Fe Nitrates Research Articles

Electrochemical studies: Biological evaluation of the homometallic‐binuclear complexes of malonate‐derived tetradentate O2N2 ligand

Novel metal complexes were synthesized by mixing N1,N3‐bis(4‐phenylthiazol‐2‐yl)malonamide with Cr (III), Fe (III), Cu (II), and Zn (II) nitrates in a 1:2 (L: metal) ratio. Through the use of several analytical and spectral methods, the structures of all compounds were determined. It was determined that the novel ligand functions through O2N2 sites as a neutral tetradentate. The thermal stability and the thermodynamic parameters were evaluated using thermal gravimetric analysis and the Coats‐Redfern equations. Powder X‐ray diffraction investigation revealed the type of unit cell and the degree of crystallinity. The complexes were further tested for their antibacterial efficacy, with molecular simulation using several proteins demonstrating the strongest action against a range of pathogens. Optimization for all compounds were made through the basis set DFT/B3LYP/LANL2DZ to find the theoretical stability, FMO orbitals, energy gaps, molecular electrostatic potentials (MEPs), and evaluate physical parameter. Here, the electrochemical properties of the metal complexes were investigated using cyclic voltammetry and electrochemical impedance spectroscopy methods. Additionally, [Cr2(L)(NO3)4(H2O)4](NO3)2 complex has been authorized that has high electrocatalytic characteristics, making it attractive for use in supercapacitor applications.

Технология изготовления и свойства высокотемпературных пьезокерамических материалов на основе фаз системы (1 – у)(Bi0,8Ba0,2)Fe0,8Ti0,2O3 – у(Ba0,85Ca0,15)Ti0,90Zr0,10O3

In technology, using as precursors Fe(III) and Bi(III) nitrates, peroxo-nitrate complexes Ti(IV) and Zr(IV), as well as barium and calcium hydroxides, ultrafine powders of the (1 – у)Bi0.8Ba0.2Fe0.8Ti0.2O3 – уBa0.85Ca0.15Ti0.9Zr0.1O3 (у = 0,05 – 0,30). To reduce the electrical conductivity of ceramic samples made from these powders, the basic phases were alloyed with manganese compounds. To increase the d33 values of the piezoelectric elements, as well as to increase their operating temperature, a special sintering regime involving air hardening of the ceramic samples was used. The best samples of piezoceramics produced by the proposed technology have a Curie temperature above 550 °C and longitudinal piezoelectric modulus (standard conditions) values d33 ≥ 125 pC/N and their operating temperature reaches 340 – 350 °C.

Synthesis of KBiFe2O5 by electrospinning: Structural, optical, and magnetic properties

Ferroelectric oxides are currently being studied as absorbing materials in photovoltaic devices due to their spontaneous polarization that facilitates charge separation. KBiFe2O5 (KBFO) is a ferroelectric oxide with a perovskite like structure that has a low band gap; however, it has a relatively low electrical conductivity, which makes it difficult to transport and collect carriers. One way of overcoming that deficiency would be by decreasing the dimensions of the active layer. Thus, in this work, for the first time, nanofibers of KBFO were produced by electrospinning. Aqueous solutions of the ceramic precursors in the form of Fe, K and Bi nitrates were electrospun using poly (vinylpyrrolidone) (PVP) as the carrier. The as-spun fibers were calcinated at different temperatures and times. The pure KBFO phase was obtained after calcination at 750 °C, during 1.5 h at 15 °C/min; the nanofibers had diameters between 300 nm and 800 nm as analyzed by scanning electron microscopy (SEM). The interplanar distances of the (100) and (111‾) planes were 0.78 and 0.37 nm, respectively, as calculated by a VESTA software, x-ray diffraction (XRD) and transmission electron microscopy (TEM). Using a Magnetization-Field (MxH) curve, KBFO was found to be highly paramagnetic with low magnetization. The band gap was measured by spectrophotometry via a Tauc plot, resulting in a value of 1.72 eV. Therefore, KBFO in the form of nanofibers seems to have a high potential as an absorbing material in photovoltaic cells.

