit{Fe}}_{\mathrm{tetra}}^{+3}?O)$ to lower wavenumber and then to higher wavenumber were observed in the IR spectra of Co content x?<?0.25 and x?>?0.25, respectively. In turn to, saturation magnetization, remanent magnetization and anisotropy constant of SnFe₂O₄ nanoparticles were gradually increased for x?=?0.50 and then decreased for x?>?0.50.