Pure Spinel Phase Research Articles

Effects of Bi2O3-V2O5 mixture on microstructure and magnetic properties for Li0.42Zn0.27Ti0.11Mn0.1Fe2.1O4 ferrites sintered at low temperatures

In this study, Bi2O3-V2O5 (BV) mixture was introduced to serve as a kind of sintering aid to assist the preparation of LiZn ferrites. The Li0.42Zn0.27Ti0.11Mn0.1Fe2.1O4 ferrites were successfully synthesized at relatively low temperatures, and all the samples exhibited a pure spinel phase. Meanwhile, the grain growth was significantly promoted, and the average grain size was elevated from 0.92 to 6.58 µm when the addition amount of BV mixture increased from 0.0 to 0.18 wt. %. In regard to the magnetic properties, the saturation induction (Bs) value could reach as high as 319 mT, and the coercivity (Hc) and ferromagnetic resonance linewidth (ΔH) decreased to 153 A/m and 182 Oe, respectively. It is worth noting that the proper addition amount is a key factor for enhancing the properties of ferrites, insufficient or excess BV mixture will deteriorate the properties. Therefore, it is expected that BV mixture can be employed as an effective sintering aid, which will improve the properties of ferrites and promote the development of low temperature co-fired ceramics (LTCC) technology.

Investigation on growth mechanism and gyromagnetic properties of low-sintered Li0.43Zn0.27Ti0.13Fe2.17O4 ferrite doped with Nb2O5 and glass sintering additives

Interest in improving the magnetic properties by co-doping has thrived since it is demonstrated that such co-doping can be used to control the microstructure of ferrites at a low sintering temperature. Usually this process involves grain growth and densification by liquid phase sintering or, in some cases, abnormal growth of grain. Here, we study the growth mechanism of the low-sintered LiZnTi ferrites doped with additions of Nb2O5 and Li2CO3-MgO-ZnO-B2O3-SiO2 (LMZBS) glass through characterization of microstructure and magnetic properties. SEM results show that along with the increase of LMZBS glass contents, the change of ferrite grain presents three different stages. At the initial stage, densification of grain is dominant and grain growth is unconspicuous. Due to the increase of LMZBS glass content, the main process at the second stage is grain growth. At the last stage, however, grain growth starts to be suppressed and pores appear again because of competition between the two additives. Corresponding to each stage, the magnetic parameters of the LiZnTi ferrites, including 4πMs, Hci, Bs, Br/Bs and ΔH, have different trends. Moreover, XRD patterns show that all samples have a pure spinel phase, which means influence of the two additives on crystal structure is negligible. All in all, we obtain a LiZnTi ferrite with uniform and compact microstructure, high saturation flux density (Bs=294.2mT), remanence ratio (Br/Bs=0.87), saturation magnetization (4πMs=3700.1 G) and low ferromagnetic resonance linewidth (ΔH=253) at 900 °C.

Probing electrochemical charge storage of 3D porous hierarchical cobalt oxide decorated rGO in ultra-high-performance supercapacitor

A 3D porous hierarchical Co 3 O 4 -reduced graphene oxide nanosheet (Co 3 O 4 -rGO) heterostructure is synthesized by a facile hydrothermal method . Microstructure analysis confirms the decoration of Co 3 O 4 hierarchical structures with an urchin-like spherical microstructure on rGO nanosheet with an average size of about 50 nm. The structural analysis reveals the formation of phase pure spinel Co 3 O 4 and reduced graphene showing their simultaneous existence in the composite. Raman spectroscopy confirms the successful reduction of graphite oxide to reduced graphene oxide and the effectual interaction between Co 3 O 4 and rGO matrix. The Co 3 O 4 -rGO composite electrode possesses utmost specific capacitance 688 F g −1 , due to effective ion transfer and slight agglomeration of Co 3 O 4 hierarchical structures on the surface of reduced graphene oxide. It is noteworthy that we have demonstrated a flexible solid-state supercapacitor device that exhibits an excellent performance suggesting the possible use of 3D porous hierarchical Co 3 O 4 -rGO composite in supercapacitor devices. Urchin-like spherical Co 3 O 4 decorated on rGO nanosheet delivered high specific energy of 72.6 Wh kg −1 corresponding to a specific capacitance of 688 F g −1 . • Hierarchical urchin-like Co 3 O 4 spherical microstructure decorated on rGO nanosheets is successfully synthesized. • The composite exhibits high capacitance of 688 F g −1 rate with excellent long-term stability. • Composite shows capacitance retention after 10,000 cycles with superb cycling stability (96%).