Effect of annealing temperature and cadmium doping on structure and magnetic properties of neodymium orthoferrite nanoparticles synthesized by a simple co-precipitation method

A series of Nd1-xCdxFeO3 (x = 0.1, 0.2 and 0.3) nanoparticles were successfully synthesized from Nd(III), Cd(II) and Fe(III) nitrates by a simple co-precipitation method in boiling water with a 5% sodium hydroxide aqueous solution (without any surfactants) and annealed at 700, 850 and 950?C for 1 h. SEM and TEM analyses showed particle sizes in the range of 50-70 nm. According to XRD the average crystallite size increased with the annealing temperature, but decreased when the cadmium concentration increased. As the annealing temperature was raised from 700 to 950?C, the magnetic properties, such as coercivity (Hc), remanent magnetization (Mr) and saturation magnetization (Ms), of the Nd0.8Cd0.2FeO3 sample also increased. In general, the Hc, Mr and Ms values increased with the degree of cadmium doping. The synthesized Nd1-xCdxFeO3 nanopowders havemuch larger coercivity values than some other rare-earth perovskites, such as Nd1-xSrxFeO3, NdFe1-xCoxO3, LaFe1-xTixO3, YFe1-xNixO3, Y1-xCdxFeO3, La1-xCdxFeO3 or Bi1-xCdxFeO3. The high Hc value (1916.52-4833.41Oe) of the synthesized Nd1-xCdxFeO3 nanopowders enables their use for permanent magnets or magnetic recording on hard disks and tapes.

Microstructure, magnetic, and dielectric interplay in NiCuZn ferrite with rare earth doping for magneto-dielectric applications

The homogeneous conglomerate of ferrite oxide samples with increasing concentration of Neodymium and Lanthanum in the steps 0.02 with the chemical formula Ni0.6Cu0.2Zn0.2Fe2-x(Nd0.5La0.5)xO4 (0 ≤ x ≤ 0.10) were achieved by novel citric acid-metal nitrate sol–gel auto-ignition method. The nano-regime crystallites products were achieved by using Ni, Cu, Zn, La, Nd and Fe nitrates and keeping the metal nitrate to citrate ratio 1:1. The products of ensured recipe in the form of chemical formula resulted in precursor powders were calcined for removal of desiccated impurities. The ready blends were subjected to an exhaustive examination with distinctive characterizations. The completion of the reaction and phase formation temperature was confirmed by thermal analysis and structural confirmations were received by X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) spectra. The analytics regarding the local symmetry in crystalline solids and understandings about the ordering phenomenon were discussed with the support of FTIR spectra. The diffractograms contributed to the corroboration that the powders obtained were bearing single phase and spinel structure. Evaluation of TEM and DLS confirms fine particle nature of the particles. SEM analysis and EDAX indicated that the samples were having dense, homogeneous and expected stoichiometric cation ratios. The neodymium and lanthanum content influenced the measured saturation magnetization negatively and coercivity positively. The heightened values in electrical conductivity, high ε′ and low dielectric losses in combination with high saturation magnetization, low coercivity, observed in the present samples make them prospect candidate for microwave and electromagnetic shielding applications.

MCC: Specific of preparation, correlation of the phase composition and electrodynamic properties

Metal-carbon composites (MCC) were produced by the dissolving of the Fe, Co and Ce nitrates in phenol–formaldehyde resin with further pyrolysis (under heating up to 800 °C). Concentrations of the metal compositions in final MCC were 2, 7 and 15 wt%. Phase composition of the final MCC samples was determined using XRD and Mössbauer spectroscopy. It was established phase separation in metallic compounds under pyrolysis process due to chemical interaction with phenol–formaldehyde decomposition products. The main phases for composites were: Fe3O4 (for MCC-Fe); Co (for MCC-Co) and CeO2 (for MCC-Ce). Average crystal size for metal-based fillers was 28, 24–35 and 3.5 nm for Fe-; Co and Ce-based composites respectively. The electrodynamic properties of the MCCs in the Extremely High Frequency range (30–50 GHz) were studied as function of the filler concentration. The frequency dependences of the permittivity and permeability (real and imaginary parts) of the investigated composites were measured. The nature of the MCC electrodynamic properties was discussed in detail in terms of polarization losses.

