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20 décembre 2011 2 20 /12 /décembre /2011 02:28

Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Similar to zinc, it prefersoxidation state +2 in most of its compounds and similar to mercury it shows a low melting point compared to transition metals.Sony VAIO VGN-G118CN Battery

Cadmium and its congeners are not always considered transition metals, in that they do not have partly filled d or f electron shells in the elemental or common oxidation states. The average concentration of cadmium in the Earth's crust is between 0.1 and 0.5 parts per million (ppm).Sony VAIO VGN-G118GN/B Battery

It was discovered in 1817 simultaneously by Stromeyer and Hermann, both in Germany, as an impurity in zinc carbonate.

Cadmium occurs as a minor component in most zinc ores and therefore is a byproduct of zinc production. It was used for a long time as a pigment and for corrosion resistant plating on steel while cadmium compounds were used to stabilizeplastic.Sony VAIO VGN-G118GN/T Battery

With the exception of its use in nickel–cadmium batteries and cadmium telluride solar panels, the use of cadmium is generally decreasing in its other applications. These declines have been due to competing technologies, cadmium’stoxicity in certain forms and concentration and resulting regulations.Sony VAIO VGN-G118TN/B Battery

Although cadmium has no known biological function in higher organisms, a cadmium-dependent carbonic anhydrase has been found in marine diatoms.

Physical properties

Cadmium is a soft, malleable, ductile, bluish-white divalent metal. It is similar in many respects to zinc but formscomplex compounds.Sony VAIO VGN-G118TN/S Battery

Unlike other metals, cadmium is resistant to corrosion and as a result it is used as a protective layer when deposited on other metals. As a bulk metal, cadmium is insoluble in water and is not flammable; however, in its powdered form it may burn and release toxic fumes.Sony VAIO VGN-G11VN/T Battery

Chemical properties

Although cadmium usually has an oxidation state of +2, it also exists in the +1 state. Cadmium and its congeners are not always considered transition metals, in that they do not have partly filled d or f electron shells in the elemental or common oxidation states.Sony VAIO VGN-G11VN/TC Battery

Cadmium burns in air to form brown amorphous cadmium oxide (CdO); the crystalline form of this compound is a dark red which changes color when heated, similar to zinc oxide. Hydrochloric acid, sulfuric acid and nitric acid dissolve cadmium by forming cadmium chloride (CdCl2), cadmium sulfate (CdSO4), or cadmium nitrate (Cd(NO3)2).Sony VAIO VGN-G11XN/B Battery

The oxidation state +1 can be reached by dissolving cadmium in a mixture of cadmium chloride and aluminium chloride, forming the Cd22+ cation, which is similar to the Hg22+ cation in mercury(I) chloride. 

Naturally occurring cadmium is composed of 8 isotopes. Two of them are naturally radioactive, and three are expected to decay but have not been experimentally confirmed to do so.Sony VAIO VGN-G1AAPS Battery

The two natural radioactive isotopes are 113Cd (beta decay, half-life is 7.7 × 1015 years) and 116Cd (two-neutrino double beta decay, half-life is 2.9 × 1019 years). The other three are 106Cd, 108Cd (both double electron capture), and114Cd (double beta decay); only lower limits on their half-life times have been set.Sony VAIO VGN-G1AAPSA Battery

At least three isotopes – 110Cd, 111Cd, and 112Cd – are stable. Among the isotopes that do not occur naturally, the most long-lived are 109Cd with a half-life of 462.6 days, and 115Cd with a half-life of 53.46 hours. All of the remaining radioactive isotopes have half-lives that are less than 2.5 hours, and the majority of these have half-lives that are less than 5 minutes.Sony VAIO VGN-G1AAPSB Battery

Cadmium has 8 known meta states, with the most stable being 113mCd (t½ = 14.1 years), 115mCd (t½ = 44.6 days), and 117mCd (t½= 3.36 hours).

The known isotopes of cadmium range in atomic mass from 94.950 u (95Cd) to 131.946 u (132Cd).Sony VAIO VGN-G1AAPSC Battery

For isotopes lighter than 112 u, the primary decay mode is electron capture and the dominant decay product is element 47 (silver). Heavier isotopes decay mostly through beta emission producing element 49 (indium).

One isotope of cadmium, 113Cd, absorbs neutrons with very high probability if they have an energy below the cadmium cut-off and transmits them otherwise.Sony VAIO VGN-G1ABNS Battery

The cadmium cut-off is about 0.5 eV. Neutrons with energy below the cutoff are deemed slow neutrons, distinguishing them from intermediate and fast neutrons.

