Synthesis Of Spinel Research Articles

Synthesis of nanoscale spinel aluminates powder and studies of their optical and structural properties

In this research, Manganese aluminate (MA), Nickel aluminate (NA), and Zinc aluminate (ZA) nanocrystallites were synthesized using the combustion method at a temperature of 1173 K. This technique was selected for its effectiveness in producing nanocrystalline materials with high purity and precise compositional control. The synthesized nanocrystallites underwent extensive characterization to understand their structural and optical properties. Techniques such as UV–visible spectrophotometry (UV–vis), Fourier-transform infrared spectroscopy (FT-IR), and x-ray diffraction (XRD) were utilized to examine the impact of different cations (Mn2+, Ni2+, Zn2+) on the optical bandgap, binding energy, and crystallographic parameters of the materials. The optical bandgap values (Eg), determined using Tauc’s formula, were 4.121 eV for manganese aluminate, 3.819 eV for nickel aluminate, and 3.771 eV for zinc aluminate. FT-IR spectroscopy identified fundamental absorption peaks within the range of 450 to 750 cm−1, confirming the formation of aluminate spinel structures. XRD analysis confirmed the presence of a cubic spinel-type structure in all three prepared samples. The results revealed that the average crystallite sizes ranged from 23.890 nm to 45.100 nm, cell volumes varied between 521.47 Å3 and 548.68 Å3, lattice constants spanned from 8.258 Å to 8.049 Å, and inter-planar spacing ranged from 2.4268 nm to 2.4532 nm. These variations were observed as the cation transitioned from nickel to manganese passing through zinc element. Additionally, Rietveld refinements were performed to further analyze and refine the crystal structures based on XRD data. This comprehensive study aimed to elucidate the relationship between the synthesis conditions and the resultant properties of the nanocrystallites, providing insights into their potential applications in fields such as optoelectronics and photocatalysis.

Synthesis of MnFe2O4 Spinel on Rusted Q235 Steel Surface and Its Corrosion Resistance Properties.

Corrosion of steel is an issue that cannot be ignored in contemporary society. Due to large-scale corrosion, it is urgent to develop a surface treatment process that enhances the corrosion resistance of steel, allowing for application in various scenarios as needed. This study aims to investigate a novel surface treatment process to extend the service life of corroded Q235 steel, reduce its sensitivity to corrosion, and enable its use in multiple environments. This study employs the sol-gel method, using manganese nitrate solutions of varying concentrations to treat the surface of Q235 steel after different electrolysis times. The optimal conditions for precursor preparation were found to be a Mn2+ concentration of 0.1 mol/L and an electrolysis time of 2 h. Electrochemical tests using NaCl solutions of different concentrations revealed a significant reduction in the corrosion current for the composite coating based on Q235 steel treated with this method in NaCl solutions with wt.% = 1, 2, 3, 4, 5. Furthermore, the resistance to corrosion was strongest in the NaCl solution with a concentration of 1 wt.% where the corrosion current decreased from 24.8 µA/cm2 to 6.79 µA/cm2. Additionally, the coating was found to be diffusion-controlled in the early stages of the corrosion process and charge transfer-controlled in the later stages. The MnFe2O4 spinel coating demonstrated the greatest enhancement in corrosion resistance in the wt.% = 1 NaCl solution.

Synthesis of spinel МgМn2О4 nanoparticles by the co-precipitation method in an ultrasonic field

Nanoparticles of spinel MgMn2O4 were synthesized using the co-precipitation method in an ultrasonic field. It was established that at a calcination temperature of 200 °C, all peaks on the diffractogram of the synthesized material corresponded to spinel MgMn2O4 with a cubic lattice, pronounced crystallinity, and the absence of other phases. As the calcination temperature increased, the formation of new phases – Mn oxides (respectively, Mn5O8 and Mn2O3) – was recorded. The average size of MgMn2O4 particles was calculated from the diffraction peaks using the Debye-Scherrer equation and equated to 24.4 nm at a calcination temperature of 200 °C. An increase in the specific power of the ultrasonic processing of the reaction medium revealed a natural increase in the proportion of the amorphous phase and a decrease in the average size of MgMn2O4 particles.

