Spinel Nickel Research Articles

Effect of cobalt doping on structural parameters, cation distribution and magnetic properties of nickel ferrite nanocrystals

Here, thermal heat treatment method has been used for the synthesis of PVP capped nickel ferrite (NiFe2O4) and cobalt doped nickel (Ni0.5Co0.5Fe2O4) spinel ferrite nanocrystals with the aim of investigating the effect of Co doping on the structural and magnetic properties of NiFe2O4 nanocrystals. XRD analysis confirms the formation of a pure form of FCC nanocrystals of spinel ferrite type, where the average crystallite size has been found to be approximately 17 nm and 19 nm respectively for nickel ferrite (NF) and cobalt doped nickel ferrite (CNF) from XRD. Again, HRTEM study gives the average size for NF and CNF as 20 nm and 25 nm respectively. Further, SAED pattern indicates the polycrystallinity of both the sample, whereas EDX analysis confirms the presence of expected elements in the sample. From XRD data analysis different structural parameters such as lattice spacing, lattice constant, tetrahedral and octahedral ionic radii, oxygen position parameter, average cation radius per molecule, ionic packing coefficients (Pa, Pb), the degree of ionic packing (α), vacancy parameter (β), hopping lengths, and bond lengths etc. have been calculated for both nickel and cobalt doped nickel ferrite nanocrystals. Further, obtained cation distribution for NF and CNF nanocrystals from their XRD pattern analysis shows huge change in the distribution as a result of doping. In addition, FTIR spectral analysis also confirms the phase purity of both the samples. Magnetic characterization shows the improvement of different magnetic parameters due to cobalt doping on nickel, thereby making CNF nanocrystals suitable for different application purposes.

Stable and highly efficient natural sunlight driven photo-degradation of organic pollutants using hierarchical porous flower-like spinel nickel cobaltite nanoflakes

Hierarchical porous flower-like spinel nickel cobaltite (NiCo2O4) nanoflakes was synthesized by using simple and economical chemical method. The structure, morphology and optical properties of synthesizes nanoflakes were analyzed by using XRD, FE-SEM and UV–visible. The NiCo2O4 nanoflakes showed 96% degradation of TBO in 50 min and after 10 cycles of operation, the photocatalytic activity was enough for the 89% degradation of TBO under natural sun light. When compared with other photocatalysts materials, porous NiCo2O4nanoflakes showed excellent thermal and chemical stability and offer exceptional electron transfer rate during photocatalytic reactions for real environmental pollution cleanup applications. The efficient photocatalytic efficiency and stability of NiCo2O4 nanoflakes is attributed to its inimitable structure with large surface area along with maximum active sites. This augments the efficiency of harvesting sun light, and spread active species over surface to decrease e-/h+ pair recombination. On the whole, this work demonstrates that the synthesis of nanoflower NiCo2O4 can be used as potential candidate to remove organic pollutant and infections from water under natural sun light irradiations for industrial applications.

Spinel ferrite transformation for enhanced upgrading nickel grade in laterite ore of various types

Upgrading nickel grade in low-grade nickeliferous laterite ores before metallurgical extraction process is of utmost importance. However, most of nickel exists mainly in the form of isomorphism in serpentine or goethite, resulting in difficulty in upgrading of nickel by physical separation methods. In this paper, spinel ferrite transformation for enhanced upgrading nickel grade in laterite ore of various types was proposed. The mineral phase transformation and migration of valuable metals for various laterite ores during calcination process was investigated, as well the influences of mineral phases and chemical compositions on magnetic properties, separation efficiency, and nickel contents in separated laterite ore. The results show that spinel nickel ferrite mainly composed of nickel oxide and iron oxide could be completely formed after calcined at 800, 1000 and 900 °C for limonite, saprolite and transition laterite ore, respectively. With the increase of calcination temperature, the crystallinity and saturation magnetization Ms value of as-calcined samples become improved, leading to increased nickel recovery, while the nickel content in magnetic fraction is first increased and then slightly decreased. Under the optimum calcination conditions, the nickel recovery for limonite, saprolite and transition laterite ore could reach 68.5%, 68.9% and 67.3%, respectively, while the nickel contents in magnetic fraction are 3.01%, 3.23% and 3.15% with increasing by 1.82, 2.27 and 2.11 times, respectively. This paper could provide theoretical basis and technology support for enhanced upgrading of valuable metals from complex associated mineral resources.