Cadmium is created via the long s-process in low-medium mass stars with masses of 0.6 to 10 solar masses, which lasts thousands of years. It requires a silver atom to capture a neutron and then undergo beta decay.Sony VAIO VGN-G1KAP Battery

Cadmium (Latin cadmia, Greek ??????? meaning "calamine", a cadmium-bearing mixture of minerals, which was named after the Greek mythological character, ?????? Cadmus, the founder of Thebes) was discovered simultaneously in 1817 by Friedrich Stromeyer and Karl Samuel Leberecht Hermann, both in Germany, as an impurity in zinc carbonate.Sony VAIO VGN-G1KBN Battery

Stromeyer found the new element as an impurity in zinc carbonate (calamine), and, for 100 years, Germany remained the only important producer of the metal. The metal was named after the Latin word for calamine, since the metal was found in this zinc compound.Sony VAIO VGN-G1KBNA Battery

Stromeyer noted that some impure samples of calamine changed color when heated but pure calamine did not. He was persistent in studying these results and eventually isolated cadmium metal by roasting and reduction of the sulfide. The possibility to use cadmium yellow as pigment was recognized in the 1840s but the lack of cadmium limited this application.Sony VAIO VGN-G1LAP Battery

Even though cadmium and its compounds may be toxic in certain forms and concentrations, theBritish Pharmaceutical Codex from 1907 states that cadmium iodide was used as a medication to treat "enlarged joints, scrofulous glands, and chilblains".

In 1927, the International Conference on Weights and Measures redefined the meter in terms of a red cadmium spectral line (1 m = 1,553,164.13 wavelengths). This definition has since been changed (see krypton).Sony VAIO VGN-G1LBN Battery

After the industrial scale production of cadmium started in the 1930s and 1940s, the major application of cadmium was the coating of iron and steel to prevent corrosion; in 1944, 62% and in 1956, 59% of the cadmium in the United States was for coating.Sony VAIO VGN-G218LN/T Battery

In 1956, 24% of the cadmium used within the United States was used for the second application, which was for red, orange and yellow pigments based on sulfides and selenides of cadmium. The stabilizing effect of cadmium-containing chemicals like the carboxylates cadmium laureate and cadmium stearate on PVC led to an increased use of those compounds in the 1970s and 1980s.Sony VAIO VGN-G218N/B Battery

The use of cadmium in applications such as pigments, coatings, stabilizers and alloys declined due to environmental and health regulations in the 1980s and 1990s; in 2006, only 7% of total cadmium consumption was used for plating and coating and only 10% was used for pigments.Sony VAIO VGN-G21XP/B Battery

The decrease in consumption in other applications was made up by a growing demand of cadmium in nickel-cadmium batteries, which accounted for 81% of the cadmium consumption in the United States in 2006.

Occurrence

Cadmium makes up about 0.1 ppm of the Earth's crust. Compared with the more abundant zinc with 65 ppm cadmium is rare.Sony VAIO VGN-G2AANS Battery

No significant deposits of cadmium-containing ores are known. Greenockite (CdS), the only cadmium mineral of importance, is nearly always associated with sphalerite (ZnS). This association is caused by the geochemical similarity between zinc and cadmium which makes geological separation unlikely.Sony VAIO VGN-G2AAPS Battery

As a consequence, cadmium is produced mainly as a byproduct from mining, smelting, and refining sulfidic ores of zinc, and, to a lesser degree, lead and copper. Small amounts of cadmium, about 10% of consumption, are produced from secondary sources, mainly from dust generated by recycling iron and steel scrap.Sony VAIO VGN-G2AAPSA Battery

Production in the United States began in 1907, but it was not until after World War I that cadmium came into wide use. One place where metallic cadmium can be found is the Vilyuy River basin in Siberia.

Rocks mined to produce phosphate fertilizers contain varying amounts of cadmium, leading to a cadmium concentration of up to 300 mg/kg in the produced phosphate fertilizers and thus in the high cadmium content in agricultural soils.Sony VAIO VGN-G2AAPSB Battery

Coal can contain significant amounts of cadmium, which ends up mostly in the flue dust.

Production

The British Geological Survey reports that in 2001, China was the top producer of cadmium, producing almost one-sixth of the world share, closely followed by South Korea and Japan.Sony VAIO VGN-G2AAPSC Battery

Cadmium is a common impurity in zinc ores, and it is most often isolated during the production of zinc. Some zinc ores concentrates from sulfidic zinc ores contain up to 1.4% of cadmium. In 1970s, the output of cadmium was 6.5 pounds per ton of zinc.Zinc sulfide ores are roasted in the presence of oxygen, converting the zinc sulfide to the oxide.Sony VAIO VGN-G2KAN Battery

Zinc metal is produced either by smelting the oxide with carbon or by electrolysis in sulfuric acid. Cadmium is isolated from the zinc metal by vacuum distillation if the zinc is smelted, or cadmium sulfate is precipitated out of the electrolysis solution.