Formation of carbon with a diamond-like lattice during the production of spinel MgAl2O4 by a combustion synthesis

Magnesium aluminate spinel (MAS) containing a carbon impurity was prepared by self-propagating high-temperature synthesis (SHS). Periclase MgO, alumina Al2O3, fuel Al powder, 2 wt% boron, and oxidizer Mg(NO3)2·6H2O were used as starting reagents for MAS synthesis. The phase composition of original boron and synthesized products, the structure and surface morphology of the samples were investigated. EDS analysis and elemental mapping confirmed that the impurity detected as crystals formed during the synthesis was carbon. IR spectroscopy showed that the carbon detected in the synthesized product has a diamond-like lattice similar to that of detonation diamonds. The analysis of gases evolved during combustion was performed. A proton‑boron reaction is shown to take place during fast self-propagating high-temperature synthesis of spinel. The probable mechanisms of carbon formation in the synthesis products are proposed using the experimental data.

Synthesis of spinel (Mg0.2Co0.2Ni0.2Cu0.2Zn0.2)Fe2O4 in seconds for lithium-ion battery anodes

A spinel high-entropy oxide was synthesized in 5 seconds with conversion and alloying hybrid reaction kinetics for Li-ion storage.

Research progress of Co-based spinel oxide materials for direct methanol fuel cells

With decades of research, both the synthesis and applications of spinels have achieved greatly increased development. The preparation, regulation strategies, and their application in MOR of Co based spinels are reviewed in this paper.

Microwave-assisted exploration of the electron configuration-dependent electrocatalytic urea oxidation activity of 2D porous NiCo2O4 spinel

Urea holds promise as an alternative water-oxidation substrate in electrolytic cells. High-valence nickel-based spinel, especially after heteroatom doping, excels in urea oxidation reactions (UOR). However, traditional spinel synthesis methods with prolonged high-temperature reactions lack kinetic precision, hindering the balance between controlled doping and highly active two-dimensional (2D) porous structures design. This significantly impedes the identification of electron configuration-dependent active sites in doped 2D nickel-based spinels. Herein, we present a microwave shock method for the preparation of 2D porous NiCo2O4 spinel. Utilizing the transient on-off property of microwave pulses for precise heteroatom doping and 2D porous structural design, non-metal doping (boron, phosphorus, and sulfur) with distinct extranuclear electron disparities serves as straightforward examples for investigation. Precise tuning of lattice parameter reveals the impact of covalent bond strength on NiCo2O4 structural stability. The introduced defect levels induce unpaired d-electrons in transition metals, enhancing the adsorption of electron-donating amino groups in urea molecules. Simultaneously, Bode plots confirm the impact mechanism of rapid electron migration caused by reduced band gaps on UOR activity. The prepared phosphorus-doped 2D porous NiCo2O4, with optimal electron configuration control, outperforms most reported spinels. This controlled modification strategy advances understanding theoretical structure-activity mechanisms of high-performance 2D spinels in UOR.

Steam reforming of methane over nickel-aluminum spinel-derived catalyst

Despite steam reforming of methane (SRM) has been the dominant way to produce hydrogen in industrial owing to its large hydrogen production capacity, easy accessibility of feedstocks and relative low cost, the development of high-efficient catalysts is still of great significance. In this work, we report the synthesis, characterizations and evaluation of Nickel-aluminum spinel (NiAl2O4) catalyst in SRM reaction. Compared with Ni/γ-Al2O3 catalyst prepared by impregnation, NiAl2O4 presents higher methane conversion. Virous of characterizations exhibit NiAl2O4 possesses higher distribution of Ni and smaller Ni nanoparticle size, which is one of advantages for its high activity. Another vital reason is the generation of oxygen vacancies in spinel during the reduction, which is beneficial for the activation of water. Moreover, NiAl2O4 catalyst shows extremely stability without obvious deactivation in 160 h. This study illustrates that the construction of catalyst with high activity and stability via NiAl2O4 spinel and reals its high activity origination.

Solid-State Reaction Synthesis of MgAl2O4 Spinel from MgO-Al2O3 Composite Particles Prepared via Electrostatic Adsorption.

