Zn Metal Powder Research Articles

ChemInform Abstract: Synthesis of the Hydroxide Cluster [Al13(μ3‐OH)6(μ‐OH)18 (H2O)24]15+ from an Aqueous Solution.

Abstract[Al13(μ3‐OH)6(μ‐OH)18 (H2O)24](NO3)15 is synthesized by treatment of an aqueous solution of Al(NO3)3 with Zn metal powder (Al:Zn = 2:1) at room temperature (55% yield).

STRUCTURAL, OPTICAL AND GAS SENSING PROPERTIES OF ZnO, SnO2 AND ZTO NANOSTRUCTURES

Tetrapods, nanobelts and polyhedron-shape like zinc oxide (ZnO) , tin dioxide (SnO2) nanostructures and ZnO/ZnSnO3/Zn2SnO4 (ZTO) composite functional semiconducting nanostructures have been synthesized successfully by the vapor–solid growth process. XRD analyses showed that ZnO with wurtzite, SnO2 with rutile and zinc stannate (ZnSnO3) and/or dizinc stannate (Zn2SnO4) with polyhedral crystal structure were condensed from the vapor phase when Zn and/or Sn metal powders individually or mixed were used as the starting materials. The driving forces for growth of these nanostructures were found to be vapor density, temperature, pressure and place of deposition from the source materials. Typically, the ZnO nanobelts have lengths of several hundred of nanometers and widths of about 10–15 nm. The average particle size of SnO2 are in the range of about 10–20 nm. Uniform hexagonal-shaped crystals of ZnO/ZnSnO3/Zn2SnO4 composite in the range of 50–300 nm as estimated from TEM images are observed. Based on the TEM, optical absorption and emission studies and the CO gas sensing characteristics of the prepared materials showed good crystal quality implying that the ZnO , SnO2 and ZnO/ZnSnO3/Zn2SnO4 nanostructures may suggest possible applications in optoelectronic devices and chemical gas sensors.

Growth and Characterization of ZnO, SnO2 and ZnO/SnO2 Nanostructures from the Vapor Phase

Zinc oxide (ZnO), tin dioxide (SnO2) and compounds ZnO/SnO2 (ZTO) nanostructures have been synthesized successfully from the vapor phase without a catalyst using three different approaches. XRD analyses showed that ZnO with a wurtzite crystal structure, SnO2 with a rutile crystal structure and zinc stannate (ZnSnO3) and/or dizinc stannate (Zn2SnO4) were condensed from the vapor phase when Zn and/or Sn metal powders or their oxides individually or mixed were used as the starting materials. The formation of either zinc or dizinc stannate was controlled by the Zn/Sn ratio and growth technique. SEM and TEM investigations showed that ZnO grew mainly in the form of wires, rods and belts. These are believed to be originated from the common tetrapod structure of ZnO. While SnO2 grew in the form of tetragonal rods with rectangle-like cross section and nanoparticles, ZTO grew in the form of nanobelts. The final length, width and thickness were as low as 40, 10 and 5 nm, respectively. The driving forces for growth of nanowires, nanorods, nanobelts, and nanoparticles were found to be vapor density or supersaturation, temperature, pressure and location of deposition from the source materials. The optical absorbance and photoluminescence spectra of all samples showed excitonic character at room temperature implying good crystal quality, and high photocurrent properties suggesting possible applications in nanoscaled functional devices such as optoelectronics and gas sensors.

A simple method to prepare ZnO and Al(OH) 3 nanorods by the reaction of the metals with liquid water

Reaction of liquid water with Zn and Al powders and foils have been investigated in the 25–75 °C range. The reaction of Zn metal powder with water in this temperature range yields ZnO nanorods. The diameter of the nanorods decreases slightly with the increase in the reaction temperature, accompanied by an increase in the relative intensity of UV emission band. Zn metal foils also yield ZnO nanorods on reaction with water in the 25–75 °C range. Reaction of Al metal powder or foil with water in the 25–75 °C range yields Al(OH) 3 nanorods. The formation of ZnO and Al(OH) 3 nanorods by the reaction of the metals with water is suggested to occur because of the decomposition of water by the metal giving hydrogen.

Preparation of silver powders in micron size from used photographic films via leaching–cementation technique

The results of a leaching study of used photographic films containing silver with nitric acid are presented. Effect of reaction time, reaction temperature and acid concentration on silver dissolution efficiency was determined. The results obtained show that leaching of about 98% of silver is achieved using − 2 mm spent (used) photographic film size at a reaction temperature of 90 °C for 50 min reaction time with 6% nitric acid concentration. Different solid:liquid ratios of 1:10 to 1:50 g/ml were also studied. Cementation study indicates that practically 100% of silver is deposited with addition of Zn metal powder. SEM photomicrographs show that sphere particles of about 1 μm diameter were obtained.