Applications

Cadmium has many common industrial uses as it is a key component in battery production, is present in cadmium pigments,coatings, and is commonly used in electroplating.Sony VAIO VGN-G2KANA Battery

Batteries

In 2009, 86% of cadmium was used in batteries, predominantly in rechargeable nickel-cadmium batteries. Nickel-cadmium cells have a nominal cell potential of 1.2 V. The cell consists of a positive nickel hydroxide electrode and a negative cadmium electrode plate separated by an alkaline electrolyte (potassium hydroxide) . Sony VAIO VGN-G2KBNA Battery

The European Union banned the use of cadmium in electronics in 2004 with several exceptions but reduced the allowed content of cadmium in electronics to 0.002%.

Electroplating

Cadmium electroplating, consuming 6% of the global production, can be found in the aircraft industry due to the ability to resistcorrosion when applied to steel components.Sony VAIO VGN-NR160E/S Battery

This coating is passivated by the usage of chromate salts. A limitation of cadmium plating is hydrogen embrittlement of high-strength steels caused by the electroplating process. Therefore, steel parts heat-treated to tensile strength above 1300 MPa (200 ksi) should be coated by an alternative method (such as special low-embrittlement cadmium electroplating processes or physical vapor deposition).Sony VAIO VGN-NR160E/T Battery

In addition, titanium embrittlement caused by cadmium-plated tool residues resulted in banishment of these tools (along with routine tool testing programs to detect any cadmium contamination) from the A-12/SR-71 and U-2 programs, and subsequent aircraft programs using titanium.Sony VAIO VGN-NR160E/W Battery

Nuclear fission

Cadmium is used as a barrier to control neutrons in nuclear fission. The pressurized water reactor designed by Westinghouse Electric Company uses an alloy consisting of 80% silver, 15% indium, and 5% cadmium.

Compounds

Cadmium oxide is used in black and white television phosphors and in the blue and green phosphors for color television picture tubes.Sony VAIO VGN-NR180E/S Battery

Cadmium sulfide (CdS) is used as a photoconductive surface coating for photocopier drums.

In paint pigments, cadmium forms various salts, with CdS being the most common. This sulfide is used as a yellow pigment. Cadmium selenide can be used as red pigment, commonly called cadmium red.Sony VAIO VGN-NR180E/T Battery

To painters who work with the pigment, cadmium yellows, oranges, and reds are the most brilliant and long-lasting colors to use. In fact, during production, these colors are significantly toned down before they are ground with oils and binders, or blended into watercolors, gouaches, acrylics, and other paint and pigment formulations.Sony VAIO VGN-NR290E/S Battery

Since these pigments are potentially toxic, it is recommended to use a barrier cream on the hands to prevent absorption through the skin when working with them even though the amount of cadmium absorbed into the body through the skin is usually reported to be less than 1%.Sony VAIO VGN-NR290E/T Battery

In PVC, cadmium was used as heat, light, and weathering stabilizers. Currently, cadmium stabilizers have been completely replaced with barium-zinc, calcium-zinc and organo-tin stabilizers. Cadmium is used in many kinds of solder and bearing alloys, due to a low coefficient of friction and fatigue resistance.Sony VAIO VGN-NR298E/S Battery

It is also found in some of the lowest-melting alloys, such asWood's metal.

Laboratory uses

Helium–cadmium lasers are a common source of blue-ultraviolet laser light. They operate at either 325 or 422 nm and are used influorescence microscopes and various laboratory experiments.Cadmium selenide quantum dots emit bright luminescence under UV excitation (He-Cd laser, for example).Sony VAIO VGN-NR460E/L Battery

The color of this luminescence can be green, yellow or red depending on the particle size. Colloidal solutions of those particles are used for imaging of biological tissues and solutions with a fluorescence microscope.

Cadmium is a component of some compound semiconductors, such as cadmium sulfide, cadmium selenide, and cadmium telluride, which can be used for light detection or solar cells.Sony VAIO VGN-NR460E/P Battery

HgCdTe is sensitive to infrared light and therefore may be utilized as an infrared detector or switch for example in remote control devices.

In molecular biology, cadmium is used to block voltage-dependent calcium channels from fluxing calcium ions, as well as inhypoxia research to stimulate proteasome-dependent degradation of Hif-1?.Sony VAIO VGN-NR498E/L Battery

Biological role

Cadmium has no known useful role in higher organisms. A role for cadmium in lower life-forms has recently been found. A cadmium-dependent carbonic anhydrase has been found in marine diatoms. Cadmium performs the same function as zinc in other anhydrases, but the diatoms live in environments with very low zinc concentrations and thus they utilize cadmium to perform functions normally carried out by zinc.Sony VAIO VGN-NR498E/S Battery

The discovery relied on the use of X-ray absorption fluorescence spectroscopy (XAFS).