Size-controlled synthesis of spinel nickel ferrite nanorods by thermal decomposition of a bimetallic Fe/Ni-MOF

In this work, size-controlled synthesis of nickel ferrite nanoparticles was achieved by the calcination of a bimetallic (Fe/Ni) metal-organic framework (MOF). The bimetallic MOF (Fe2Ni-MIL-88B) itself was prepared by a two-step route. The first step involved synthesis of the secondary building unit (SBU) by reacting stoichiometric amounts of Ni and Fe precursors with acetic acid. A ligand substitution reaction (terephthalate replaces acetate) in the SBU leads to the formation of the MOF, which was characterized by PXRD, FTIR, SEM and TEM. Afterwards, the MOF was calcined under air atmosphere to obtain nickel ferrite nanorods. PXRD analysis confirmed the spinel structure of the nickel ferrites while electron microscopic analysis (SEM, TEM) revealed their nanorod-like morphology. By increasing the calcination temperature from 600 to 1000 °C, particle size increased from 16 to 32 nm. Oxidation of benzyl alcohol was used as a model test reaction to probe the applicability of spinel nickel ferrite nanorods for catalysis. Interestingly, the largest nanorods exhibited the highest activity (86% conversion), thus demonstrating the potential of spinel ferrites in catalyzing oxidation reactions.

Facile fabrication of carbon-coated spinel nickel–cobalt–sulfide hollow spheres to achieve high-performance supercapacitors

This paper presents a simple method to prepare carbon-coated spinel nickel–cobalt–sulfide metal hollow spheres with excellent electrochemical properties.

Synergistic influence of mesoporous spinel nickel ferrite on the electrocatalytic activity of nano-structured palladium.

Structure and surface area are critical factors for catalysts in fuel cells. Hence, a spinel nickel ferrite mesoporous (SNFM) is prepared via the solution combustion technique, an efficient and one-step synthesis. Dynamic X-ray analysis has clarified the structural properties of SNFM. The grain size of SNFM is determined to be ∼11.6 nm. The specific surface area (87.69 m2. g−1) of SNFM is obtained via the Brunauer–Emmett–Teller method. The Barrett–Joyner–Halenda pore size distributions revealed that the size of the mesopores in as-synthesized SNFM mainly falls in the size range of 2–16 nm. Scanning electron microscopy studies showed the regularities involved during porous-structure formation. SNFM is employed as the support for nano-structured palladium (PdNS). Field emission scanning electron microscope studies of PdNS-SNFM showed the deposition of PdNS in cavities and on/in the pores of SNFM. The electrochemical surface area obtained for PdNS-SNFM is about 27 times larger than that of PdNS via cyclic voltammetry. The electrochemical studies are utilized to study the features and catalytic performance of PdNS-SNFM in the electro-oxidation of diverse small organic fuels, whereas the electrooxidation of diethylene glycol is reported for first-time.

Reagent-assisted hydrothermal synthesis of NiCo2O4nanomaterials as electrodes for high-performance asymmetric supercapacitors

Spinel nickel cobaltate nanoneedle arraysin situsynthesized by a CTAB assisted hydrothermal method show an energy density of 22.5 W h kg−1at 800 W kg−1.

Cu2+ doped nickel spinel ferrites (Cu x Ni1−x Fe2O4) nanoparticles loaded on CNTs for degradation of crystal violet dye and antibacterial activity studies

In the current work, Cu-doped Nickel ferrites (Cu x Ni1−x Fe2O4) integrated on carbon nanotubes (CNTs) were synthesized by wet-chemical method. The synthesized composite Cu x Ni1−x Fe2O4/CNTs along with pristine NiFe2O4 and Cu x Ni1−x Fe2O4 were characterized by X-rays diffraction (XRD), Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). XRD data confirmed the synthesis of NiFe2O4 and Cu x Ni1−x Fe2O4 with tetragonal lattice structure. The crystallite size varied from 26 to 35 nm with the substitution of Cu+2 ions in NiFe2O4 while Cu x Ni1−x Fe2O4/CNTs showed moderate crystallite size of 32 nm. SEM analysis showed spherical nanoparticles of Cu x Ni1−x Fe2O4 which transformed to aggregated blocks on combining with high surfaced CNTs. The conductivity of pure NiFe2O4 raised up to 0.028 and 0.22 S/m upon modification to Cu x Ni1−x Fe2O4 and Cu x Ni1−x Fe2O4/CNTs, respectively. Cu x Ni1−x Fe2O4/CNTs showed maximum degradation efficiency (92.9%) for CV, which was 1.4 and 1.8 folds higher than NiFe2O4 and Cu x Ni1−x Fe2O4, respectively.