Molten salt synthesis of LiMn 1 . 2 Ni 0 . 3 Cr 0 . 1 Co 0 . 15 Al 0 . 23 La 0 . 02 O 4 as a positive electrode for lithium‐ion batteries

The molten salt synthesis method became an excellent synthesis technique to elaborate nanomaterials because of its meritorious advantages including low cost, easy to scale up, simple to operate, and environmental friendliness. For this reason, the compound LiMn1.2Ni0.3Cr0.1Co0.15Al0.23La0.02O4 was synthesized for the first time by molten salt method using NaCl as the salt and a nonstandard manganese source with metallurgical grade. The obtained cathode material was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transformer infra-red (FT-IR), and electrochemical characterization. XRD and FT-IR results confirm the stability and formation of pure spinel phase without any impurities. TEM images showed that the spinel synthesized phase consists of 77 to 135 nm-sized polyhedral nanoparticles. The cyclic voltammogram results showed that the synthesized spinel cathode material exhibits two-main redox peaks at 4.06/3.9 V and 3.1/2.8 V vs Li+/Li, which indicate the possibility of insertion of extra lithium in the spinel structure. Galvanostatic charge-discharge studies were also carried out showed that the prepared spinel material has two discharge plateaus in the potential window of 1.5 to 5 V and a discharge capacity of 179 mAh g−1 at 0.1 C, which is higher than the theoretical value which confirms the insertion of extra lithium in the spinel structure and enhance the capacity of the cathode material. The electrochemical impedance spectroscopy was performed, and the Li-ion diffusion coefficient was also calculated.

Preparation of submicron-sized ZnFe2-xCrxO4 (x = 0.4, 0.8) via a two-step method and evaluation of the corresponding ceramic inks

In this work, submicron-sized ZnFe2-xCrxO4 (x = 0.4, 0.8) pigments were synthesized by a combustion assisted two-step method. The samples and corresponding ceramic inks are investigated by XRD, SEM, TEM, colorimeter, and laser particle size analyzer. The grindability of the pigments and the printing performance (rheological properties, surface tension, filterability and storage stability) of the inks are evaluated. Our research reveals that although the calcination temperature in the present method is 300 °C lower than the conventional solid-state reaction route, the as-prepared samples belong to a pure spinel phase and present highly saturated reddish-brown tone. Compared to the samples prepared from solid-state reaction route, the synthesized submicron-sized pigments exhibit superior grindability. The corresponding ceramic inks present excellent coloring ability, filterability and storage stability. Our work confirms that the submicron-sized ZnFe2-xCrxO4 pigments synthesized by the combustion assisted two-step method are quite suitable for ZnFe2-xCrxO4-based reddish-brown ceramic inks.

Study of magnetic and dielectric properties of ZnFe2O4/CoCr2O4 nanocomposites produced using sol-gel and hydrothermal processes