The highest concentration of cadmium has been found to be absorbed in the kidneys of humans, and up to about 30 mg of cadmium is commonly inhaled throughout childhood and adolescence.

Cadmium can be used to block calcium channels in chicken neurons.Sony VAIO VGN-NR498E/T Battery

Safety

The most dangerous form of occupational exposure to cadmium is inhalation of fine dust and fumes, or ingestion of highly soluble cadmium compounds. Inhalation of cadmium-containing fumes can result initially in metal fume fever but may progress to chemical pneumonitis, pulmonary edema, and death.Sony VAIO VGN-NR498E/W Battery

Cadmium is also an environmental hazard. Human exposures to environmental cadmium are primarily the result of fossil fuel combustion, phosphate fertilizers, natural sources, iron and steel production, cement production and related activities, nonferrous metals production, and municipal solid waste incineration.Sony VAIO VGN-NR50 Battery

However, there have been a few instances of general population toxicity as the result of long-term exposure to cadmium in contaminated food and water. In the decades leading up toWorld War II, Japanese mining operations contaminated the Jinz? River with cadmium and traces of other toxic metals.Sony VAIO VGN-NR50B Battery

As a consequence, cadmium accumulated in the rice crops growing along the riverbanks downstream of the mines. Some members of the local agricultural communities consuming the contaminated rice developed itai-itai disease and renal abnormalities, including proteinuria and glucosuria.Sony VAIO VGN-NR51 Battery

The victims of this poisoning were almost exclusively post-menopausal women with low iron and other mineral body stores. Similar general population cadmium exposures in other parts of the world have not resulted in the same health problems because the populations maintained sufficient iron and other mineral levels.Sony VAIO VGN-NR51B Battery

Thus, while cadmium is a major factor in the itai-itai disease in Japan, most researchers have concluded that it was one of several factors. Cadmium is one of six substances banned by the European Union's Restriction on Hazardous Substances (RoHS) directive, which bans certain hazardous substances in electrical and electronic equipment but allows for certain exemptions and exclusions from the scope of the law.Sony VAIO VGN-NR52 Battery

Although some studies linked exposure to cadmium with lung and prostate cancer, there is still a substantial controversy about the carcinogenicity of cadmium. More recent studies suggest that arsenic rather than cadmium may lead to the increased lung cancer mortality rates.Sony VAIO VGN-NR52B Battery

Furthermore, most data regarding the carcinogenicity of cadmium rely on research confounded by the presence of other carcinogenic substances.

Tobacco smoking is the most important single source of cadmium exposure in the general population. It has been estimated that about 10% of the cadmium content of a cigarette is inhaled through smoking.Sony VAIO VGN-NR71B Battery

The absorption of cadmium from the lungs is much more effective than that from the gut, and as much as 50% of the cadmium inhaled via cigarette smoke may be absorbed.

On average, smokers have 4–5 times higher blood cadmium concentrations and 2–3 times higher kidney cadmium concentrations than non-smokers.Sony VAIO VGN-NR71B2 Battery

Despite the high cadmium content in cigarette smoke, there seems to be little exposure to cadmium from passive smoking. No significant effect on blood cadmium concentrations has been detected in children exposed to environmental tobacco smoke.

Cadmium exposure is a risk factor associated with early atheroslcerosis and hypertension, which can both lead to cardiovascular disease.Sony VAIO VGN-NR72B Battery

Regulations

Due to the adverse effects on the environment and human health, the supply and use of cadmium is restricted in Europe under the REACH Regulation.

Product recalls

In May 2006, a sale of the seats from Arsenal F.C.'s old stadium, Highbury in London, England was cancelled after the seats were discovered to contain trace amounts of cadmium.Sony VAIO VGN-NS10E/S Battery

Reports of high levels of cadmium use in children's jewelry in 2010 led to a US Consumer Product Safety Commission investigation.The U.S. CPSC issued specific recall notices for cadmium content applying to jewelry sold by Claire's and Wal-Mart stores. Sony VAIO VGN-NS10J/S Battery

In June 2010 McDonald's voluntarily recalled more than 12 million promotional "Shrek Forever After 3D" Collectable Drinking Glasses due to concerns over cadmium levels in paint pigments used on the glassware. The glasses were manufactured by Arc International, of Millville, NJ, USA.Sony VAIO VGN-NS10L/S Battery

Indium is a chemical element with the symbol In and atomic number 49. This rare, very soft, malleable and easily fusible post-transition metal is chemically similar to gallium and thallium, and shows the intermediate properties between these two.Sony VAIO VGN-NS110E/L Battery

Indium was discovered in 1863 and named for the indigo blue line in its spectrum that was the first indication of its existence in zinc ores, as a new and unknown element. The metal was first isolated in the following year. Zinc ores continue to be the primary source of indium, where it is found in compound form.Sony VAIO VGN-NS110E/S Battery

Very rarely the element can be found as grains of native (free) metal, but these are not of commercial importance.

