Vibrating Sample Magnetometer Studies Research Articles

Physical properties of nanosized (x)NiO/(1−x)CdFe2O4 composites

This study investigates the optical and magnetic properties of nanosized (x)NiO/(1−x)CdFe2O4 (x = 0.1, 0.2, 0.3, 0.4, 0.5, and 1) composites. The samples were synthesized using the wet coprecipitation technique. The X-ray Diffraction patterns demonstrated the formation of Nickel Oxide (NiO) and Cadmium Ferrite (CdFe2O4) phases without any chemical reaction between them. Fourier Transform Infrared results confirm the formation of pure NiO, pure CdFe2O4, and nanosized NiO/CdFe2O4 composites. Transmission Electron Microscopy micrographs show agglomeration between the nanoparticles, demonstrating the magnetic interaction between the oxide and ferrite phases. High-Resolution Transmission Electron Microscopy results verify the presence of NiO and CdFe2O4 phases in each nanosized composite without impurities, which is consistent with the XRD data. The ultraviolet–visible spectroscopy results confirmed that HCl is a better solvent than ethanol in investigating the optical properties of nanosized oxide/ferrite composites. Photoluminescence spectra exhibited asymmetricity owing to the presence of various emission peaks, which reveals the distribution of defect states within the bandgap of the nanosized composites. The Mössbauer spectra of the nanosized composites comprised an asymmetrical doublet at 300 K and an asymmetrical centered doublet within minor sextets at 77 K. Vibrating Sample Magnetometer study showed a shift at 77 K, which can be attributed to the spontaneous exchange bias effect. The magnetic parameters extracted from the M − H loops of all the synthesized nanosized composites at 77 K are higher than those at 300 K.

Influence of Lanthanum‐doping on photocatalytic activity of magnetic BiFeO3 nanocrystals for sunlight driven degradation of metachrome yellow

In the present work, the structural and photocatalytic activity of BiFeO3 (BFO) and Lanthanum doped BiFeO3 (LBFO; La0.2Bi0.8FeO3) nanocrystals (NCs) towards photodegradation of Metachrome Yellow dye were examined, hitherto unreported in the literature. The bismuth ferrite samples with a prominent rhombohedral phase at room temperature were prepared by sol-gel method, and investigated using multiple structural and spectroscopic tools. La doped BFO was found to be superior in terms of phase formation, photoluminescence quenching and visible light absorption. Further, La doped sample showed higher photodegradation efficiency of 71% compared to 50% by pure BFO NCs for Metachrome Yellow under natural sunlight. The enhanced photocatalytic ability of La doped BFO could be attributed to the increased polarization in the multiferroic oxide that promoted charge separation, besides the small bandgap well into the visible light region of the spectrum and the increased surface hydroxyl groups aiding the redox photodegradation reactions. Vibrating sample magnetometer studies of BFO and LBFO NCs revealed ferrimagnetic nature for the nanomaterials making it a potential photocatalyst for practical applications, as it could be magnetically separated post usage in waterbodies.

Influence of Nd3+ substituted Co0.5Ni0.5Fe2O4 ferrite on structural, morphological, dc electrical resistivity and magnetic properties

Solid-state reaction method was incorporated for the preparation of rare earth Nd3+ substituted Co-Ni ferrite materials Co0.5Ni0.5Fe2-xNdxO4 where × = 0.0, 0.03, 0.06, and 0.09. They were characterized by XRD, SEM, FTIR, Raman spectrometer, DC electrical resistivity, and Vibrating sample magnetometer studies for their structural, morphological, infrared dc electrical resistivity, and magnetic properties.XRD studiesof all the samples revealed a single-phase pure cubic spinel structure. Thecrystallite size decreases from 44 nm to 32 nm and lattice constant increases with Nd3+content. The grain size was found in the range of 2–3.5 µm. FTIR supports the XRD results. Showing two absorption bands near (octahedral site) 400 cm−1and (tetrahedral site) 600 cm−1. The DC resistivity is increased with Nd3+ content increases shows their semiconducting nature and activation energy varies from 0.52 eV to 0.62 eV. The saturation magnetization increases from 51.22 emu/g to 56.33 emu/g with the increase in doping. Their coercivity depends on the particle size and it decreases from 365 Oe to 153 Oe.