Cd-Gd-doped nickel spinel ferrite nanoparticles and their nanocomposites with reduced graphene oxide for catalysis and antibacterial activity studies

During the past few decades, rapid industrialization of the world communities and over use of antibiotics in the medical field have badly influenced our natural ecosystem. Now, these ever-worsening issues have succeeded in drawing the attention of the researchers. In this connection, we have fabricated binary metal substituted nickel ferrite (Ni0.96Cd0.04Gd0.04 Fe1.96O4, NCGF) and its nanocomposite with r-GO via wet chemical method. The photocatalytic and antibacterial aptitude of the fabricated samples have been tested and compared by using organic pollutants (Methylene Blue and Rhodamine-B) and bacterial strains (Escherichia coli and Staphylococcus aureus), respectively as a representative. The nanocomposite showed better photocatalytic and antibacterial aptitude than that of pristine NCGF. More precisely, the NCGF/r-GO heterojunction based photocatalyst degraded 92.27% methylene blue (MB) dye and 53.18% Rhodamine-B (Rh–B) dye under visible light irradiation. In comparison, the NCGF photocatalyst degraded just 20.25% MB and 11.93% Rh–B dye under the same conditions. The higher activity of NCGF/r-GO photocatalyst is accredited to the suppression in the recombination process of the charge carriers caused by the addition of r-GO in the NCGF matrix. Moreover, the NCGF/r-GO photocatalyst retained 92% of its initial catalytic efficiency even after 5-recycles that indicate its higher stability and good reusability. Additionally, the NCGF/r-GO sample exhibited superior antibacterial aptitude than that of the pristine NCGF sample toward the E. coli and S. aureus bacteria. In fact, the primary constituent of the bacterial cell wall are organic compounds, lipopolysaccharide and peptidoglycan, that are also labile to degrade via photo-induced reactive oxygen species (HO•,O‾2•&H2O2 ). The leakage of K+ ions from the raptured cell wall, stop the crucial cell functions that result in the death of the whole bacterial cell. This work offers new insights for the fabrication of substituted ferrites nanomaterials for environmental protection and ecological safety.

Bottom Contact Metal Oxide Interface Modification Improving the Efficiency of Organic Light Emitting Diodes.

The performance of solution-processed organic light emitting diodes (OLEDs) is often limited by non-uniform contacts. In this work, we introduce Ni-containing solution-processed metal oxide (MO) interfacial layers inserted between indium tin oxide (ITO) and poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) to improve the bottom electrode contact for OLEDs using the poly(p-phenylene vinylene) (PPV) derivative Super-Yellow (SY) as an emission layer. For ITO/Ni-containing MO/PEDOT:PSS bottom electrode structures we show enhanced wetting properties that result in an improved OLED device efficiency. Best performance is achieved using a Cu-Li co-doped spinel nickel cobaltite [(Cu-Li):NiCo2O4], for which the current efficiency and luminous efficacy of SY OLEDs increased, respectively, by 12% and 11% from the values obtained for standard devices without a Ni-containing MO interface modification between ITO and PEDOT:PSS. The enhanced performance was attributed to the improved morphology of PEDOT:PSS, which consequently increased the hole injection capability of the optimized ITO/(Cu-Li):NiCo2O4/PEDOT:PSS electrode.

Properties of Al3+ substituted nickel ferrite (NiAlxFe2-xO4) nanoparticles synthesised using wet sol-gel auto-combustion

Currently, spinel ferrites are of great interest due to their large range of practical high frequency applications. Nickel spinel ferrites with formula NiAlxFe2-xO4 (where x = 0.0, 0.05, 0.10, 0.15, 0.20, 0.25) were prepared by a wet chemical sol-gel auto-combustion method. All the samples were annealed at 600 °C for 3 h and pellets were made to investigate the dielectric properties. The spinel structure of the nickel-based ferrites was confirmed by using X-rays diffraction analysis. The crystallite size was estimated using Scherrer’s formula and observed to be in the range from 11 to 17 nm. The addition of Al3+ varies the lattice constant from 8.26 to 8.35 A. The study of dielectric properties of interest (complex dielectric constant, dielectric tangent loss, impedance, A.C. conductivity, and electric modulus) as a function of the Al doping concentration was carried out in the frequency range from 1 MHz to 3 GHz using an impedance analyser. On the basis of these investigations, it was found that both the real and imaginary parts of the dielectric constant decreased with increasing applied frequency. Cole–Cole plots of electric modulus revealed evidence of contribution from grains and grain boundaries in the conduction mechanism. The observations revealed that with increasing aluminium doping, the dielectric properties of these ferrite materials are 6.