Indium's current primary application is to form transparent electrodes from indium tin oxide in liquid crystal displays andtouchscreens, and this use largely determines its global mining production.Sony VAIO VGN-NS110E/W Battery

It is widely used in thin-films to form lubricated layers (during World War II it was widely used to coat bearings in high-performance aircraft). It is also used for making particularly low melting point alloys, and is a component in some lead-free solders.

Indium is not known to be used by any organism.Sony VAIO VGN-NS115N/S Battery

In a similar way to aluminium salts, indium(III) ions can be toxic to the kidney when given by injection, but oral indium compounds do not have the chronic toxicity of salts of heavy metals, probably due to poor absorption in basic conditions. Radioactive indium-111 (in very small amounts on a chemical basis) is used innuclear medicine tests, as a radiotracer to follow the movement of labeled proteins and white blood cells in the body.Sony VAIO VGN-NS11ER/S Battery

Physical

Indium is a very soft, silvery-white, relatively rare true metal with a bright luster. When it is bent, indium emits a high-pitched "cry".Like gallium, indium is able to wetglass. Indium has a low melting point, compared to those of most other metals, 156.60 °C (313.88 °F);Sony VAIO VGN-NS11E/S Battery

it is higher than that of its lighter homologue, gallium, but lower than that of the heavier homologue, thallium. Its boiling point is, however, moderate, being 2072 °C (3762 °F), which is higher than that of thallium, but lower than that of gallium, showing opposition to melting points trend.Sony VAIO VGN-NS11J/S Battery

The density of indium, 7.31 g·cm?3, is also higher than that of gallium, but lower than that of thallium.

Indium atom has 49 electrons, having electronic configuration [Kr]4d105s25p1. In its compounds, indium most often loses its three outermost electrons, becoming indium(III) ions, In3+, but in some cases the pair of 5s-electrons can stay within the atom,Sony VAIO VGN-NS11L/S Battery

indium thus oxidized only to indium(I), In+. This happens due to inert pair effect, which occurs because of stabilization of 5s-orbital due to relativistic effects, which are stronger closer to the bottom of the periodic table. Thallium shows an even stronger effect, making oxidation to thallium(I) more likely than to thallium(III), making +1 the more likely oxidation state.Sony VAIO VGN-NS11MR/S Battery

A number of standard electrode potentials, depending on the reaction under study, is reported for indium:

Indium is a post-transition metal and chemically, is the intermediate element between its group 13 neighbors gallium andthallium.Sony VAIO VGN-NS11M/S Battery

It shows two main oxidation states, which are +1 and +3, with latter being more stable, where as the only common oxidation state of gallium is +3 and thallium shows +1 more likely than +3, with thallium(III) being a moderately strongoxidizing agent, while indium(III) is stable and indium(I) is a powerful reducing agent.Sony VAIO VGN-NS11SR/S Battery

Indium does not react with water, but it is oxidized by stronger oxidizing agents, such as halogens or oxalic acid, to give indium(III) compounds. It does not react with boron, silicon or carbon, and the corresponding boride, silicide or carbide are not known. Similarly, reaction between indium and hydrogen has not been observed, but both indium(I) and indium(III) hydridesare known.Sony VAIO VGN-NS11S/S Battery

Indium(III) oxide is formed at hot temperatures during reaction between indium and oxygen, with blue flame. It is amphoteric, i. e. it can react with both acids and bases. Its reaction with water results in insoluble indium(III) hydroxide, which is also amphoteric, reacting with alkalies to give indates(III) and with acids to give indium(III) salts:Sony VAIO VGN-NS11ZR/S Battery

In(OH)3 + 2 NaOH ? 2 Na[InO2] + H2O

In(OH)3 + 3 HCl ? InCl3 + 3 H2O

The hydrolysis of sodium indate(III) gives weak indic acid, HInO2. Out of common indium(III) salts, chloride, sulfate and nitrate are soluble.Sony VAIO VGN-NS11Z/S Battery

In water solutions, In3+ and [InO2]- ions are hydrolyzed to give InOH2+ and HInO2 due to generally amphoteric character of indium(III) ions. Indium(III) compounds are not well-soluble, similarly to thallium(III) compounds; however, indium(III) salts of strong acids, such as chloride, sulfate and nitrate are soluble, hydrolyzing in water solutions.Sony VAIO VGN-NS12M/S Battery

The In3+ ion is colorless in solution because of the absence of unpaired electrons in the d- and f-electron shells.