Structural and Magnetic Properties of Co0.9Zn0.1Fe2O4 Ferrite Nanoparticles Synthesized by Chemical Co‐Precipitation Method

AbstractIn this study, the structural and magnetic properties of Co0.9Zn0.1Fe2O4 ferrite nanoparticles are prepared by using chemical co‐precipitation method and characterized with X‐ray diffraction (XRD) and vibrating sample magnetometer (VSM). The structural results show that the particles have a formation of single‐phase cubic spinel structure and that the particles have a nano scale, with a clear agglomeration between the particles. The crystallite size of the sample is found 6.21 nm by using Scherer's formula, while the lattice parameters is 8.38 Å. The VSM study shows the saturation magnetization (Ms) 30.18 emu g‐1 and coercivity (Hc) 500 Oe along with hysteresis and to calculate the Ms values the Law of approach to saturation is used. The dried sample of ferrite is characterized with an FTIR‐spectrophotometer in wave number range of 4200–800 cm−1.

Synthesis, structural and microwave absorption properties of Cr-doped zinc lanthanum nanoferrites Zn1-Cr La0.1Fe1.9O4 (x=0.09, 0.18, 0.27 and 0.36)

Cr-doped zinc-lanthanum nanoferrites Zn 1- x Cr x La 0.1 Fe 1.9 O 4 ( x = 0.09, 0.18, 0.27, and 0.36) were successfully synthesized using sonochemical reactors. Effect of powder production parameters were extensively studied and powder characterization was performed. Existence of cubic spinel structures in the prepared nanoferrites with the average crystallite size ranging from 35 to 51 nm was confirmed by X-ray diffraction studies. An electrochemical impedance analyzer was used to measure the dielectric constant ( ε ′), loss tangent (tan δ), and complex dielectric constant ( ε ") with respect to frequency and composition ratio. Maxwell–Wagner polarization and hopping mechanism were calculated to distinguish the variations in ε ′, tan δ, and ε ". The Nyquist impedance plots for nanoferrites revealed the pseudocapacitance as well as resistive behavior. Vibrating sample magnetometer studies reveled the ferromagnetic behavior of nanoferrites. Substantially increased saturation magnetization and decreased coercivity were noted with respect to increased Cr 2+ ions in the prepared nanoferrites. It was found that the addition of chromium in Zn 1- x Cr x La 0.1 Fe 1.9 O 4 nanoferrites enhances the optical, electrical, and magnetic properties of the nanoferrites.

Room temperature ferromagnetism and dielectric properties of cobalt doped Tin Selenide for spintronic applications

Doping can induce and tune many physical properties of a semiconductor host lattice. Here, we report the effect of cobalt doping on optical, dielectric, and magnetic properties of SnSe. We have synthesized Cobalt doped SnSe (CoxSn1-xSe) polycrystals with x = 0.00, 0.01, 0.03, 0.05, 0.10 and 0.20 using hydrothermal method. The single-phase was confirmed from X-ray Diffraction. Morphology of CoxSn1-xSe polycrystals was examined through Scanning Electron Microscope and it revealed a 3D flower-like morphology for undoped and CoxSn1-xSe till x = 0.05. The morphology changed to rod-like shapes for higher compositions of Co. The bandgaps of CoxSn1-xSe were reduced as determined from UV–Vis–NIR Diffuse Reflectance Spectroscopy. Dielectric properties of the samples were studied at room temperature in a frequency range from 100 Hz to 12 MHz. Vibrating Sample Magnetometer studies revealed the ferromagnetism for all the samples at room temperature. The results indicate the possible applications of the material in spintronic devices.