Polymer-mediated synthesis of Fe-Co nanocrystalline alloys: Formulation and properties

FeCo nanoalloy particles encapsulated in N-doped carbonized shell FeCo/C-N were synthesized by thermolysis at 400 °C of polyacrylamide complex FeCoPAAm following frontal polymerization of co-crystallizate of Fe and Co nitrates and acrylamide (AAm). During the annealing of FeCoPAAm in argon atmosphere, Co (II) and Fe(III) cations are reduced to form CoFe nanoalloy particles, while simultaneously PAAm forms nitrogen-doped carbon shell layer. Such unique architectures offer not only high chemical and thermal stability, but also a high magnetic properties. The average crystalline size of FeCo nanoparticles is 50 nm. The measurements of magnetic hysteresis loops showed that the coercive force and residual magnetization at room temperature are 119,5 Oe and 10 emu/g, respectively.

Thermal behavior of Ni, Co and Fe succinates embedded in silica matrix

This paper presents the thermal behavior of Co, Ni and Fe succinates obtained by sol-gel synthesis using Co(II), Ni(II) and Fe(III) nitrates, 1,4-butanediol and tetraethyl orthosilicate as reactants. The thermal analysis revealed the formation of succinates at 413–453 K and their decomposition to ferrites at 503–623 K. The rate constants for the decomposition of succinates to ferrites, calculated using the isotherms at 473, 523, 573 and 623 K, were used to determine the activation energy of each ferrite (NiFe2O4, Ni0.3Co0.7Fe2O4, Ni0.7Co0.3Fe2O4 and CoFe2O4) embedded in the silica matrix. By increasing the Ni content in the mixed Ni–Co ferrites, the activation energy decreases from 13.530 to 1.944 kJ mol−1. The formation and decomposition of succinate precursors and the formation of silica matrix were confirmed by FT-IR spectroscopy, while the formation of CoFe2O4 and NiFe2O4 single-phases embedded in the silica matrix was confirmed by X-ray diffraction analysis. The nanocrystallites size decreases from 31.7 (CoFe2O4) to 18.5 nm (NiFe2O4). The optical band gap of mixed Co–Ni ferrites was significantly higher than that corresponding to CoFe2O4. The photocatalytic activity of the samples was evaluated against Rhodamine B under visible light. All the samples have photocatalytic activities, the best performance being obtained in the case of Ni0.7Co0.3Fe2O4.

Magnetic properties of biocompatible [formula omitted] nanoparticles using a facile synthesis

Cobalt ferrite (CoFe2O4) nanoparticles were synthesised by a simple and cost-effective method using Co and Fe nitrates and freshly extracted egg white in an aqueous medium. X-ray diffraction patterns and Selected Area Electron Diffraction (SAED) pattern results indicate that the CoFe2O4 nanoparticles have spinel structure with Fd3¯m space group. The average particle size of CoFe2O4 nanoparticles is found to from 45 nm. Temperature and field dependence of magnetisation reveals that the CoFe2O4 nanoparticles form ferrimagnetic in nature. A null cytotoxicity is observed in the CoFe2O4 nanoparticle which indicates that the material has an excellent biocompatibility. In order to check the importance of CoFe2O4 nanoparticles using the egg-white synthesis, the structural, magnetic and cytotoxicity of CoFe2O4 nanoparticles prepared via egg white method have been compared with that of sol–gel method. The egg-white method adopted in the present study appears to be a promising route of CoFe2O4 nanoparticles for biomedical applications.