This paper presents the formation of magnesium aluminate spinel using composite particles prepared via electrostatic adsorption (ESA). Scanning electron microscopy (SEM) images confirmed the presence of Al2O3-MgO composite particles. A mixture of Al2O3 and MgO raw materials was also prepared by using the conventional bead-milling method for comparison. The samples sintered at elevated temperatures were characterized through X-ray diffraction, SEM, and relative density measurements. Additionally, the lattice parameter and strain of the samples were determined using the Nelson-Riley function and the Williamson-Hall equation. A pure spinel phase formed in the ESA-derived sample sintered at 1400 °C, while the MgO structure remained in the conventionally prepared sample sintered at 1600 °C. The densities of samples sintered at 1450 °C or higher exceeded 90%. The lattice strain of the prepared samples was inversely proportional to the sintering temperature, attributed to the formation of large grains at higher temperatures. However, the sample sintered at 1600 °C for 8 h exhibited the highest strain of 0.0074 because the crystals grew in a certain direction.

Calcium zirconate–based refractory with improved thermal shock damage resistance from Egyptian dolomite and zirconia through in situ spinel synthesis

Calcium zirconate–based refractory with improved thermal shock damage resistance from Egyptian dolomite and zirconia through in situ spinel synthesis

Synthesis and characterization of CoMn2O4 spinel onto flexible stainless-steel mesh for supercapacitor application

CoMn2O4 spinel was synthesized on stainless steel mesh through a hydrothermal process, controlling the reaction time (6 h, 12 h, 18 h, and 24 h). Characterization techniques included XRD, ATR-FTIR, XPS, and SEM-EDS. The 24-h reaction time led to CoMn2O4 spinel with the desired structure, stoichiometry, and good crystallinity. The sample exhibited a tetragonal structure, with Co–O and Mn–O vibrational bands, and manganese (Mn3+) and cobalt (Co2+) metal oxides on the surface. It had a sheet-like shape with an average particle size of 1.92 ± 0.28 μm. Electrochemical tests showed high CV-specific capacitance of 1014.15 F g−1 at 1 mV s−1 and 764.84 F g−1 at 5 mV s−1, aligned with GCD-specific capacitance at 5 A g−1 (724.61 F g−1) and a charge-transfer resistance of 7.71 Ω. The synthesized electrode holds promise for practical energy storage devices, namely for supercapacitor applications.

Synthesis of MgAl2O4 Spinel in a Thermal Plasma

Synthesis of MgAl2O4 Spinel in a Thermal Plasma

Synthesis of cobalt aluminates by using the peel extracts of Citrus family species

Synthesis of cobalt aluminate was achieved by using the peel extracts of Citrus family species. The peel extracts of lemon, orange and mandarin were used as capping agent in experimental step. These peels were extracted through varied solvents including water, ethanol and methanol. In this regard, the efficacies of the peel type and the extraction liquid were surveyed in the study, using a co-precipitation technique in the synthesis of CoAl2O4 spinel. Samples compared in different parameters were subjected to a range of analyses consisting of colorimetry, X-Ray Diffraction, Scanning Electron Microscope and thermal examinations. The minimum b* value was reached as –14.23 in the sample with a capping agent provided by the orange peel extract, extraction liquid of which is water. The results denoted successful crystal structure scores and single-phase CoAl2O4 formation as well as the occurrence of a double-phase configuration. The highest XRD score of 83 was obtained for CoAl2O4. Considering SEM results, the lowest and highest particle size distributions were found between 100–150 nm and 350–800 nm, respectively. In the research, cobalt aluminate synthesis was carried out by means of modifying agents prepared with the peels of Citrus family species using different solvents.