Temperature dependence of atomic clusters and magnetic properties of α-phase Fe-V alloy by Mössbauer and VSM studies

In this work, α-phase Fe-12 V alloy (at.%) with high total magnetostriction is selected to perform Mössbauer and Vibrating Sample Magnetometer (VSM) measurements to investigate the temperature dependence of atomic clusters and the magnetic properties. The results show that with increasing temperature, the ferromagnetism firstly drops and then slightly increases, and finally decreases severely, which is mainly determined by the variations of the three kinds of atomic clusters (Fe-rich, V-rich and free-Fe) in the alloy. The hyperfine magnetic field, which decreases with temperature, is always dominated by the Fe-rich clusters. The atomic combination of the free-Fe clusters also determines the magnetic properties in the temperature range from room temperature to 600 °C; however, the free-Fe clusters contribution to the hyperfine magnetic fields tends to become zero above 600 °C, whereas that of the V-rich becomes obvious. When the temperature is high enough, the hyperfine magnetic field decreases sharply due to the destruction of the ordered Fe-rich state. VSM was selected to understand the relationship between the magnetic moment and the heating temperature, and the Curie temperature (TC=836.36 °C) of the Fe-12 V alloy was obtained as well. Finally, the formula reflecting the magnetic moment of the α-phase Fe-12 V alloy varying with temperature is also successfully derived.

Effect of current density on electrodeposited cobalt ferrous tungsten magnetic thin films

Co-Fe-W electrodeposited magnetic thin film properties were studied to identify the possible applications in different area. The film was prepared using the electrodeposition method with different current densities, in order to get the uniform deposition with different thickness. A vibrating sample magnetometer studies provide the value of magnetic saturation (Ms=0.112emu), retentivity (Mr=0.020emu) and coercivity (Hc=88.95Oe). The prepared film is (45min, thickness is 3.10μm) more suitable to develop tiny integrated memory devices. X-ray diffraction studies (XRD) confirm the cubic crystalline nature of the prepared thin films. Surface morphology analysis clearly shows the uniform thickness (0.2 μm) of the thin film [scanning electron microscope (SEM)]. The highest percentage of Co, Fe and W composition in the thin films were obtained by using energy dispersive X-ray analysis. The maximum hardness value is 212/7.5 mAcm2 for 45min and best adhesion with desirable magnetic properties have been reported in the present communication.

Structural, optical and magnetic characterizations of nanoparticles spinel Zn(1-x)MxAl2O4 (M = Co and Ni) synthesized by microwave combustion method

Spinel Zn(1-x)MxAl2O4 (M = Co and Ni) nanoparticles were prepared using the microwave combustion technique. Different compositions of ratios with formula Zn(1-x)MxAl2O4 (0.5 ≤ x ≤ 1.0) were prepared by substitution of Zn+2 ions with Co+2 and Ni+2 ions. Structural properties of the resultant spinel compositions were characterized by Energy Dispersive X-ray, X-ray diffraction and infrared spectroscopy. The surface topology and determination of particle size of the nanopowder were characterized by high-resolution scanning electron microscope. Magnetization and spectra of the optical absorption at room temperature were measured. The effects of substitution Co+2 and Ni+2 cations on optical and magnetic properties of ZnAl2O4 spinel were studied. Analysis of UV–Vis absorbance showed that the optical band gaps of the samples decrease linearly with increasing Co+2 and Ni+2 ratios. Vibrating Sample Magnetometer study showed that an adding of Co+2 and Ni+2 ions to ZnAl2O4 leads to converse diamagnetic zinc aluminate to paramagnetic and superparamagnetic materials.