Nickel-Catalyzed Synthesis of Benzocoumarins: Application to the Total Synthesis of Arnottin I

The ring-opening addition of methyl 2,3-dimethoxy-6-iodobenzoate to oxabenzonorbornadienes followed by cyclization in the presence of NiBr2(dppe) and Zn metal powder in acetonitrile at 80 degrees C to give the corresponding benzocoumarin derivatives is described. This methodology was then applied to the synthesis of natural product arnottin I, first isolated from Xanthoxylum arnottianum Maxim, using protecting group chemistry. After deprotection and subsequent ring closure, arnottin I was obtained in 21% overall yield after six steps starting from catechol.

Growth of Aligned ZnO Nanorods

Growth of high-density and aligned ZnO nanorods on ZnO film substrate has been demonstrated using vapor-transport of thermally evaporated Zn metal powders followed by condensation. Morphological studies show that the nanorods grow preferentially from a hexagonal ZnO base with a uniform hexagonal structure following three-dimensional island-like growth mechanism. Structural and spectroscopic properties clearly indicate that the nanorods are relatively good and defect-free in quality. These nanorods have potential for technological implications.

Structural and optical characterization of ZnO nanocrystalline films deposited by sputtering

Nanocrystalline ZnO thin films were prepared by dc magnetron sputtering in an Ar+O2 gas mixture using two types of targets; one was commercially available zinc metal (purity 99.99%) and the other was pressed Zn metal powder. Influences of the target conditions as well as the oxygen partial pressure on the structural and optical properties were studied. Microstructure of the films was investigated using X-ray diffraction and scanning electron microscopy the optical properties were examined using UV–Visible spectrophotometer. The films deposited from metal target showed better aligned c-axis orientation and exhibited better optical properties compared to films prepared from pressed metal powder target.

Sea-urchin-like ZnO nanostructures on Si by oxidation of Zn metal powders: Structural and optical properties

High-density sea-urchin-like ZnO nanostructures were grown on Si(100) substrates by the oxidation of metallic Zn powders at a low growth temperature without the use of any catalyst or additives. The morphological studies indicated that the grown structures are uniformly dispersed on the substrate and exhibited a sea-urchin-like shape consisting of several thousands of nanorods in one array, each ZnO nanorod of these structures having the diameter of 20–50 nm with the length of 2–4 μm. The high-resolution transmission electron microscopy and selected area electron diffraction patterns showed that the prepared sea-urchin-like ZnO nanostructures were single crystalline with wurtzite hexagonal structure and preferably grown along the [0001] direction. Room temperature Raman scattering and photoluminescence studies found that the as-grown nanostructures have good crystal quality with the hexagonal wurtzite phase.

Effect of Zn and Mn on the Synthesis of Zn2SiO4:Mn2+ Phosphor by SHS

【The synthesis of $Zn_{2}SiO_4:Mn^{2+}$ for PDP green phosphor by SHS(Self-propagating High temperature Synthesis method) was studied. The precursors were well mixed and cold compacted. And then, the green pellet was synthesized at high temperature through self-propagating high temperature zone. Because this reaction uses the heat resulted from the oxidation of Zn metal powder in this system, Zn/ZnO mole ratio is one of the most important reaction variable. Throughout several experiments, the optimal condition of Zn/ZnO mole ratio and Mn concentration are 1.2/0.8 and 0.05mo1e, respectively.】

磁気力顕微鏡（ＭＦＭ）によるＺｎ金属と反応したＳｍ２Ｆｅ１７Ｎ３微細粒子（２‐３μｍ径）の磁区構造の解析 （第１報）

The domain wall motion in the multi-domain particles in Sm2Fe17N3(SFN)powder reacted with Zn metal samples was studied.In the samples, 2 wt.% of SFN particles were homogeneously, isotropically distributed in Zn metal powder, and pressed under 20 MPa, followed by heat-treatment at various temperatures. The saturable multi-domain particles (SMDP) in the sample powders were magnetized into the single-domain state after the pulse magnetization in 5 T. The magnetization reversal in SMDP after magnetization became difficult in the heat-treated samples. The reversal behavior, which can be detected by susceptibility measurements, should be the origin of the enhancement of coercivity. For example, the coercivity (μoH) is about 0.4 T larger in the 623 K treated sample than that of the untreated sample. The direct observation of the domain structures before and after the magnetization in untreated SMDP was also curried out using magnetic force microscopy (MFM).

