Indium contamination

A.R. Schlatmann, D.W. Floet, A. Hilberer, F. Garten, P.J.M. Smulders, T.M. Klapwijk, and G. Hadziioannou, Indium contamination from the indium tin-oxide electrode in polymer light-emitting diodes, Appl. Phys. Lett., 69 1764—1766, 1996. 

Some metals used as metallic coatings are considered nontoxic, such as aluminum, magnesium, iron, tin, indium, molybdenum, tungsten, titanium, tantalum, niobium, bismuth, and the precious metals such as gold, platinum, rhodium, and palladium. However, some of the most important poUutants are metallic contaminants of these metals. Metals that can be bioconcentrated to harmful levels, especially in predators at the top of the food chain, such as mercury, cadmium, and lead are especially problematic. Other metals such as silver, copper, nickel, zinc, and chromium in the hexavalent oxidation state are highly toxic to aquatic Hfe (37,57—60). 

Ueno et al. [172] observed that CuInSe2/Ti with a composition close to the stoichiometric ratio (slight excess of metallic components) could be deposited exclusively at a specific potential value (-0.8 V vs. SCE) from a pH 1 bath of uncom-plexed precursors at 50-55 A positive shift in the potential was seen to result in the co-deposition of a Cu3Sc2 phase (umangite), while a negative shift led to contamination by metallic indium. On the basis of measured electrolysis charge, the overall reaction of the optimum cathodic process was considered to involve the transfer of 13 electrons per mole of the product ... 

The trimeric indium antimonide single-source precursor [Et2InSb(SiMe3)2]3, prepared from Et2InCl and Sb(SiMe3)3, was shown in a preliminary study to form InSb nanocrystals (average particle size 10 nm) by solid-state thermolysis at 400 °C under a static vacuum. However, the particles were contaminated with elemental indium.399... 

Light hydrocarbons were extracted, isolated, and characterized chro-matographically following techniques of Dunton and Hunt (2). Sediment studies require no special modifications other than more stringent precautions to avoid contamination because of the lower concentrations in sediments than rocks. Figures 2 and 3 are both based on analyses from the same technique, but in Figure 3 the chromatograms were produced as part of a routine, automatic operation. Extracts are encapsulated in indium and then introduced into the heated injection block presentation is somewhat compressed, but results are comparable. 

Removal of contamination by ion bombardment with inert gas ions, followed by annealing. This method can be applied to either single or poly-crystalline materials and has been found to be effective for the compound indium antimonide having a melting point of 525°C as well as for more refractory materials, ft has also been found to be effective in removing a monolayer of carbon from nickel and silicon crystals. 

The increased ionization energies of the heavier transition metals should not be unexpected by anyone who has had a modicum of laboratory experience with any of these elements. Although none of the coinage metals is very reactive, gold has a well-deserved reputation for being less reactive than copper or silver iron, cobalt, and nickel rust and corrode, but osmium, indium, and platinum are noble and unreaclive and therefore are used in jewelry platinum wires are the material of choice fior flame tests without contamination and one generates hydrogen with zinc and simple adds, not with mercury. 

The technique involves the use of an inductively coupled plasma to convert trace elements to their gaseous ions followed by analysis of these ions by mass spectrometry. Examples include the quantitative analysis of trace copper by isotope dilution and the analysis of trace contaminants in boron, indium phosphide and reagent acids. 

A good reference material has a number of desirable properties including a well-documented value, avmlability in a suitable form for analysis, homogeneity, stability, low toxicity, and traceability to a national reference laboratory (NRL). In traditional DSC and TMA, metals like indium, tin, and zinc meet these criteria. These metals are not suitable for temperature calibration for localised thermal analysis, however, as they may contaminate the probe tip thus changing its resistance and defeating the object of calibration.. 

When metallic indium, although contaminated, was prepared, Richter submitted the samples to the Paris Academy of Sciences in 1867 and estimated their value at 800 pounds sterling which was quite a lot of money at the time. 

Cast alloys must be made from at least 99.99% purity zinc ingot to comply with the standards of the American Society for Testing and Materials (ASTM B6) and the International Organization for Standardization (ISO 752) a standard is in preparation by the Comit Europeen de Normalisation (CEN European Committee for Standardization). The harmful impurities, which occur naturally in zinc or as contaminants in the other alloying ingredients, are lead, tin, cadmium, indium, and thallium. These impurities are limited by specification higher contents than specified may make the alloys susceptible to intergranular corrosion, particularly when exposed to warm, moist environments. 

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