Room temperature ferromagnetic behavior of nickel-doped zinc oxide dilute magnetic semiconductor for spintronics applications

Abstract The multifunctional zinc oxide (ZnO) nanoparticles were economically grown through a simple co-precipitation technique. Ni-doped (1, 3, and 5 wt%) ZnO nanoparticles were also grown to comprehend their influence on the ferromagnetic property of the ZnO, especially at room temperature. The structural and surface morphological features of the prepared nanoparticles were studied through X-ray diffraction (XRD) and Scanning electron microscopy (SEM) techniques, respectively. Diffused reflectance, Photoluminescence, and Fourier transform infrared spectroscopic analyses were also carried out to understand the consequence of Ni doping on the ZnO nanostructure. The secondary phase formations such as NiO and NiO2 elucidate the solid solubility limit of three percent of nickel in the ZnO matrix. Size-strain analysis was performed to evaluate the crystallite size and apparent strain values. An increase in the agglomeration of particles is evidenced by SEM micrographs with an increase in the Ni doping percentage. The bandgap measurements showed a redshift from 3.25 to 3.18 eV for the Ni-doped nanoparticles. Photoluminescence study reveals the existence of lattice defects including interstitials and vacancies in the synthesized nanostructures. The vibrating sample magnetometer studies divulge that 3% Ni-doped ZnO nanoparticles show an intense ferromagnetic property at room temperature. These experimental observations manifested that the Ni-doped ZnO nanoparticles are potential candidates for spintronics device applications.

Study of structural and magnetic properties of aluminium-substituted nanosized barium hexaferrite prepared by sol–gel auto-combustion technique

M-type nanosized barium hexaferrite BaMexFe12−xO19 (Me = Al3+ and x = 0.0, 0.4, 0.8) was synthesized by sol–gel auto-combustion method using urea as a fuel. Characterization of prepared sample was done by using different techniques, such as XRD (X-ray diffractometer), SEM (scanning electron microscope), EDAX (energy dispersive X-ray analysis), TEM (transmission electron microscope) and vibrating sample magnetometer (VSM). XRD studies show the formation of M-type barium hexagonal ferrite with space group P63/mmc. The effect of substitution of Al3+ ion for Fe3+ ion on the unit cell parameter, density, porosity has been studied. The SEM study shows that the samples exhibit spherical-shaped particles and agglomeration of individual particles in some parts. EDAX study confirms the elemental composition of prepared samples. TEM images confirm the nanosize of prepared samples. The VSM or magnetic study reveals that the saturation magnetization (Ms) value decreases from 57.1 to 33.6 emu g−1, while coercivity (Hc) value increases from 1737 to 2071 Gauss by the substitution of Al content. Substitution of Al3+ ion in barium hexaferrite significantly improves the magnetic properties.

Investigation on Multiferroic Properties and Conduction Mechanism in Cobalt Doped Bi0.9Nd0.1FeO3 Solid Solutions

Bi0.9Nd0. 1Fe1–x Co x O3 (x = 0.025, 0.050, 0.075 and 0.1) solid solutions have been synthesized by doping of Co3+ at the Fe3+ site using solid-state reaction method. The prepared solid solutions have been investigated for their structural, magnetic, ferroelectric and magneto-dielectric properties and conduction mechanism. The XRD study reveals that all the solid solutions possess a rhombohedral symmetry. The vibrating sample magnetometer study reveals that all the samples possess magnetic orders and the remnant magnetization has been found to be increased from 0.2388 emu/g for x = 0.025 to 0.7112 emu/g for x = 0.1. The non-Debye type dielectric relaxation has been investigated for all the samples. The frequency dependent ac conductivity data follows Jonscher’s Power law. Variation of exponent n versus temperature follows the overlapping large polaron tunneling conduction model. The maximum value of remanent polarization (∼0.152 μC/cm2) was found for x = 0.1. All the samples exhibit positive magneto-dielectric response in the low-frequency region with the highest magneto-capacitance value of 13.54% at 500 Hz for sample x = 0.1.

Nano Synthesis and Characterization of Co and Mn Co-doped ZnO by Solution Combustion Technique

Pure zinc oxide (ZnO) and Co and Mn co-doped ZnO nanoparticles were synthesized via a solution combustion technique. Structural, compositional, morphological, functional, optical, magnetization, and photoluminescence properties were examined. X-ray diffraction studies confirmed the hexagonal structure, and the average crystallite size of the synthesized samples was found to be around 20 to 30 nm. From the SEM analysis, all synthesized samples were spherical. Energy dispersion spectra confirm the presence of all selective elements in the synthesized samples. From UV-Vis spectra, we observed that there is decrease in band gap with increase in Co/Mn concentration. From photoluminescence (PL) studies, a decrease in the rate of recombination of electron-hole pair generation is observed. Experiments carried out using vibrating sample magnetometer studies revealed magnetic properties that indicate ferromagnetism in synthesized samples at room temperature. This material offers enormous potential to develop spintronics and optoelectronic materials due to its low cost and good yield.