Production of Zn powder by alkaline treatment of smithsonite Zn–Pb ores

In this work, a production process for Zn powder by alkaline treatment of an oxidized Zn ore, smithsonite (ZnCO 3), was studied. It was found that over 85% of both Zn and Pb, and less than 10% of Al can be leached from the ore when the leaching operation is conducted at over 95°C using 5 M NaOH solution as leaching agent. The dissolution of impurities such as Fe, Ca, etc., was negligible. Leaching of Pb can be improved remarkably with addition of NaCl to the leaching systems. Typical composition of the leach solution is 22–25 g/L Zn, 2.96–3.05 g/L Pb and 0.5–0.7 g/L Al. Zn and Pb contents in the leaching residue were found to be lower than 2.4% and 0.05–0.2%, respectively. Pb present in the leach solution is separated with the addition of sodium sulfide. The Pb-free solution is then used for the electrolysis of metallic Zn using stainless steel electrodes. Zn metal powder with purity higher than 99.5% is obtained. The specific energy for the Zn electrolysis in alkaline leach solution is around 2.4–2.6 kWh/kg Zn, which is lower than the energy consumption of 3.3 kWh/kg Zn required in the conventional process of Zn electrolysis in acidic sulfate electrolytes. The process developed is considered to be cost-effective, simple and easy to be operated and managed, and the flowsheet for the production of Zn from ores is presented. It is proposed that ores be broken into particles smaller than 0.1–0.5 mm. Then, leached with 5 M NaOH solution at a 90–95°C temperature for 1.5 h at a phase ratio [NaOH solution added (ml) to the ore leached (g)] of 6–7. After filtration, the leach solution is subjected to electrolysis for the production of metallic Zn after Pb is separated by sodium sulfide. The NaOH solution is recycled to the next leaching operation after most of the Zn is electrowon. To save energy and keep heat loss minimal, all operations can be conducted in an adiabatic environment, including leaching, filtration and electrolysis. Loss of NaOH was estimated to be less than 50 g for the production of 1 kg of Zn, assuming that most NaOH left in the leaching residues and precipitates of lead sulfide could be recovered by washing with dilute NaOH solution and water. However, loss of NaOH is dependent on the type and composition of the ores. The presence and leaching of silicates, carbonates and phosphates in ores would increase the loss of NaOH and deteriorate filtration of leach residues in the alkaline solutions. Therefore, most of the operational cost for this process comprises the consumption of electricity for electrolysis, NaOH, and energy required for heating.

Effect of some transition metals on interactions of simple ammonium carboxylates with hydrogen peroxide

Reactions of equimolar mixtures of copper (Cu), zinc (Zn) metal powders with either ammonium formate or acetate or tetrabutyl ammonium acetate (1:1:2) in excess hydrogen peroxide (H2O2) at ambient conditions results in decarboxylation yielding mixed metal oxide [Cu, ZnO2·H2O], while the corresponding reaction with ammonium succinate results in formation of mixed metal peroxo carbonate [Cu, Zn(O22−)(CO3)(H2O)2]. Interestingly, in all the above mentioned carboxylates, the corresponding reactions in the presence of H2O2 and imidazole (HIm) results in formation of HIm adducts of mixed metal peroxo carbonates [Cu, Zn(O22−)(CO3)(HIm)x(H2O)2]. It is noteworthy to mention that all the above mentioned reactions in presence of either Cu or Zn powder alone, did not give any homogeneous reaction product, and instead the metal powder remained undissolved. Similarly, it is very significant to observe that the reaction of sodium salts of the above mentioned carboxylic acids with H2O2 in presence of either Cu-Zn mixture or Cu-Zn-HIm mixture did not give any decomposed products and instead the metal powders remained undissolved. Hence this work is of significance as it reports for the first time, the profound effect of the presence of both ammonium ion and carboxylic group in simple carboxylates and its reaction with H2O2 in the presence of Cu-Zn mixture. The new mixed metal peroxo carbonates and the imidazole adducts isolated from the above mentioned reaction systems were characterised by chemical, elemental and thermogravimetric analyses, ESR, electronic and IR spectral studies.

Synthesis and structure determination of complex zinc hydrides part 1: Dipotassiumtetrahydridozincate(II): K 2[ZnH 4

K 2ZnH 4 and its deuteride were prepared by a solid state reaction between stoichiometric amounts of KH (KD) and Zn metal powders at 650 K and 80 bar hydrogen (deuterium) pressure, and characterized by X-ray and neutron powder diffraction. They crystallize with the orthorhombic β-K 2SO 4 structure type, space group Pnma (No. 62), Z = 4, cell parameters a = 7.7601(5), b = 5.8636(4), c = 10.2832(7) A ̊ (hydride); a = 7.7579(4), b = 5.8631(3), c = 10.2813(5) A ̊ (deuteride). Zinc is tetrahedrally coordinated by deuterium with bond distances in the range of 1.632(4) to 1.665(4) Å and bond angles in the range 108.0° to 112.7°. K 2ZnD 4 decomposes in 1 bar D 2 at 580(10) K to KD and Zn.

The solubility of uranium(IV) hydrous oxide in sodium hydroxide solutions under reducing conditions

The solubility of hydrous UO 2 in sodium hydroxide solutions containing sodium dithionite and/or Zn metal powder as reductants has been measured. The results provide no firm evidence for any amphoteric behavior of U(IV) but do set an upper limit of K ≤ 2 x 10 −23 for the hypothetical reaction: ▪ The results provide no evidence for such a reaction.