Size and shape-controlled synthesis and characterization of CoFe2O4 nanoparticles embedded in a PVA-SiO2 hybrid matrix

This study presents the controlled synthesis and characterization of CoFe2O4 nanoparticles embedded in a PVA-SiO2 hybrid matrix. The sol-gel method consists in the embedding of reactants (Co and Fe nitrates and 1,4-butanediol) in a matrix containing high molecular weight poly(vinylalcohol) and tetraethylorthosilicate, and in the formation and decomposition of succinate precursors followed by a controlled thermal decomposition (400–1000°C). The thermal analysis and Fourier transformed infrared spectroscopy confirmed the formation of succinate precursors and hybrid matrix, while X-ray diffraction indicated the formation of single phase CoFe2O4. Transmission electron microscopy revealed the shape and size of CoFe2O4 nanoparticles, while scanning electron microscopy indicated the morphology of CoFe2O4/SiO2-PVA particles. The particle size of ferrite is critically dependent on the annealing temperature and CoFe2O4:PVA-SiO2 molar ratio.

Sol-gel synthesis of CoFe2O4:SiO2 nanocomposites – insights into the thermal decomposition process of precursors

Succinate precursors dispersed in the silica matrix were obtained by sol-gel synthesis using Co and Fe nitrates, 1,4-butanediol and tetraethyl orthosilicate. The thermal decomposition of Co and Fe succinates into cobalt ferrite (CoFe2O4) at different CoFe2O4:SiO2 molar percentages was studied by thermal analysis, Fourier transformed infrared spectrometry (FT-IR) and X-ray diffraction. The morphology of nanoparticles was identified by transmission and scanning electron microscopy. The formation of succinates in the pores of the silica matrix and their decomposition to CoFe2O4 spinel was confirmed by the FT-IR spectra. The nanocrystallites size (7–33nm) increases with the decrease of SiO2 content, suggesting that the growth process of nanoparticles is reduced in the presence of silica matrix.

Determination of lithium in lithium-ionic conductors by laser-enhanced ionization spectrometry with laser ablation

Laser-enhanced ionisation (LEI) with laser ablation (LA) into a methane–air flame was used for lithium determination in ferrites. Since there is a lack of certified reference materials matrix-matched to ferrites powders, a set of spinel samples were synthesised by means of aerosol spray pyrolysis (ASP) or by annealing the mixture of Li and Fe(III) nitrates. Characterisation by X-ray diffraction showed that the annealed ceramics contained two phases, such as either α-LiFe5O8 and Fe2O3 or α-LiFeO2 and Fe2O3, while ASP ferrites consisted mainly of α-LiFe5O8. Total lithium content in samples was certified by conventional flame photometry after dissolution. We explained the strong matrix effects on the LA-LEI signal by the discrepancy of surface microstructure (and hardness) due to the difference in the conditions of sample preparation. The optoacoustic signal and emission line of Fe I at 382 nm were recorded simultaneously with the LA-LEI signal in order to compensate for matrix effects. We suggest that the microstructure (ceramics or pellets from spherical microparticles) influences both mass removal (proportional to OA signal) and plasma temperature (proportional to AE signal). Correlation plots between OA and AE signals deviated strongly from sample to sample, which was the basis for the application of a multivariate correction procedure to reduce strong matrix effects. 3D correlation plots (LEI vs. OA + AE) for each sample were built to obtain a new analytical signal, which represented the slope of the correlation line to the plane of the OA + AE signals. This normalised signal was free from matrix effects within a concentration range of 0.6–7.5 Li%. The proposed approach allows the use of ferrites synthesised by the various techniques as reference materials in order to build a unified calibration curve.