Influence of Ni2+ doping in the structural, magnetic and optical properties of MnFe2O4 spinel ferrite synthesized by sol–gel facilitated microwave method

Transition of superparamagnetic behaviour to ferromagnetic behaviour is earned by incorporating a divalent transition metal ion Ni2+into the lattice of nanocrystalline MnFe2O4 and consequently evolves as a soft magnet. The present work exploits sol–gel facilitated microwave combustion method to synthesize the nickel doped manganese ferrite nanocrystals Mn1-xNixFe2O4(0.0 ≤ x ≥ 0.5). The resulting nanocrystals were characterised by X-ray diffraction (XRD), Scanning electron microscope with energy dispersive X-ray analysis (SEM-EDAX), UV–Visible Diffuse reflectance spectroscopy (UV-DRS) and Vibrating sample magnetometer (VSM) studies. Within the tested calcination temperature (700 °C/4hr) it was feasible to procure nanocrystalline magnetic ferrites with a single crystalline phase confirmed by XRD analysis leading to a cubic spinel structure with a prominent superparamagnetic regime. The VSM studies evidences a diminishing saturation magnetization (Ms) from 66.89 to 49.42 emu/g, a decrease in magnetic moment (µB) and an increase in coercivity (Hc) from 51.45 kOe to 66.36 kOe with the higher doping of Ni2+ions in the lattice. The crystalline size of the synthesized ferrites varied between 30 and 40 nm illustrated by XRD analysis and an average particle size of 70 nm evidenced by SEM results. An increase in band gap with an increase in Ni2+could be observed from the UV-DRS results. The analysed characteristics of these ferrites could be exploited in places of minimum energy dissipation such as transformer and motor cores.

Rapid green-synthesis of TiO2 nanoparticles for therapeutic applications.

Nanoparticles (NPs) with sizes ranging from 2 nm to 1 μm find various applications in the field of theranostics. Moreover, if eco-friendly methods are opted for the synthesis of biocompatible and less toxic NPs, then that's a huge success. Titanium dioxide nanoparticles (TiO2 NPs) have been vigorously studied for their use in medical implants, photodynamic therapy, drug delivery, biosensing and as antimicrobial agents. The present study reports the green-synthesis of TiO2 NPs for the first-time using extracts of black pepper (Piper nigrum), coriander (Coriandrum sativum) and clove (Syzygium aromaticum). All three samples of TiO2 NPs were synthesized via a modified sol–gel method under similar environmental conditions. Similar treatments were given to the samples. The procedure adopted for the synthesis ensures the use of non-toxic materials, no production of toxic by-products and rapid synthesis of the TiO2 NPs. The NPs were characterized by X-ray diffraction, high resolution-transmission electron microscopy, energy dispersive spectroscopy, field emission scanning electron microscopy and selected area electron diffraction which confirmed the formation, morphology, crystallinity and size of the TiO2 NPs. These characterizations displayed the similarity index of all three samples. However, photoluminescence and vibrating sample magnetometer studies highlighted the differences among the three samples. All three samples of NPs obtained had a size range of 5–20 nm. Further, the findings showed that different plant extracts result in TiO2 NPs with moderately different characteristics. Furthermore, the samples were analysed for their drug-encapsulation efficiency using UV-visible spectrophotometry. Among all three samples, the NPs synthesised using black pepper exhibited the maximum encapsulation efficiency. The study concludes that the plant's bio-profile is responsible for bringing about changes in the traits of the resulting nanoparticles. Thus, the extracts from different plants have the ability to manipulate the properties of the synthesized NPs. These findings can help to understand the role and importance of the plants in synthesizing NPs for biomedical applications. A further detailed study in this field can help researchers to understand the influence of the plant's biochemistry in shaping the NPs.