Facile synthesis of CuCo2O4 spinel with rGO nanocomposite via hydrothermal approach for solid state supercapacitor application

Spinel oxide nanomaterial based on pseudocapacitor electrodes is a superior remedy for the present energy problem. In this study, CuCo2O4 and reduced graphene oxide (rGO) are mixed utilizing a clean hydrothermal strategy. The characteristics of synthesized electrocatalysts were examined by employing microscopic and spectroscopic techniques. Galvanostatic charge-discharge techniques (GCD), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA) were used to analyze the electrocatalytic behavior of all synthesized materials. The electrochemical analysis showed that the incorporation of rGO rises the discharge duration interval resultant enhances the specific capacitance (Cs) and improves the overall stable behavior of the CuCo2O4 electrocatalytic materials. At 2.0 A g−1, the electrochemical findings of spinel/rGO nanohybrid show Cs of 1372.93 F g−1, energy density (Ed) of 70.02 Wh Kg−1 and power density (Pd) of 606 W Kg−1 at 2 A g−1. The nanohybrid showed 96.35 % capacitance retention over 5000th cycles and remained stable for 40 h. However, adjustments to the electrical and structural arrangement, morphology, or doping technique improved the capacitive activity of the produced electrode.

Thermal synthesis of NiMn2O4 spinel employing Mn oxide ores as starting material

Thermal synthesis of NiMn2O4 spinel employing Mn oxide ores as starting material

Insights into the interface of NiCo2O4 spinel /LaCoO3 perovskite nano-composite for CO and soot oxidation

In the quest for the development of thermally stable, highly active and low-cost catalysts for use in catalyzed diesel particulate filter, nano-composites are new areas of research. Therefore, we reported the easy synthesis of spinel NiCo2O4/perovskite LaCoO3 nano-composite, and its individual oxides NiCo2O4 and LaCoO3 for comparison. The detailed insights into the physio-chemical characteristics of formed NiCo2O4/ LaCoO3 nano-composite were done based on various characterization analysis such as X-ray diffraction (XRD), Fourier transform infrared (FT-IR), N2 physiosorption, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDX), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The characterization analysis of NiCo2O4/LaCoO3 revealed the successful formation of a chemical interface possessing strong interfacial interaction, resulting in desirable physicochemical characteristics such as small crystallite size, abundant mesoporosity, high specific surface area and activation of surface lattice oxygen. Owing to the desirable characteristics, the activity results over NiCo2O4/LaCoO3 nano-composite showed the excellent CO oxidation performance and high soot oxidation activity, recyclability and thermal stability. This work mainly attempts to emphasize the effectiveness of the facile, inexpensive and conventionally used precipitation method for the successful formation of highly efficient nano-composites.

Fabrication and characterization of macroporous alumina -nano tetragonal zirconia -nano spinel ceramic composites

In order to protect the environment, waste materials like bagasse have recently been recycled in the production of porous ceramics. For the synthesis of nano tetragonal zirconia (t-ZrO2) and nano spinel (MgAl2O4), a modified co-precipitation method is used. The phase composition, particle size, and surface area of the synthesized nanoparticles were examined using X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM- TEM), and Brunauer-Emmett-Teller (BET) analyses, respectively. To prepare alumina – nano t-ZrO2 –nano spinel macroporous ceramics, nano t-ZrO2 was added from 0 to 30 wt% at the expense of nano spinel to calcined alumina (70 wt%). Bagasse ash (as a pore-forming agent) was added to the mixed compositions in weight percentages ranging from 0 to 15 wt%. All prepared samples were sintered at different temperatures (1350, 1450, and 1450 °C). The influence of nano t-ZrO2, bagasse ash, and sintering temperature on the phase composition, densification parameters, cold crushing strength (CCS), microstructure, and the distribution of pores in sintered samples was looked into. According to the results, the major phases observed in sintered samples are corundum, spinel, tetragonal zirconia, and monoclinic zirconia phase. The cold crushing strength of sintered samples increased with increasing nano tetragonal zirconia additions due to the tetragonal to the monoclinic toughening mechanism of t-zirconia. With increasing bagasse additions, the bulk density decreased from 2.66 g/cm3 to 1.49 g/cm3, while the apparent porosity increased from 30.2% to 56.04%. The microstructures and pore size distribution of the sintered samples show that the prepared porous ceramic samples have high crystallinity, with an average pore size between 2.51 μm and 3.32 μm.