Indium(I) compounds are not as common as indium(III) ones; only chloride, bromide, iodide, sulfide and cyclopentadienyl are well-characterized. Indium(I) sulfide is the product of reaction between indium and sulfur or indium and hydrogen sulfide, and can be received at 700—1000 °C.Sony VAIO VGN-NS12M/W Battery

Indium(I) oxide black powder is received at 850 °C during reaction between indium andcarbon dioxide or during decomposition of indium(III) oxide at 1200 °C. Cyclopentadienylindium(I), which was the first organoindium(I) compound reported,[8] is polymer consisting of zigzag chains of alternating indium atoms and cyclopentadienyl complexes.Sony VAIO VGN-NS12S/S Battery

Less frequently, indium shows intermediate oxidation state +2, which lies between the common ones, most notably in halides, In2X4and [In2X6]2-. Several other compounds are known to combine indium(I) and indium(III), such as InI6(InIIICl6)Cl3,InI5(InIIIBr4)2(InIIIBr6), InIInIIIBr4.Sony VAIO VGN-NS21M/P Battery

Indium occurs naturally on Earth only in two primordial nuclides, indium-113 and indium-115. Out of this two, indium-115 makes up 95.7% of all indium but it is radioactive, decaying to tin-115 via beta decay with half-life of 4.41×1014 years, four orders of magnitude larger than the age of the universe and nearly 50,000 times longer than that of natural thorium.Sony VAIO VGN-NS21M/W Battery

This effect is uncommon among stable chemical elements; only indium, tellurium, and rhenium have been shown that their most abundant isotopes are radioactive. However, the less common natural isotope of indium, indium-113, is stable.

Indium has 39 known isotopes, ranging in mass between 97 and 135.Sony VAIO VGN-NS21S/S Battery

Only one of them is stable and one has half-life exceeding 1014 years; the most stable other indium isotope is indium-111, which has half-life of approximately 2.8 days. All other isotopes have half-lives shorter than 5 hours. Indium also has 47 meta states, out of which indium-114m1 is the most stable, being more stable than ground state of any indium isotope, except for the primordial ones.Sony VAIO VGN-NS21S/W Battery

Creation and occurrence

Indium is created via the long-lasting, (up to thousands of years), s-process in low-medium mass stars (which range in mass between 0.6 and 10 masses of Sun). When a silver-109 atom, which comprises approximately half of all silver in existence, catches a neutron, it undergoes a beta decay to become cadmium-110.Sony VAIO VGN-NS21Z/S Battery

Capturing further neutrons, it becomes cadmium-115, which decays to indium-115 via anotherbeta decay. This explains why the radioactive isotope predominates in abundance compared to the stable one.

Indium is 61st most abundant element in the Earth's crust at approximately 49 ppb, making indium approximately as abundant as mercury.Sony VAIO VGN-NS31M/P Battery

Fewer than 10 indium minerals are known, such as dzhalindite(In(OH)3) and indite (FeIn2S4), but none of these occurs in significant deposits.

Based on content of indium in zinc ore stocks, there is a worldwide reserve base of approximately 6,000 tonnes of economically viable indium.Sony VAIO VGN-NS31M/W Battery

This figure has led to estimates suggesting that, at current consumption rates, there is only 13 years' supply of indium left. However, the Indium Corporation, the largest processor of indium, claims that, on the basis of increasing recovery yields during extraction, recovery from a wider range of base metals (including tin, copper and other polymetallic deposits)Sony VAIO VGN-NS31S/S Battery

and new mining investments, the long-term supply of indium is sustainable, reliable and sufficient to meet increasing future demands.

This conclusion may be reasonable considering that silver, which is one-third as abundant as indium in the Earth's crust,Sony VAIO VGN-NS31Z/P Battery

is currently mined at approximately 18,300 tonnes per year, which is 40 times greater than current indium mining rates.