Reitveld Refinement and Derivative Spectroscopy of Nanoparticles of Soft Ferrites (MgNiFe)

MgNi ferrite nanoparticles were synthesized using an aqueous sol-gel method for targeted drug delivery and other electronic applications. The nitrates of Mg, Ni and iron were used as precursors and citric acid as fuel in a water based synthesis. The nanoparticles so prepared were characterized using X-ray diffraction technique (XRD), field emission scanning electron microscopy (FESEM); transmission electron microscope (TEM), vibrating sample magnetometer (VSM), FTIR spectroscopy and their respective derivatives. The results of XRD patterns are indicative of formation of ferrite nanoparticles and crystallite sizes were obtained using Williamson-Hall plot. Reitveld refinement was applied to assure about the crystal structure and allied parameters. The magnetic analysis of the prepared samples have been performed by VSM and found that the synthesized nanoparticles exhibited nearly superparamagnetic behaviour having high magnetic saturation (Ms) and negligible coercivity (HC). The FTIR plots confirm the formation of spinel structure of the MgNi ferrites. The formation of spinel ferrite structure is confirmed by absorption bands corresponds to vibration of tetrahedral (A) site and by absorption bands corresponds to the octahedral (B) site. Reitveld refinement and derivative spectroscopic analysis give detailed analysis from XRD, VSM and FTIR studies and helps to conclude detailed and important findings.

Synthesis and characterizations of Pd/Mn(Mn1.36Pd0.64)O4 nanocomposite: An experimental and theoretical approach

Due to the growing environmental issues and high energy consumption, there is an emergent need to synthesize the multifunctional materials to reduce energy consumption. Hence, we synthesized the Pd/Mn(Mn1·36Pd0.64)O4 nanocomposite by a simple sol-gel process, and studied their Crystal structure, surface morphology, optical absorbance, electrochemical and magnetic properties. Phase analysis, crystalline structures and crystallite sizes of the nanocomposite were revealed using the X-ray diffraction. Nanosize, globular shape morphologies were revealed using SEM and TEM bright field images. The optical energy band-gap from the optical absorbance spectra was estimated to be 2.22 eV. The electrochemical properties of the composite were observed by cyclic voltammetry studies. The symmetric behavior of the voltammetry plots indicates that the nanocomposite is a favorable candidate used for the fast redox reactions with higher specific capacitance. The vibrating sample magnetometer studies confirm the paramagnetic behavior at room temperature. Electronic structures of the composite reveal the half-metallicity and magnetic behavior of Pd/Mn(Mn1·36Pd0.64)O4 structure.

Effect of divalent metal ions substitution on structural and magnetic properties of Li0.25Mn0.5-xMxFe2.25O4 (M = Co2+, Ni2+, Cu2+) spinel ferrites

In the existing study, substitution of different divalent metal ions in Li0.25Mn0.5-xMxFe2.25O4 (where, M = Co2+, Ni2+, Cu2+; x = 0.0, 0.1, 0.3 and 0.5) was performed to improve the magnetic properties. Their structural and magnetic features were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). XRD analysis proved the presence of single phase cubic spinel structure in all prepared compositions. The lattice parameter decreased linearly with increasing doping concentrations. The crystallite size values vary from 60 to 101 nm. VSM studies revealed that saturation magnetization values of Li0.25Mn0.5-xMxFe2.25O4 were strongly affected by different metal ions substitutions, which is credited to the cationic arrangement on the lattice sites. The change in the magnetization with metal substitution was discussed by using Neél's two-sublattice model. Among the three investigated series, Li0.25Mn0.5-xCoxFe2.25O4 ferrite revealed a synergistic effect in improving the magnetic properties making it suitable for applications in microwave devices and magnetic recording media. The initial permeability μi was measured at elevated temperatures from 300 up to 890 K. The composition Li0.25Mn0.4Ni0.1Fe2.25O4 gave the highest value of initial permeability, indicating the material potential utility in TV deflection yokes. Curie temperature increased with the replacement of manganese ions by different metal ions. In general, the replacement of different divalent transition metal ions plays an important role in changing the structural and magnetic properties of Li0.25Mn0.5Fe2.25O4 ferrites.