Fabrication and Characterization of Multiwalled Carbon Nanotubes-Alumina Hybrid Compound: Comparison of Various Supported Catalyst

Hybrid compounds of multiwalled carbon nanotubes-alumina (MWCNT-Al2O3) were grown by chemical vapour deposition (CVD) method of methane. The catalyst effect and growth of the synthesis of the multiwalled carbon nanotubes-alumina (MWCNT-Al2O3) hybrid compound in three different supported catalysts (Ni, Co and Fe nitrates) were being compared. X-Ray diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM) were employed for the characterization of the hybrid compound. The results revealed that the Ni nitrates catalysts showed a better growth rate performance than Co Nitrates and Fe Nitrates. With respect to the diameter of the MWCNT-Al2O3,the Fe nitrate showed lengthens in diameter compared to Co Nitrates and Ni Nitrates catalyst. This indicated that the growths of these carbon structures can be controlled and manipulated by the supported catalyst.

Effect of the Support on the Formation of FeCo Alloy Nanoparticles in an SBA-16 Mesoporous Silica Matrix: An X-ray Absorption Spectroscopy Study

A series of nanocomposites consisting of FeCo alloy nanoparticles supported on a three-dimensional cubic mesoporous silica matrix (SBA-16) were prepared by wet impregnation of the matrix with a solution of Fe and Co nitrates. FeCo alloy nanoparticles were obtained by heat treatment at 800 °C in reducing atmosphere of the impregnated SBA-16 previously calcined at 500 °C. Three different SBA-16 types were used as a support of the nanophase. The influence of the matrix on the absorption of Fe and Co ions was investigated using X-ray diffraction and X-ray absorption spectroscopy. In particular, extended X-ray absorption fine structure (EXAFS) and X-ray absorption near-edge structure (XANES) techniques at the Fe and Co K-edges were used in order to identify the intermediate products before reduction and to study the formation of the bcc FeCo alloy, which cannot be assessed unambiguously using X-ray diffraction. An important influence of the matrix has been observed in the phases formed before reduction, in the size of nanoparticles, and in the oxidation of the FeCo alloy nanoparticles.

Synthesis, Characterization and Biological Evaluation of Fe (III), Co (II), Ni(II), Cu(II), and Zn(II) Complexes with Tetradentate Schiff Base Ligand Derived from Protocatechualdehyde with 2-Aminophenol

Schiff base ligand (H(3)L) was prepared from the condensation reaction of protochatechualdehyde (3,4-dihydroxybenzaldhyde)with 2-amino phenol. From the direct reaction of the ligand (H(3)L) with Co(II), Ni(II) and Cu(II) chlorides, and Fe(III)and Zn(II)nitrates in 2 M/1 L molar ratio, the five new neutral complexes were prepared. The characterization of the newly formed compounds was done by (1)H NMR, UV-Vis, and IR spectroscopy and elemental analysis. The in vitro antibacterial activity of the metal complexes was studied and compared with that of free ligand.

ChemInform Abstract: Reduction‐Tolerant Oxygen‐Permeable Perovskite‐Type Oxide Sr0.7Ba0.3Fe0.9Mo0.1 O3‐δ.

AbstractThe title compound, a new mixed ionic‐electronic conducting material, is synthesized by a combined EDTA—citrate complexing sol—gel process from Sr, Ba, and Fe nitrates, and MoO3 (calcination in air at 950 °C for 5—10 h, sintering at 1200 °C for 5—10 h).

Synthesis of Zn0.5Mn0.5Fe2O4 by low-temperature spray pyrolysis

The effect of synthesis temperature on the structural perfection of the Zn0.5Mn0.5Fe2O4 ferrite synthesized via spray pyrolysis of a solution of Zn(II), Mn(II), and Fe(III) nitrates has been studied using X-ray diffraction, scanning electron microscopy, and IR spectroscopy. The material obtained at 650°C is shown to have a nanocrystalline structure. IR spectroscopy results indicate that the synthesized Zn0.5Mn0.5Fe2O4 spinel ferrite is highly homogeneous in composition and structure.