In 1863, the German chemists Ferdinand Reich and Hieronymous Theodor Richter were testing ores from the mines around Freiberg, Saxony.Sony VAIO VGN-NS31Z/S Battery

They dissolved the mineralspyrite, arsenopyrite, galena and sphalerite in hydrochloric acid and distilled the raw zinc chloride. As it was known that ores from that region sometimes containthallium they searched for the green emission lines with spectroscopic methods. The green lines were absent but a blue line was present in the spectrum.Sony VAIO VGN-NS31Z/W Battery

As no element was known with a bright blue emission they concluded that a new element was present in the minerals. They named the element with the blue spectral line indium, from the indigo color seen in its spectrum. Richter went on to isolate the metal in 1864.At the World Fair 1867 an ingot of 0.5 kg (1.1 lb) was presented.Sony VAIO VGN-NS38M/P Battery

In 1924, indium was found to have a valuable ability to stabilize non-ferrous metals, which was its first significant use for the element.It took until 1936 that the U.S. Bureau of Mines list indium as a commodity, and even in early 1950s only very limited applications for indium were known, the most of which was makinglight-emitting diodes and engines for aircrafts during the World War II.Sony VAIO VGN-NS38M/W Battery

The start of production of indium containing semiconductors started in 1952. The development and widespread use of indium containing nuclear control rods increased the demand during the 1970s, the use of indium tin oxide in liquid crystal displays increased and became the major application by 1992.Sony VAIO VGN-NS130E/L Battery

Production

The lack of indium mineral deposits and the fact that indium is enriched in sulfidic lead, tin, copper, iron and predominately in zinc deposits, makes zinc production the main source for indium. The indium is leached from slag and dust of zinc production. Further purification is done by electrolysis.Sony VAIO VGN-NS130E/S Battery

Indium is produced mainly from residues generated during zinc ore processing but is also found in iron, lead, and copper ores.[2]China is a leading producer of indium. The Teck Cominco refinery in Trail, British Columbia, is a large single source indium producer, with production of 32,500 kg in 2005, 41,800 kg in 2004 and 36,100 kg in 2003.Sony VAIO VGN-NS130E/W Battery

South American Silver Corporation's Malku Khota property in Bolivia is a large resource of indium with an indicated resource of 1,481 tonnes and inferred resource of 935 tonnes. Adex Mining Inc.’s Mount Pleasant Mine in New Brunswick, Canada, holds some of the world’s total known indium resources.Sony VAIO VGN-NS140E/L Battery

The amount of indium consumed is largely a function of worldwide LCD production. Worldwide production is currently 476 tonnes per year from mining and a further 650 tonnes per year from recycling. Demand has risen rapidly in recent years with the popularity of LCD computer monitors and television sets, which now account for 50% of indium consumption.Sony VAIO VGN-NS140E/S Battery

Increased manufacturing efficiency and recycling (especially in Japan) maintain a balance between demand and supply. According to theUNEP, indium's end-of-life recycling rate is less than 1%. Demand increased as the metal is used in LCDs and televisions, and supply decreased when a number ofChinese mining concerns stopped extracting indium from their zinc tailings.Sony VAIO VGN-NS140E/W Battery

In 2002, the price was US$94 per kilogram. The recent changes in demand and supply have resulted in high and fluctuating prices of indium, which from 2006 to 2009 ranged from US$382/kg to US$918/kg.

Applications

The first large-scale application for indium was as a coating for bearings in high-performance aircraft engines during World War II.Sony VAIO VGN-NS190J/L Battery

Afterward, production gradually increased as new uses were found in fusible alloys, solders, and electronics. In the 1950s, tiny beads of it were used for the emitters and collectors of PNP alloy junction transistors. In the middle and late 1980s, the development of indium phosphide semiconductors and indium tin oxide thin films for liquid crystal displays (LCD) aroused much interest.Sony VAIO VGN-NS190J/S Battery

By 1992, the thin-film application had become the largest end use.

