Method of preparing zinc orthotitanate pigment

Zinc orthotitanate suitable for use as a pigment for spacecraft thermal control coatings is prepared by heating a slightly zinc deficient reaction mixture of precipitated oxalates of zinc and titanium. The reaction mixture can be formed by coprecipitation of zinc and titanium oxalates from chloride solution or by mixing separately precipitated oxalates. The mixture is first heated to 400 to 600 C to remove volatiles and is then rapidly heated at 900 to 1200 C. Zinc orthotitanate produced by this method exhibits the very fine particle size needed for thermal control coatings as well as stability in a space environment

Chromium, nickel and zinc induced histopathological alterations in the gill of Indian common carp Labeo rohita (Ham.)

Degenerative histopathalogical alterations were seen in gills due to chronic exposure of the fish, Labeo rohita to chlorides of chromium, nickel and zinc for 30 days. However, more severe degenerative changes were observed in case of zinc chloride exposed fish than nickel chloride and chromium chloride treated fishes, indicating more toxic nature of zinc chloride. Mucus secretion over the gill lamellae was seen prominently in all the experimental fishes. However, in zinc chloride treated fish there was excessive mucus secretion after ten days of exposure andafter thirty days, epithelial lifting was seen. In chromium chloride and nickel chloride treated fishes there was basal hyperplasia, which indicated compensatory mechanism in ion regulation to adjust with the toxic stress

Hydrometallurgy of the delta sulfide ores, first stage report

This report presents the results of hydrometallurgical research carried out from September 16, 1985 to June 30, 1986 on metals recovery from complex sulfide ores from the Delta deposit near Tok, Alaska. The leaching characteristics performed for 6 different ore samples indicate that the most valuable components form the following order: Zn > Au > Pb > Ag > Cu > So. Further study demonstrates that direct leaching of the ore is effective both in chloride as well as in sulfate oxidizing solutions coupled with separating of leached solid components by flotation. Three variants of the ore processing with ferric chloride or fenic sulfate leaching are analyzed: one flowsheet with direct ore leaching in ferric chloride solution followed by leaching-flotation step, with subsequent zinc separation in a solvent extraction step and electrolysis in chloride solution; and two flowsheets of direct ore leaching with ferric sulfate solution followed by a leaching-flotation step, with zinc sulfate electrolysis and other metals recovery in chloride leaching sreps. In two last flowsheets silver is recovered during the chloride leaching steps and gold h m flotation products during the cyanide leaching. Preliminary economic and technical evaluation is presented. The engineering study on apparatus for the fast leaching- flotation processing and on better accumulation of gold and silver in one semi-product are concluded for the next year of research

Optimization of zinc electrodeposition from zinc-air cell discharge performance

Porous zinc electrodes were prepared from an acidic, chloride electrolytic bath for application in zinc-air microbattery. The aim is to produce a high specific surface area zinc coating in order to obtain high storage capacity and high limiting current density of the microbattery. The electrolytic bath consists of zinc chloride as the metal source and ammonium chloride as the supporting electrolyte. The concentration of the supporting electrolyte was varied from 1 to 6 M, while the concentration of zinc chloride was fixed at 2 M. The electrodeposition was performed at a constant current density of 100mAcm-2. No electrolyte agitation was attempted. SEM micrographs revealed unique cross-stitch porous network morphology of zinc electrodeposits. As the ammonium chloride concentration increases, flake microstructure appeared and later becomes predominant. A thin alkaline zinc-air cell was fabricated utilizing the various qualities of the zinc electrodeposits. The effect of the qualities of the zinc electrodeposits on the cell discharge performance was monitored. The zinc-air microbattery of 1 cm2 area x ca. 305 µm thick was able to produce a maximum limiting current density of 35 mA cm-2 and possessed a specific capacity of 327 mAh g-

Passivation studies on Cd0.6Zn0.4Te films using CdCl2, MgCl2 and ZnCl2 for top cell application in a multijunction solar cell

