Synthesis of Gd2SiO5 nano-powders by cocurrent chemical co-precipitation method

In this research, the synthesis of CuO nano powders via chemical method and using organic materials has been investigated. The raw materials were Ammonium Oxalate and Copper nitrate which have been mixed together having the ratios of 1/1, 1/2, 1/3 and 1/4 which resulted into Copper oxalate after reaction. SEM and XRD examinations confirm the 1/2 one as the optimum ratio for which the produced oxalate was heat treated for three temperatures of 600, 700 and 800 to synthesize nano powders of Copper oxide.

Although acetaminophen is a widely used analgesics and antipyretic drug, its overdose leads to many complications. Therefore, determining the correct dose of produced or imported drugs in clinical laboratories or a standard laboratory is essential. Different analytical methods, for example chromatography, spectroscopy and electrochemistry, can be utilized to determine the correct dose of acetaminophen. However, it is believed that electrochemical methods are more efficient due to their fast response and low cost. In this study, we synthesized NiO/CNTs nanocomposite by a direct chemical precipitation method for acetaminophen analysis using a voltammetric sensor. A chemical precipitation method was used for synthesis of NiO/CNTs nanocomposite in the nanoscale. The synthesis of nanopowder was investigated using scanning electron microscopy (SEM) and X-ray powder diffraction. The obtained result confirms the synthesis of nanocomposite with chemical precipitation method with ~35.5 nm diameter for NiO nanoparticle, as established by the Scherrer equation. The results show that the synthesized nanocomposite can modify a carbon paste electrode as a sensor for the analysis of acetaminophen.

Zinc ferrite samples were prepared by two different routes which are chemical co-precipitation and standard solid state double sintering method. Structural properties of ZnFe2O4 were determined, and initial particle size was found as 5 nm in the samples prepared by chemical co-precipitation technique. The XRD patterns showed the single phase of ZnFe2O4 spinel structure and confirmed by the lattice parameter and the unmixed hkl values for both the synthesis techniques. M-H curves at room temperature showed superparamagnetic nature of the samples sintered from 200°C to 600°C, synthesized by chemical co-precipitation technique. The Mössbauer analysis at room temperature showed a doublet which is the signature of superparamagnetic nature, and it is in agreement with the acquired M-H curves. The magnetization of ZnFe2O4 synthesized by chemical co-precipitation method was found higher than the magnetization of ZnFe2O4 synthesized by the solid-state double sintering method in the sintering temperature from 1100°C to 1300°C.

Hydrothermal synthesis and thermophysical properties of (Sm1-Gd )2Zr2O7 (0≤x≤1) thermal barrier coating materials

Nanocrystalline ferrites; CoFe₂O₄ (CFO) and CoFe₁.₉Zr₀.₁O₄ (CFZO) have been synthesized through chemical coprecipitation method. The role played by the zirconium ions in improving the magnetic and structural properties is analyzed. X-ray diffraction revealed a single-phase cubic spinel structure for both materials, where the crystallite size increases and the lattice parameter decreases with substitution of Zr. The average sizes of the nanoparticles are estimated to be 16-19 nm. These sizes are small enough to achieve the suitable signal to noise ratio in the high density recording media. The increase in the saturation magnetization with the substitution of Zr suggests the preferential occupation of Zr⁴⁺ ions in the tetrahedral sites. A decrease in the coercivity values indicates the reduction of magneto-crystalline anisotropy. In the present study the investigated spinel ferrites can be used also in recoding media due to the large value of coercivity 1000 Oe which is comparable to those of hard magnetic materials.

Synthesis and properties of barium ferrite nano-powders by chemical co-precipitation method

The kinetic characteristics of the process of synthesis of Ni nanopowder (NP) by the chemical metallurgy method are studied. Nickel NP is obtained by reduction of NiO nanopowder with hydrogen in a tubular furnace at temperatures in the range from 240 to 280°C. Nickel oxide nanopowder is prepared by thermal decomposition of nickel hydroxide Ni(OH)2 at 300°C, which has been synthesized in advance by chemical precipitation from aqueous solutions of nickel nitrate 10 wt % and alkali NaOH 10 wt % with pH 9 at room temperature. It is found that NiO NP is more readily reduced at temperatures above 250°C. The rate constant of the reduction process at 280°C is about 2.5 times higher than in the case of reduction at 240°C. The duration of the reduction process at 280°C is shorter by a factor of more than two in comparison with the case of reduction at 240°C. Based on the results of calculation of the activation energy of the reduction process from isothermal data, an assumption is made about the kinetically controlled rate-limiting regime of the reduction of NiO NP. It is revealed that Ni nanoparticles obtained by hydrogen reduction of nickel oxide have an average size in the range of 60–120 nm, and each of them is connected to several adjacent particles by necks.

Synthesis and characterization of palladium nanoparticles by chemical and green methods: A comparative study on hepatic toxicity using zebrafish as an animal model

An insight into formation mechanism of rapid chemical Co-precipitation for synthesizing yttrium iron garnet nano powders

Magnesium aluminate spinel nano-powders were synthesised by the wet chemical co-precipitation method. First, the gel-like precursors were obtained by dropping ammonia into the mixed solution of magnesium chloride hexahydrate and aluminium chloride hexahydrate with different Mg2+/Al3+ molar ratios and concentrations. After drying, the precursors were calcined at 700°C, 800°C, 900°C, 1000°C and 1100°C for 1.5 hours, respectively. Finally, the obtained samples were characterised by X-ray diffraction, thermal gravimetric and differential thermal analysis and scanning electron microscopy. It was revealed that the pure phase of MgAl2O4 started to form when the calcination temperature exceeded 700°C, and MgAl2O4 spinel with the smallest average crystallite size could be obtained when the calcination temperature reached 900°C.