Bandgap and PL Spectra of Bismuth Ferrite-Nickel Ferrite Nanocomposites Synthesized by Wet Chemistry

Abstract: Perovskite bismuth ferrite and spinel nickel ferrite of the bismuth ferrite-nickel ferrite nanocomposite was synthesized using nitrate salts, glycerol and citric acid. Thermal analyses of mixed precursors were carried out to determine crystallization followed by annealing and phase analysis by XRD to determine the crystal structure of the sample. Optical properties of the synthesized samples were determined by UV-VIS spectra and PL spectra analyses. The bandgap was measured by a Tauc plot, while luminescence properties were measured using PL spectra analyses.

Microwave Catalytic Degradation of Antibiotic Molecules by 2D Sheets of Spinel Nickel Ferrite

Pharmaceutical wastes such as antibiotics in the industrially polluted water are hazardous for the aquatic ecosystem and the environment and, hence, need to be adequately treated. Prompt and effici...

Effect of Ni2+ and Fe3+ Ion Concentrations on Structural, Optical, Magnetic, and Impedance Response of NiFe2O4 Nanoparticles Prepared by Sol-Gel Process

In this study, NiFe2O4 (1:1, 1:2, 1:3, 2:1, and 3:1) nanoparticles were synthesized via sol-gel method and thermally treated at 900 °C. The reflection planes with single and two phases by homogeneous and nonhomogeneous distributions of Ni2+ and Fe3+ ions in cubic spinel nickel ferrite samples confirmed by using XRD patterns through the Rietveld refinement method and FTIR analysis. The changes in structural parameters correlated with the morphology and elements obtained from FESEM and EDS analysis. UV-vis diffuse reflectance spectra images indicate that the band gap ranges from 1.87 to 1.57 eV by varying the ratios of precursors. The homogeneity of Ni2+ and Fe3+ ions between the octahedral and tetrahedral sites plays a desired role in the magnetic and impedance responses. Maximum saturation magnetization of 66.26 emu/g with pure ferromagnetic behavior and high impedance response of 1.15 × 105 Ω were obtained, and then the value decreased due to the nonhomogeneous distribution.

High-performance photocatalysis afforded by g-C3N4/NiCo2O4-decorated carbon cloth

We report a novel photocatalyst by constructing graphitic carbon nitride (g-C3N4)/spinel nickel cobaltite (NiCo2O4) heterojunctions on carbon cloth (CC). The growth of tubular g-C3N4 with a wall thickness of 20 nm on CC was performed via a thermal condensation method with ZnO nanorods as the sacrifice templates. The growth of NiCo2O4 nanosheets with a thickness of 10 nm on tubular g-C3N4 was realized by electrodeposition and calcination. Under visible light, the prepared g-C3N4/NiCo2O4/CC and g-C3N4/CC photocatalysts could remove 97% and 36% ciprofloxacin in 60 min, respectively. After 5 cycles, the photocatalytic activity did not decrease significantly. The photocatalysts with high catalytic activity were grown on CC and show promising potential applications for the degradation of organic pollutant in water. This strategy could potentially be extended to adapt to major areas for other applications.

Rare earth Ce- and Nd-doped spinel nickel ferrites as effective heterogeneous catalysts in the (ep)oxidation of alkenes

Cerium (Ce)- and neodymium (Nd)-doped spinel nickel ferrites catalysts system were synthesized using a cost-effective sol–gel route. The as-prepared nickel ferrites and its doped Ce and Nd nanomaterials were characterized in terms of Fourier transform infrared spectrophotometry, X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, selected area diffraction pattern, zeta potential and magnetism techniques. Their catalytic potential was examined in the (ep)oxidation of 1,2-cyclooctene by using hydrogen peroxide (H2O2) or tert-butylhydroperoxide (t-BuOOH). Optimization of various parameters, including solvent, oxidant and catalyst type revealed that chloroform (CHCl3) or 1,2-dichloroethane as a solvent and t-BuOOH as an oxidant were found to be the best choice for this catalytic system. The catalytic efficiency was found as Nd–NiFe2O4 > Ce–NiFe2O4 > NiFe2O4. Further, the applied nanocatalysts could be easily renovated and exhibited high catalytic reactivity for 5 times of recycling experiments with long-time durability. A reasonable discussion of the mechanism reaction reinforced the action of these spinel catalysts.