Synthesis, characterization and investigation of photocatalytic activity of ZnMnO3/Fe3O4 nanocomposite for degradation of dye Congo red under visible light irradiation

ZnMnO3/Fe3O4 magnetic nanocomposites were fabricated via facile co-precipitation route and were calcined at 400 °C for 3 h. Synthesis of ZnMnO3/Fe3O4 magnetic nanocomposites were optimized by different weight percentages. Then, the as-synthesized sample was characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), photoluminescence(PL), vibrating Sample Magnetometer (VSM), EDAX (Energy dispersive X-ray analysis), diffuse reflectance UV–Vis spectroscopy (DRS),ultraviolet–visible (UV–Vis) spectrometry, Bruner-Emmett-Teller (BET), transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM). Based on the results, elemental analyses of the samples were similar to those expected from the initial concentrations of the solutions used during synthesis. The x-ray diffraction pattern revealed that ZnMnO3/Fe3O4 has a cubic structure and average particle size of the catalyst was found 27.43 nm. In addition, Fourier transform infrared spectra could confirm the presence of hydroxyl group and Fe–O bond vibration in the catalyst. Further, the superparamagnetic behavior of the synthesized nanocomposite at room temperature was confirmed by VSM studies. Furthermore, the photocatalytic performance of ZnMnO3/Fe3O4 samples were evaluated based on the removal of Congo red (CR) in aqueous solution in 60 min of under visible light irradiation. The experiment demonstrated that 0.10 g of ZnMnO3/Fe3O4 nanocomposites can degrade (98.17%) 50 mg l−1 of Congo red (CR) solution. The mechanistic study using scavengers propose that the superoxide (O2·−) is the most reactive species involved in the photodegradation of organic dyes. The photocatalytic degradation of Congo red conformed the pseudo-first-order kinetic model and the rate constant achieved for 0.10 g l−1 of ZnMnO3/Fe3O4 was (k = 0.0384 min−1). Finally, the effect of reaction time, pH, and loading of ZnMnO3/Fe3O4 on degrading Congo red was studied. The synthesized ZnMnO3/Fe3O4 nanocomposite can be potentially applied as a magnetically separable photocatalyst to deal with water pollution problems.

Influence of Mn dopant on the crystallite size, optical and magnetic behaviour of CoFe2O4 magnetic nanoparticles

Cubic spinel structured Co1-xMnxFe2O4 (x = 0, 0.25, 0.5, 0.75 & 1.0) nanoparticles were successfully synthesized by the chemical precipitation method. Increase in Mn content shows a significant reduction on the crystallite size from 16.7 to 10.19 nm. FTIR vibrational bonds between 464 and 585 cm−1 confirm the interaction of metal-oxygen at tetrahedral and octahedral sites, a de-notified vibrations stretch. UV–visible diffuse reflectance spectrum indicates that Co–Mn ferrite is a direct bandgap material with bandgap ranges from 3.84 to 4.02 eV. The red-emission of the samples was confirmed form the peak at 680 nm. Formation of single domain cobalt ferrite nanoparticles of size ~38–72 nm was confirmed by TEM which exhibited morphological transition from nanobar to nanoparticles. Inductively coupled plasma emission - optical emission spectrometer result confirmed the homogeneous mixing of Co, Mn, Fe, and O atoms. The vibrating sample magnetometer study confirmed that Mn concentration favours the magnetic transition from ferromagnetism to superparamagnetism. Saturation magnetization gets reduced from 34.20 to 0.5 emu/g and the and coercivity gets reduced from 0.1112 to 0.0328 T. The X-band electron paramagnetic resonance spectrum recorded at room temperature imparts the increase of superexchange interaction with the increase in manganese concentration.