In this work, zinc ferrite (ZnFe2O4) and cobalt chromite (CoCr2O4) nanoparticles were synthesized using sol-gel process and hydrothermal method, respectively. The two different materials were mixed by physical means such that the final ratio (by weight) of the resulting nanocomposites (ZnFe2O4:CoCr2O4, abbreviated as ZF:CC) were 3ZF-CC, ZF-CC and ZF-3CC. The x-ray diffraction patterns of the ZnFe2O4 and CoCr2O4 nanoparticles confirmed the formation of the spinel structure, whereas the average crystallite size values computed using the Scherrer equation were found to be 43 and 57 nm, respectively. Scanning electron microscope (SEM) examination of the nanocomposites confirmed the nonspherical shape of the nanoparticles, homogenous dispersion, and larger grain size. The phase pure spinel structures of ZnFe2O4 and CoCr2O4 was confirmed from the fourier transform infrared spectroscopy (FTIR) analysis. Also, the composites formation did not influence any change in the functional groups. The dielectric properties, determined using LCR meter, exhibited non-repetitive behavior for the ZF-CC composite. The significant increase in the dielectric constant value was observed as the Fe2+↔Fe3+ and Cr2+↔Cr3+ transition due to electron transfer plays vital role in low frequency region, Also, explained by Maxwell-Wagner model. Moreover, the variation in experimental magnetic moments of ZF, CC and their nanocomposites (ZF-3CC, ZF-CC,3ZF-CC) were studied. VSM results revealed the change in behavior of magnetic nature of materials appreciably from pristine as magnetization was increasing and coercivity was decreasing with CC component and finally an optimized magnetic parameter values (Ms =51.20 emu/g and Hc =200 Oe) at ZF-CC were obtained.

Evolution of structure and magnetic properties in MnZn ferrite-silica nanocomposites fabricated by sol–gel method

We explore the influence of the silica matrix on size, spinel phase stability, and magnetic properties of MnZn ferrite. For this purpose, Mn0.6Zn0.4Fe2O4 (MZF) nanoparticles (NPs) dispersed in silica (SiO2) matrix [MZF1−x/(SiO2)x x = 0, 10, 30%] synthesized by one-pot sol–gel process. The evolution of a pure spinel phase is apparent from the as-prepared (AP) MZF/SiO2 (30%) amorphous state on annealing in the temperature range 600–900 °C in air, whereas the AP free-standing MZF NPs exhibit a secondary phase of α-Fe2O3 along with spinel structure in this temperature range. The crystallite size is 5 ± 1 nm for a 600 °C annealed sample and increases to 10 ± 1 nm for a 900 °C annealed sample. From the detailed analysis of the temperature and magnetic field-dependent magnetization data, it is found that the AP sample exhibits weak magnetic behavior. However, annealed samples exhibit a maximum in zero-field-cooled magnetization at a certain temperature (TP), which increases with the increase of annealing temperature. The M–H curves above TP indicate the presence of superparamagnetic (SPM)-like behavior. From the present study, we show that the phase stability and magnetic properties of MZF/SiO2 composites have improved compared to bare MZF NPs.

Structural, magnetic and electrical properties of electroactive-superparamagnetic PVDF-Sn0.2Fe2.8O4 nanocomposite films

PVDF films embedded with magnetic Sn0.2Fe2.8O4 nanoparticles at selected volume percentages (≤20%) were prepared by using a quick and cost-efficient method of solution casting. Using a facile technique of alternate stirring and ultrasonication of the dispersion, the less investigated electroactive γ-PVDF phase was predominantly obtained in the pure polymer as well as loaded films. X-ray diffraction with Rietveld analysis and TEM imaging established the pure spinel phase and size of nanoparticles, respectively. Additionally, FTIR spectroscopy evidenced the γ-phase crystallinity of all the nanocomposite films with traces of α-PVDF in ≥5 vol% films. The films exhibited superparamagnetic character; the saturation magnetization increased with Sn0.2Fe2.8O4 content (from ≈0.1 to 7 emu/g) with nearly constant coercivity (≈16 Oe). The dielectric constant varied between 1 and 8 with low tangent loss (≤0.11) in the 100 Hz–1 MHz frequency range. These nanocomposite films hold promise in areas like micro-electronics, interlayer applications, magnetic sensors, actuators and microwave devices.