2018 Summer.Includes bibliographical references.Passivation treatment with the chloride compounds is an important step in the fabrication of II-VI solar cells for improving the device performance. In cadmium telluride solar cells, cadmium chloride passivation treatment incorporates chlorine along the grain boundaries and helps in recrystallization, grain growth, removal of stacking faults and doping grain boundaries as n-type. In cadmium zinc telluride solar cells, the retention of zinc after the cadmium chloride passivation treatment is one of the challenges incurred in fabricating the top cell in a multijunction solar cell. During the passivation treatment, the loss of zinc occurs in the form of volatile zinc chloride compound. The depletion or complete loss of zinc reduces the higher band gap ternary alloy into lower band gap binary compound of CdTe. This impedes the purpose of fabricating a high band gap top cell in a multijunction solar cell. The focus of this study is on passivating Cd0.6Zn0.4Te (CdZnTe) films using three different chloride compounds separately and understanding the effects by studying the material properties of the passivated films and electrical performance of the fabricated devices. In the preliminary experiments, CdZnTe films were deposited by RF sputtering from a single target. Initial characterization of CdZnTe films deposited on plain glass indicated that the films had a strong preferred orientation along {111} plane with a band gap of ~1.72eV. In the cadmium chloride passivation treatment, loss of zinc from the surface and no chlorine along the grain boundaries was observed from transmission electron microscope images and X ray diffraction measurements. No loss of zinc was observed after the magnesium chloride and zinc chloride passivation treatments. Increase in the grain size of the CdZnTe films after magnesium chloride treatment and decrease of the preferred orientation after zinc chloride treatment were the benefits of the individual passivation treatments. Modifying the test structure by adding a cadmium telluride film as a capping layer on the back of RF sputtered CdZnTe and then carrying out the cadmium chloride passivation treatment helped in retaining the zinc. Heavy diffusion of zinc into cadmium sulphide due to cadmium telluride deposition at high temperature and difficulty to isolate the photo current generated by cadmium telluride were few drawbacks of this test structure. Based on the insights gained from the preliminary experiments, two sets of experiments were conducted. In the first set, cadmium sulphide cap as a barrier was deposited on the back of RF sputtered CdZnTe and co-sublimated cadmium telluride and zinc films with a band gap of 1.72 eV. The bulk composition was maintained after the cadmium chloride passivation treatment in the films deposited by both the methods. However the device performance of co-sublimated films was better than the RF sputtered CdZnTe devices. The transmission electron image obtained from the cross section of co-sublimated film fitted with cadmium sulphide cap and then treated with cadmium chloride showed presence of chlorine along the grain boundaries. The zinc chloride passivation treatments with higher substrate temperature compared to the source were the second set of experiments. The zinc loss from RF sputtered CdZnTe films after the cadmium chloride treatment did not occur. The fabricated devices exhibited diode like behavior. The images under scanning electron microscopy showed that the grain size did not increase after the zinc chloride treatment

A Study of the Hoesch-Houben Synthesis in the Preparation of Aromatic Ketimines and Hydroxy-Phenyl Iminoesters

This synthesis involves the condensation of a phenol with a nitrile (aliphatic or aromatic). It is effected by the passage of dry hydrogen chloride through their solution in anhydrous ether, with or without the addition of dry zinc chloride. Anhydrous aluminum chloride was substituted for zinc chloride in some cases

Addition and cycloaddition reactions of allenyl cations with various cycloalka-1,3-dienes

Allenyl cations , generated from propargyl chlorides and zinc chloride give monocyclic adducts or [3+4] and [2+4] cycloaddition products with various cycloalka-1,3-dienes. The mode of addition depends on R and the ring size of the 1,3-dienes

Morphology and Properties of Zn-Al-TiO2 Composite on Mild Steel

The influence of TiO2 composite and dispersed pure Al particle on zinc alloy electrodeposited on mild steel was studied from chloride bath solution.Microstructural and mechanical properties of the alloy were investigated. The structure, surface morphology, and surface topography of the deposited alloys were characterized by scanning electron microscopy (SEM) and atomic force microscope (AFM).In addition, hardness of the coated alloys was measured. It was found that the obtained Zn-Al-TiO2 alloyexhibited more preferred surface morphology and mechanical strength compared tothe substrate. The result shows the existence of interaction between TiO2 compounds and zinc alloy particulate. It also exhibited well bright dominate zinc coating on steel surface