Structural, morphological and magnetic properties of NiFe 2O 4 nano-particles

NiFe 2O 4 nano-particles were synthesized by a simple and cost-effective method using Ni and Fe nitrates and glycine. Significant effect of the ratio between glycine and nitrates on the physical parameters like crystalline phase, crystallite size, and particle size, lattice constant and magnetic properties of the nano-particles has been investigated. The X-ray diffraction, IR and selected-area electron diffraction results indicated that the synthesized nickel ferrite particles have the nanometer size and inverse spinel structure. Room temperature magnetization results showed a ferromagnetic behavior of the NiFe 2O 4 nano-particles, with saturation specific magnetization values in the range of 2.387–57 emu/g at 15 kOe. The corecivity of the NiFe 2O 4 nano-powders changed from 65.58 to 148.8 Oe according to the change in the ratio between glycine and nitrates.

Recent progress in Japan on hot gas cleanup of hydrogen chloride, hydrogen sulfide and ammonia in coal-derived fuel gas

The present review paper highlights on the recent progress in Japan on the hot gas cleanup of HCl, H 2S and NH 3 in raw fuel gas for coal-based, combined cycle power generation technologies. It has been shown that NaAlO 2, prepared by mixing Na 2CO 3 solution with Al 2O 3 sol, can reduce HCl in an air-blown gasification gas from the initial 200 ppm to < 1 ppm at 400 °C, and it is tolerable for 200 ppm H 2S. With regard to the removal of H 2S, studies on the stability and durability of ZnFe 2O 4 sorbent in a simulated fuel gas have indicated the presence of an optimal operation temperature from the viewpoint of the suppression of both vaporization of metallic Zn and carbon formation from CO. High-performance TiO 2-supported ZnFe 2O 4, which can decrease 1000 ppm H 2S to < 1 ppm at 450 °C and 1 MPa, has been developed by the homogeneous precipitation method using a mixture of SiO 2 sol and an aqueous solution of Zn and Fe nitrates, followed by mixing with TiO 2. Although this sorbent is regenerable and durable, the sorption ability should be improved in a syngas-rich fuel gas from an O 2-blown gasifier. A novel method to prepare carbon-supported ZnFe 2O 4 and CaFe 2O 4 by impregnating the corresponding nitrate solution with brown coal has been proposed, and the large desulfurization capacity of almost 100% has been achieved in the removal of 4000 ppm H 2S around 450 °C. The present authors have demonstrated that an Australian limonite rich in α-FeOOH is practically feasible as the catalyst material for the decomposition of 2000 ppm NH 3 in a syngas-rich gas of 25 vol.% H 2/50 vol.% CO at 750 °C, because small amounts of H 2O and CO 2 added to the gas can work efficiently for inhibiting carbon deposition from the CO.

Direct synthesis of graphitic carbon nanostructures from saccharides and their use as electrocatalytic supports

An easy method is described for fabricating graphitic carbon nanostructures (GCNs) from a variety of saccharides; i.e., a monosaccharide (glucose), a disaccharide (sucrose) and a polysaccharide (starch). The synthesis scheme consists of: (a) impregnation of saccharide with Ni or Fe nitrates, (b) heat treatment under inert atmosphere (N 2) up to 900 °C or 1000 °C and (c) oxidation in liquid phase to selectively recover the graphitic carbon. This procedure leads to GCNs with a variety of morphologies: nanopipes nanocoils and nanocapsules. Such GCNs have a high crystallinity, as shown by TEM/SAED, XRD and Raman analysis. The GCNs were used as supports for platinum nanoparticles, which were well dispersed (Mean Pt size ∼ 2–3 nm). Electrocatalysts thus prepared have electrocatalytic surface areas in the 70–95 m 2 g −1 Pt range and exhibit high catalytic activities towards methanol electrooxidation.