Synthesis and effect on the surface morphology & magnetic properties of ferrimagnetic nanoparticles by different wet chemical synthesis methods

Conventional wet chemical methods for the synthesis of superparamagnetic magnetite nanoparticles (MNPs) are energy-intensive and environmentally unsustainable. Green synthesis using bacteria is a less-explored approach to MNP production. Large-scale biosynthesis of MNPs has heretofore been conducted using extremophilic bacteria that exhibit low growth rates and/or require strict temperature control. However, a decrease in material and energy costs would make such bioprocesses more sustainable. In this study, Shewanella putrefaciens CN-32, an iron-reducing bacterium, was employed to reduce amorphous iron oxyhydroxide and synthesize MNPs in a non-growth medium at ambient temperature and pressure. The synthesis was conducted using plain saline solution (0.85% NaCl) to avoid impurities in the products. X-ray diffraction and transmission electron microscopy indicated that the reduction products were MNPs with a pseudo-spherical shape and 6 ± 2 nm average size. Magnetometry showed that the particles were superparamagnetic with maximum saturation magnetization of 73.8 emu/g, which is comparable to that obtained via chemical synthesis methods. Using less than a quarter of the raw materials employed in a typical chemical co-precipitation method, we obtained a maximum yield of 3.473 g/L (>5-fold increase). These findings demonstrate that our simple and ecofriendly process can help overcome the current barriers for large-scale synthesis of high-purity magnetic nanopowders.

Ferrite-based magnetic materials (ferrites) can be simple iron oxide compounds such as Fe2O3 or Fe3O4, and similar compounds containing other cations besides iron, such as BiFeO3, CaFe 4O7, and BaFe12O19. The solid phase of these compounds generally has varying magnetic properties, depending on the cation (A+m) which is the substitution of the iron cation (Fe+3) in its crystal structure. In addition to the magnetic properties of interest, the compound in question also has strong absorption properties in electromagnetic waves in the frequency interval of 1 - 20 GHz (microwave), which is commonly used in the world of communication and radar technology. With these properties it is possible to develop these materials for electromagnetic shielding and stealth technology applications. As a magnetic element, ferrite material requires a conductive reflector element, to form a “core - shell” or “matrix - filler” system which results in absorption properties. The research that has been developed is in the form of Fe3O4 based micro-nano magnetic powder made from natural ferrite (iron sand). The sythesized of magnetic micro-nano particles using chemical extraction-milling and coprecipitation methods. Morphology of micro-nano particles ferrites has been confirmed by using SEM and TEM. The results of measurements of absorption of microwaves using a Vector Network Analyzer showed that the ferrite nano particle powder has greater absorption power (Reflection Loss < - 20 dB) than micro particle powders with ≥ 99 % absorption in the “X-band” region. The extraction-milling method is simpler and more economical than the chemical coprecipitation method so that it is suitable to be an alternative method for producing large-scale ferrite powder.

We investigated the effect of NiO substitution on the magnetic and physical properties of Co ferrite prepared by the chemical coprecipitation method without postannealing. The chemical coprecipitation compositions were chosen according to the formula (CoO)/sub 1-x/(NiO)/sub x//spl middot/n/2(Fe/sub 2/O/sub 3/), where x varied between 0 and 1.0 and n between 1.0 and 3.0. We found that the single-phase Co-Ni spinel ferrite fine particles could be prepared by the chemical coprecipitation method without postannealing. Optimum magnetic properties were achieved with materials of composition (CoO)/sub 0.5/(NiO)/sub 0.5//spl middot/1.125(Fe/sub 2/O/sub 3/). The typical magnetic and physical properties are saturation magnetization /spl sigma//sub s/ = 56.3 /spl times/ 10/sup -6/ Wb /spl middot/ m/kg (44.8 emu/g), coercivity H/sub cJ/ = 506.9 kA/m (6.37 kOe), Curie temperature T/sub c/ = 557.3/spl deg/C, the lattice constant a = 0.8384 nm, and the average particle size = 30 nm. The rotational hysteresis integral Rh, which is related to the magnetization mechanism of these fine particles, is 1.57. We found that the magnetization mechanism is an incoherent rotation one.

The feasibility of substituting nickel for cobalt in La-Mg-Ni-based hydrogen storage alloys to reduce material costs and improve electrochemical properties is investigated. The series of alloys with the chemical formula La0.75Mg0.25Ni2.7+xCo0.4-xMn0.1Al0.3 (x = 0–0.4) that reflects the gradual substitution of Ni for Co are prepared by chemical co-precipitation plus reduction method. The detailed synthesis process, structure, morphology, electrochemical performance, and kinetic properties of the resulting alloy electrodes are discussed in terms of the variation in substitution amount of Ni for Co. Results reveal that the hydrogen storage alloy substituted with x = 0.1 exhibits the best overall electrochemical performance among all investigated samples, whereas the complete substitution of Ni for Co has no significant effect on electrochemical performance. Based on these results, a mechanism underlying the effect of substituting Ni for Co on the electrochemical performance of the resulting alloy is discussed in detail and effectively verified by conducting three electrochemical kinetic experiments. Complete substitution of Ni for Co is found to be suitable for reducing material costs and improving the overall electrochemical performances of La-Mg-Ni-based hydrogen storage alloys.