Magnetic characterization of Nickel-Zinc spinel ferrites along with their microwave characterization in Ku band

The present manuscript deals with the magnetic and microwave absorption characteristics of zinc substituted nickel spinel ferrites with chemical formula Ni1−xZnxFe2O4 where x varies from 0 to 1 (Δx = 0.2). The synthesis method adopted is Sol-gel citrate precursor method. Vibrating Sample Magnetometer (VSM) has been employed to determine the magnetic properties. The electromagnetic and absorption properties have been determined using Vector Network Analyzer (VNA) in Ku band (12.4–18 GHz). RL as low as −31.17 dB (~99.92% absorption) has been obtained for composition x = 0.2 at a pellet thickness of 3 mm. Such a low value of RL make these Nickel-Zinc ferrites excellent absorbers, which can work at gigahertz frequencies in different applications such as radar stealth technology.

Study on the novel capacitive moisture sensing behaviour of nickel chromite nanoparticle based thick film

Abstract In this work, the novel and appreciable humidity sensing properties of microporous, spinel nickel chromite thick films are reported for the first time. NiCr2O4 microporous, thick film prepared by tape casting of sol-gel derived nanopowder followed by sintering was sandwiched between two parallel silver electrodes to develop capacitive humidity sensor. Condensation in the surface pores and physisorption on the sensor surface are found to be responsible for the humidity sensing properties. The sensor shows excellent humidity sensing properties in the range of 5 to 95% RH (relative humidity) with a resolution of ∼3 pF/%RH in the lower humidity range (5% - 30% RH) at 1kHz external electric field. The sensor also exhibited excellent repeatability (at least 50 cycles of 5%-95%RH), good stability of at least 6 months, and low hysteresis loss. The thick film sensors were characterized by XRD, FT-IR, FESEM, TEM, EDX, and contact angle measurement.

Facile synthesis of solar light active spinel nickel manganite (NiMn2O4) by co-precipitation route for photocatalytic application

The spinel nickel manganite (NiMn2O4) nanoparticles (NPs) were successfully synthesized through simple co-precipitation method, and their structural, optical, morphological and photocatalytic behavior is examined in this investigation. The powder X-ray diffraction pattern confirms the face-centered cubic spinel structure of the as-prepared sample, and the average crystallite size is found to be 46.27 nm. The absorption spectrum of the material was obtained via diffuse reflectance spectroscopy (UV-DRS), and the bandgap value is calculated using Tauc’s relation as 2.41 eV. Morphological analysis was investigated by using a scanning electron microscope (SEM). From the SEM analysis, the hexagonal cake-like structure was observed from the prepared material and size was achieved around to be 50–100 nm. Furthermore, the photocatalytic behavior of NiMn2O4 (NPs) against organic dyes under direct sunlight was analyzed by using methylene blue, malachite green and Congo red and the efficiency is observed as 92%, 94% and 62%, within 120 min, 60 min and 120 min, respectively.

Hot corrosion behavior of nanostructured and conventional HVOF Cr3C2NiCrBSi coatings on superalloy

In the present work, optimized Cr3C2NiCrBSi nanostructured and conventional powder coatings are sprayed on to Inconel 718 material by high-velocity oxygen fuel coating process for enhancing the high temperature corrosion resistance. The cyclic hot-corrosion study is carried out on uncoated, conventional coated and nanostructured coated superalloy in the salt environment of Na2SO4 and 60% V2O5 at 900 °C. The weight change measurements are carried out after each cycle to investigate the hot corrosion kinetics of uncoated and coated superalloy using thermo gravimetric technique. The corrosion products of coated specimens are analysed using Scanning electron microscopy and Elemental mapping. Cr3C2NiCrBSi nanostructured coating provides dense coating compared to conventional coating. Compared to uncoated sample, Cr3C2NiCrBSi coating is found to be highly effective in corrosive resistance. The hot corrosion resistance provided by Cr3C2NiCrBSi coatings may be associated with the development of oxides of chromium, nickel, silicon and spinels of chromium and nickel.