Investigating the structural, magnetic, magnetocaloric and critical behavior of Mg0.35Zn0.65Fe2O4 ferrite

In this study, we successfully prepared the Mg0.35Zn0.65Fe2O4 ferrite sample via standard solid-phase reaction and comprehensive studied its structure, magnetism, magnetocaloric effect and critical behavior. The XRD data refined by Rietveld technology confirms that the sample had a pure phase spinel structure. We conducted a magnetic study on the sample using SQUID and indicated that the sample’ ferromagnetic curie temperature Tc = 295 K, the paramagnetic curie temperature TP = 330 K, and the saturation magnetization can reach 125.41emu/g at an ultra-low temperature of 5 K. We tested the initial magnetization curve near the phase transition temperature (Tc) from ferromagnetic (FM) to paramagnetic states (PM) and produced an Arrott plot that confirmed the presence of a secondary phase transition. The sample’ maximum magnetic entropy change |ΔSMmax| was 1.642 J/kg K and relative cooling power RCP was 185.2 J/kg in the external magnetic field H = 50 kOe. The critical parameter β, γ, δ, and TP were calculated using a Modified Arrott plot (MAP), Kouvel-Fisher (KF) plot and critical isotherm (CI) methods to study the type of magnetic order in the ferromagnetic state that corresponded to the magnetic state equation and mean field model. By analyzing the critical parameters, we obtained the ferromagnetic exchange integral constant J(r) ~ r−4.8498, which was between the 3D Heisenberg model and mean field models and very close to the mean field model, confirming that the long-range and short-range ferromagnetic orderly interactions coexisted with interaction phases and the long-range ferromagnetic orderly interaction dominates.

Annealing temperature on the microstructure and magnetic properties of magnesium–cobalt ferrite prepared by sol-gel self-propagating method

In this paper, sol-gel self-propagation is used as the experimental method, and glucose is used as the complexing agent to prepare magnesium–cobalt ferrite (Mg0.1Co0.9FeO4). In the experiment, the annealing temperature of the sample is changed to study the annealing temperature on the ferrite. The influence of the microstructure and magnetic properties. In order to explore the samples, (X-ray diffractometer) XRD, (Fourier infrared spectrometer) FTIR, (scanning electron microscope) SEM and (vibrating sample magnetometer) VSM are usually used to characterize the sample. The characterization results of the samples are analyzed to prove the changes in the microstructure and magnetic properties. There are several obvious diffraction peaks in the XRD diffraction patterns of the five samples. Analysis of the positions of the diffraction peaks can prove that the prepared samples have a pure phase spinel structure. In the Fourier infrared spectroscopy, there is an obvious absorption peak around 580 cm−1. The presence of this absorption peak can also prove that the sample has a spinel structure. The morphology of the sample in the SEM photograph of the sample is round or elliptical, and the particle distribution is obvious, and the size is 100 ~ 200 nm. Vsm tested the magnetic properties of the samples. On the hysteresis loop of each sample, can see that the saturation magnetization and the residual magnetization of the sample reached the maximum when the annealing temperature was 500 °C. When the annealing temperature was 600 °C the coercive force and magnetic susceptibility of the sample reached maximum.

Insightful acetone gas sensing behaviour of Ce substituted MgFe2O4 spinel nano-ferrites

MgCexFe2-xO4 (0 ≤ x ≤ 0.2) nanoparticles have been produced by the glyco-thermal technique and characterized by X-ray diffraction, electron microscopy, X-ray photoelectron spectroscopy, Mössbauer spectroscopy and gas sensing analyses. The X-ray diffraction results indicated that a pure cubic spinel phase was formed for samples having a low concentration of Ce, but the high Ce doping (x = 0.2) of magnesium ferrite resulted in the formation of secondary phases. The crystallite size of the compounds ranged from 2.2 nm to 15.3 nm. The 57Fe Mössbauer spectra showed transformation from an ordered to a paramagnetic spin state with an increase in Ce concentration. Gas sensors fabricated from the spinel ferrites were tested towards various organic compound vapours (acetone, methanol, p-xylene, ethylbenzene, toluene, and benzene) at an operating temperature of 225 °C. The MgCe0.2Fe1.8O4 nanoferrite proved to possess quality sensor characteristics of high sensitivity and selectivity to acetone vapour, with a response of over 500@100 ppm concentration as well as reproducibility, reversibility, and stability of over 120 days. This sensor not only displayed high responses, but could also maintain them over 1, 3, 5, 10, 20, and 30 min of acetone exposure time. The sensor was resilient and sensitive to an oxygen reduced, inert ambient environment. Under relative humidity, the response was reduced, but stable, due to physisorbed water molecules.