Synthesis of (Cu,Mn,Co)3O4 Spinel: Effects of Citrate-to-Nitrate Ratio on Its Homogeneity and Electrical Properties

The (Cu,Mn,Co)3O4 (CMC) spinel layer is useful in inhibiting Cr vaporization that deteriorates the solid oxide fuel cell performance. The effectiveness of the spinel layer in suppressing volatile Cr species from the metallic interconnects is strongly dependent on layer density, which is influenced by particle size distributions and agglomerations of the spinel powders. Considering that the material properties were influenced by the synthesizing conditions, this study elucidated the influences of citric acid (fuel) on the structure, morphology, and electrical properties of sol–gel derived CMC spinel powders. Dual-phase CMC spinel powders, consisting of cubic CuMnCoO and tetragonal Mn2CoO4, were successfully synthesized at citrate-to-nitrate (CA/MN) ratios of 0.8, 1.0, and 1.2. An undesired CuCo2O4 phase was observed in spinel powders synthesized at a low CA/MN ratio of 0.5. The CA/MN ratio has influenced not only the phase formation of CMC spinel, but also the particle size distributions. The CA/MN ratio of 1.0 yielded the finest CMC spinel with the least agglomerates, which then produced the highest electrical conductivity of 116 Scm−1. Therefore, the CA/MN ratio of 1.0 was recommended for the synthesis of CMC spinel, which can be used in fabricating the protective coating of solid oxide fuel cell interconnects.

Solid-state synthesis of ZnMn2O4 spinel: Sequence of phase transformations, thermal stability, localization and charge state of manganese ions in the intermediate and final reaction products

This paper presents data on the solid-state synthesis of spinel ZnMn2O4, one of the leading promising materials for numerous practical applications. The evolution of the phase composition and charge state of manganese ions during the solid-state synthesis of ZnMn2O4 in air from ZnO and Mn2O3 has been studied. Using differential thermal, thermogravimetric, and X-ray diffraction analysis methods it has been established that, at a temperature of about 700 °C, an insignificant amount of ZnMn2O4 is present in the mixture with the initial oxides. During further heat treatment ZnMn2O4 interacts with Mn2O3 to form the solid solution based on ZnMn2O4. In parallel with this process, in the temperature range of 800–850 °C, ZnMn2O4 reacts with ZnO to form the compound ZnMn4+O3. It has been shown that heat treatment at 880–1180 °C leads to the formation of the final single-phase product – ZnMn2O4. Using diffuse reflectance spectroscopy, XPS, and FT-IR methods, the charge state and localization of Mn ions in the intermediate and final synthesis products have been determined. It has been shown that in the Zn1-xMn2+xMn3+2O4 solid solution Mn2+ ions are localized in the tetrahedral positions and Mn3+ ions in the octahedral positions of the structure. In the final single-phase product, ZnMn2O4, the tetrahedral positions are occupied only by zinc ions, and the octahedral positions are occupied only by Mn3+ ions. It has been established that ZnMn2O4 is stable up to 1300°С. Upon reaching this temperature, ZnMn2O4 decomposes into ZnO and Zn1-хMn2+хMn3+2O4.

Spin-glass behavior and redox catalytic properties of room temperature produced ZnCrMnO4

Recognizing the multifunctional capability of spinels, synthesis, and properties of oxide spinel with an equal concentration of Jahn Teller active Mn 3+ and geometrically frustrated Cr 3+ with non-magnetic Zn 2+ have been explored. ZnCrMnO 4 , resulting from the room temperature oxidation reaction, has an average crystallite size of 16 nm. Nearly 25% of Zn occupies the octahedral sites along with Cr and Mn, as revealed by the successful structural refinement in the Fd-3m space group. Electron microscopic results confirm cubic spinel formation. Raman spectrum shows the disordered nature of the spinel. X-ray photoelectron spectral (XPS) analysis establishes mixed valences of manganese ((III), (IV)) and chromium ((III) and (VI)). ZnCrMnO 4 displays electronic transitions typical of Mn 3+ and Cr 3+ in its UV–Visible diffuse reflectance spectrum. Spin-glass frustration at 26 K, followed by an antiferromagnetic ordering at 10 K, is noticed for the sample from the magnetic measurements. The sample exhibits a surface area of 138 m 2 /g (BET measurements) and catalyzes the oxidation of aromatic alcohols (phenol, benzyl alcohol) and reduction of nitroaromatics efficiently.