An investigation on the N2O decomposition activity of MnxCo1−xCo2O4 nanorods prepared by the thermal decomposition of their oxalate precursors

This investigation aimed to develop a series of new spinel-oxide catalysts with the general formula MnxCo1−xCo2O4 (0.0≤x≤1.0) and testing their activity towards N2O direct decomposition. These catalysts have been prepared by the microwave-assisted co-precipitation method and the subsequent calcination at 500°C. Characterization results revealed that the utilized preparation protocol has led to the development of pure spinel phases with nanorods morphology. N2O decomposition experiments indicated that the prepared catalysts were active and the best performance was exhibited by Mn0.75Co0.25Co2O4 catalyst. The activity of the Mn0.75Co0.25Co2O4 was enhanced by doping with K-ions at optimal concentration (nK/(nCo+nMn)=0.025). The co-existence of some contaminants (O2, NO, H2O vapor) in the reactor feed revealed different inhibitory levels on the performance of the K0.025Mn0.75Co0.25Co2O4 catalyst. The inhibitory order was O2<H2O<NO<O2+H2O<O2+H2O+NO.

Dielectric, impedance, and modulus spectroscopic studies of lanthanum-doped nickel spinel ferrites NiLaxFe2-xO4 nanoparticles

A series of lanthanum (La)-doped nickel (Ni) ferrites NiLaxFe2-xO4 with doping concentrations (x = 0.0, 0.01, 0.02, 0.03, 0.04, and 0.05) is synthesized via a sol–gel auto-combustion method. Structural properties are determined with the help of X-ray diffraction (XRD). The effect of La doping on dielectric properties of Ni ferrites is discussed. XRD analysis confirms the existence of pure FCC spinel phase, and no impurity phase was detected. The lattice constant decreases initially due to strain produced by La3+ ions replacement. At higher doping concentrations, the lattice constant increases due to the large ionic radius of La3+ as compared to Fe3+. Tangent loss (tanδ), dielectric constant, and dielectric loss values are determined in the 1 MHz to 3 GHz frequency range, and explained by the Maxwell–Wagner model. A persistent behavior of dielectric loss and dielectric constant was found in the mid microwave frequency region. The most stable behavior of the dielectric constant (e′) and dielectric loss (e″) in the high-frequency region is found with (x = 0.04). Ac conductivity is also discussed in the 1 MHz to 3 GHz region, and is found to be impacted by grain and grain boundary resistive behavior at low and high frequencies. Cole–Cole plots of different samples, corresponding to different doping concentrations, are used to describe the conduction phenomena. The stable response of dielectric constant (e′) and dielectric loss (e″) in the mid microwave frequency region makes NiLaxFe2-xO4 nanoparticles a potential candidate for microwave devices.

Effect of Calcination Temperature on the Behavior of the Agglomerated $$\text{Co}_{3}\text{O}_{4}$$ Nanoparticles Obtained Through the Sol–Gel Method

Agglomerates of $$\text{Co}_{3}\text{O}_{4}$$ were obtained using the sol–gel method for the synthesis with subsequent calcination of the samples up to 550 °C. Through X-rays it was observed that the samples presented the pure spinel phase with a crystallite size between 33.73 and 41.45 nm. In the thermogravimetric measurement from 262 °C high structural stability is presented with phase change at 917 °C. As the temperature increases, the particles increase in size, observing agglomerated nanometer particles that increase with temperature (3.5–3.8 μm). The 683 cm $$^{-1}$$ Raman mode for 550 °C clearly presents an shifted compared to the other samples. The band gap for the samples under study varied with the temperature change of 1.77–1.81 eV. The FWHM decreases at a higher temperature, this confirms the larger crystallite size and the higher degree of sintering.

Sol-Gel Synthesis of Nanocrystalline Mesoporous Li4Ti5O12 Thin-Films as Anodes for Li-Ion Microbatteries.

The development of anodes based on Li4Ti5O12 (LTO) for lithium ion batteries has become very important in recent years on the basis that it allows a long service life (stability in charge-discharge cycling) and safety improvements. The processing of this material in the form of thin film allows for greater control of its characteristics and an improvement of its disadvantages, namely reduced electrical conductivity and low diffusion of lithium ions. In this work, we try to limit these disadvantages through the synthesis of a mesostructured carbon-doped Li4Ti5O12 thin-film with a pure spinel phase using a combination of a block-copolymer template and in situ synthesis of Li-Ti double alkoxide. Structural and electrochemical characterization has been carried out to determine the best conditions (temperature, time, atmosphere) for the thermal treatment of the material to reach a compromise between crystallinity and porosity distribution (pore size, pore volume, and interconnectivity).

Annealing temperature dependent structural and electrical properties of (Mn,Ni,Co)3O4 thin films

Here, we demonstrated that polycrystalline (Mn,Ni,Co)3O4 films with a high negative temperature coefficient of resistance (NTCR) behavior can be achieved at low annealing temperatures (≤400 °C) via a liquid flow deposition method. The processing conditions applied to obtain the high-quality films were investigated with focus on the flow rate of the oxidizing agent (H2O2) and annealing temperature (Ta). The introduction of an appropriate amount of H2O2 solution into the deposition system led to the partial oxidation of Me2+ ions (Me = Mn, Ni and Co) to Me3+ which subsequently adsorbed to the films, with only little effect on the film surface quality. The pre-existing Mn3+ ions enabled the possibility of reducing the final annealing temperature to 300 °C for the film crystallization with a pure cubic spinel phase. We also studied the dependence of the electrical properties on the Ta in the range of 285–400 °C. It was found that the films were highly conductive and showed a typical NTCR characteristic at annealing temperatures of 300 °C and above. Notably, at Ta ≥ 350 °C, the films exhibited an absolute temperature coefficient of resistance (TCR) exceeding 2.43% K−1 together with a moderate resistivity (ρ) of <3 kΩ cm, indicating their excellent potential for application in infrared detectors. In addition, the films showed good electrical stability with time, as their aging coefficient (ΔR/Ro) varied in a range of 5.9–6.4% after 500 h of aging in air at 150 °C. To the best of our knowledge, there have been no reports on cubic spinel Mn3O4-based thin films at temperatures below 400 °C.

Preparation and electrochemical performance of LiNi0.5Mn1.5O4 spinels with different particle sizes and surface orientations as cathode materials for lithium-ion battery

LiNi0.5Mn1.5O4 hierarchical microspheres composed of primary particles with different sizes and surface orientations are synthesized by high-temperature calcination based on different Ni–Mn oxides pre-sintered at different temperatures. The effects of pre-sintering temperature on the microstructure, morphology, and electrochemical properties of materials are investigated. The results show that pre-sintering temperature has a significant effect on the composition of Ni–Mn oxides, whereas all LiNi0.5Mn1.5O4 products have phase-pure spinel structure. SEM shows that pre-sintering temperature exerts a great influence on the primary particles’ size and surface orientations. With pre-sintering temperature increasing, primary particle size increases gradually, and particle morphology changes from octahedron with {111} surface to truncated polyhedron with extra {100} and/or {110} surfaces. Electrochemical properties are investigated in LiNi0.5Mn1.5O4/Li half-cell and LiNi0.5Mn1.5O4/Li4Ti5O12 full-cell. It is found that the particle size and surface orientation have great influence on the electrochemical performance of LiNi0.5Mn1.5O4. Among them, the LiNi0.5Mn1.5O4 sample synthesized with Ni–Mn oxide pre-sintered at 600 °C shows better rate and cycling performances. This can be ascribed to the synergistic effect of exposed {111} surface and smaller primary particle size, which improves interfacial stability and reduces Li+ ion diffusion distance. The particle size and surface orientation can be tailored to meet different applications of LiNi0.5Mn1.5O4 material.

Structural, magnetic and electrical properties along with antifungal activity & adsorption ability of cobalt doped manganese ferrite nanoparticles synthesized using combustion route

Ultrafine powders of Cobalt doped manganese ferrite with elemental composition Mn1-xCoxFe2O4 (x = 0.2, 0.4, 0.6, 0.8) were synthesized using combustion method. The formation of the pure cubic spinel phase of ferrite structure was confirmed using X-ray diffraction and Fourier transform infrared spectroscopy. Structural parameters such as lattice constant, X-ray density, mass density, porosity, and cell volume were seen to be greatly influenced by cobalt doping. The surface morphology of the nanocrystalline samples was studied using a scanning electron microscope. The particle size distribution was determined using a Transmission electron microscope and nanograins of the samples were found to have dimensions in the range 15 nm–30 nm. It also showed its dependence on the extent of cobalt inclusion. Variation of magnetization and magnetic moment as a function of magnetic field and temperature was investigated using a vibrating sample magnetometer (VSM). The parameters such as saturation magnetization ‘MS’ and inversion temperature TI were seen to depend upon Co+2 concentration. The variation dielectric constant ‘Ԑ’ as a function of frequency was studied. Antifungal activity of these ferrite nanoparticles against Rhizopus fungi was also investigated at room temperature. The antifungal activity was seen to increase with increasing Co+2 content in the manganese ferrite structure and hence cobalt doped manganese ferrites are proposed as a candidate material for industries manufacturing antifungal products. The adsorption studies were also investigated using Methylene dye as the adsorbate.

The role of dysprosium levels in the formation of mixed oxidation states within spinel MnCo2−xDyxO4 nanocrystalline powders

In this work, glycine-aided combustion synthesis of spinel-type MnCo2−xDyxO4 (x = 0.02,0.04 and 0.06 %) nanocrystalline powders is presented. The mechanism involved in the chemical synthesis is briefly discussed. The integrity of the synthesized nanocrystalline powders was investigated and evaluated in correlation with dysprosium levels. Powder X-ray diffraction and Fourier-transform infrared spectroscopy studies confirmed the formation of pure spinel phase with cubic crystal structure. Scanning electron microscopy examinations revealed different agglomerated porous spongy morphologies that varied with different dysprosium levels. The analyses of X-ray photoelectron spectroscopy spectra showed different mixed oxidation states and cationic distributions among the octahedral and tetrahedral sites within the spinel structure as a function of dysprosium levels. It is suggested that MnCo2−xDyxO4 nanocrystalline powders with different morphologies and mixed oxidation states can be tailored via facile synthesis route.

Detailed magnetic characteristics of cobalt ferrite (CoxFe3−xO4) nanoparticles synthesized in the presence of PVP surfactant

While Co ferrite nanoparticles (NPs) have been widely considered for potential applications in magnetic storage, photocatalysts, and hyperthermia, significantly less attention has been paid to explore their detailed magnetic characteristics as a function of the Co content. Herein, a hydrothermal method was successfully used for the preparation of CoxFe3−xO4 (0.5 ≤ x ≤ 2) NPs, employing stable ferric and cobalt salts with PVP surfactant as a capping agent. Hysteresis loop measurements showed maximum coercivity (Hc) and saturation magnetization (Ms) of 982 Oe and 46 emu/g for Co0.5Fe2.5O4 and CoFe2O4 compounds, respectively. Detailed magnetic characteristics of the resulting NPs with different morphologies ranging from nanocubes to dense nanospheres were comprehensively investigated by first-order reversal curve analysis. It was found that CoxFe3−xO4 (0.5 ≤ x < 1) NPs with both spinel and hematite phases comprise noticeable hard and soft phases, whereas superparamagnetic phase starts to dominate magnetic behavior of CoxFe3−xO4 (1 ≤ x ≤ 2) NPs with reduced grain size and pure spinel phase.