Electronics

  • Indium oxide (In2O3) and indium tin oxide (ITO) are used as a transparent conductive coating applied to glass substrates in the making of electroluminescent panels.Sony VAIO VGN-NS190J/W Battery
  • Some indium compounds such as indium antimonide, indium phosphide,[38] and indium nitride[39] are semiconductors with useful properties.
  • Indium is used in the synthesis of the semiconductor copper indium gallium selenide (CIGS), which is used for the manufacture of thin film solar cells.Sony VAIO VGN-NS235J/L Battery
  • Used in light-emitting diodes (LEDs) and laser diodes based on compound semiconductors such as InGaN, InGaP that are fabricated by Metalorganic Vapor Phase Epitaxy (MOVPE) technology.
  • Ultrapure metalorganics of indium include high purity trimethylindium (TMI), which is used as a precursor in III-V compound semiconductors, while it is also used as the semiconductor dopant in II-VI compound semiconductors.Sony VAIO VGN-NS235J/P Battery
  • One of many substitutes for mercury in alkaline batteries to prevent the zinc from corroding and releasing hydrogen gas.[43]
  • Very small amounts used in aluminium alloy sacrificial anodes (for salt water applications) to prevent passivation of the aluminium.Sony VAIO VGN-NS235J/S Battery
  • To bond gold electrical test leads to superconductors, indium is used as a conducting adhesive and applied under a microscope with precision tweezers.
  • In the form of a wire it is used as a vacuum seal and a thermal conductor in cryogenics and ultra-high vacuum applications. For example, in manufacturing gaskets which deform to fill gaps.Sony VAIO VGN-NS235J/W Battery
  • Used as a calibration material for Differential scanning calorimetry.
  • It is an ingredient in the gallium-indium-tin alloy Galinstan, which is liquid at room temperature while not being toxic like mercury.Sony VAIO VGN-NS240E/L Battery
  • Indium tin oxide is used as a light filter in low pressure sodium vapor lamps. The infrared radiation is reflected back into the lamp, which increases the temperature within the tube and therefore improves the performance of the lamp.
  • Indium's melting point of 429.7485 K (156.5985 °C) is a defining fixed point on the international temperature scale ITS-90.Sony VAIO VGN-NS290J/L Battery
  • Indium's high neutron capture cross section for thermal neutrons makes it suitable for use in control rods for nuclear reactors, typically in an alloy containing 80% silver, 15% indium, and 5% cadmium.
  • In nuclear engineering, the (n,n') reactions of 113In and 115In are used to determine magnitudes of neutron fluxes.Sony VAIO VGN-NS290J/S Battery
  • Indium is also used as a thermal interface material by personal computer enthusiasts in the form of pre-shaped foil sheets fitted between the heat-transfer surface of a microprocessor and its heat sink. The application of heat partially melts the foil and allows the indium metal to fill in any microscopic gaps and pits between the two surfaces, removing any insulating air pockets that would otherwise compromise heat transfer efficiency.Sony VAIO VGN-NS50B/L Battery
  • 111In emits gamma radiation and is used in indium leukocyte imaging, or indium scintigraphy, a technique of medical imaging that is particularly helpful in differentiating conditions such as osteomyelitis from decubitus ulcers for assessment of route and duration of antibiotic therapy.Sony VAIO VGN-NS50B/W Battery
  • Indium leukocyte scintigraphy has many applications, including early phase drug development, and the monitoring of activity of white blood cells. For the test, blood is taken from the patient, white cells removed, labeled with the radioactive111In, then re-injected back into the patient.Sony VAIO VGN-NS51B/L Battery
  • Gamma imaging will then reveal any areas of on-going white cell localization such as new and developing areas of infection.

Precautions and health issues

Pure indium in metal form is considered non-toxic by most sources. In the welding and semiconductor industries, where indium exposure is relatively high, there have been no reports of any toxic side-effects.Sony VAIO VGN-NS51B/P Battery

Indium compounds, like aluminum compounds, complex with hydroxyls to form insoluble salts in basic conditions, and are thus not well-absorbed from food, giving them fairly low oral toxicty. Soluble indium(III) is toxic when delivered parenterally, however, causing damage primarily to the kidney (both inner and outer parts), but additionally to heart and liver, and may be teratogenic.Sony VAIO VGN-NS51B/W Battery

Other indium compounds are toxic when administered outside the gastrointestinal tract: for example, anhydrous indium trichloride (InCl3) and indium phosphide (InP) are quite toxic when delivered into the lungs (the latter is a suspected carcinogen).

Tin is a chemical element with the symbol Sn (for Latin: stannum) and atomic number 50.Sony VAIO VGN-NS52JB/L Battery

It is a main group metal ingroup 14 of the periodic table. Tin shows chemical similarity to both neighboring group 14 elements, germanium and lead and has two possible oxidation states, +2 and the slightly more stable +4. Tin is the 49th most abundant element and has, with 10 stable isotopes, the largest number of stable isotopes in the periodic table.Sony VAIO VGN-NS52JB/P Battery

Tin is obtained chiefly from the mineralcassiterite, where it occurs as tin dioxide, SnO2.

This silvery, malleable poor metal is not easily oxidized in air and is used to coat other metals to prevent corrosion. The first alloy, used in large scale since 3000 BC, was bronze, an alloy of tin and copper.Sony VAIO VGN-NS52JB/W Battery

After 600 BC pure metallic tin was produced. Pewter, which is an alloy of 85–90% tin with the remainder commonly consisting of copper, antimony and lead, was used for flatware from the Bronze Age until the 20th century. In modern times tin is used in many alloys, most notably tin/lead soft solders, typically containing 60% or more of tin.Sony VAIO VGN-NS70B/W Battery

Another large application for tin is corrosion-resistant tin plating of steel. Because of its low toxicity, tin-plated metal is also used for food packaging, giving the name to tin cans, which are made mostly of steel.

Physical properties

Tin is a malleable, ductile and highly crystalline silvery-white metal. When a bar of tin is bent, a crackling sound known as the tin cry can be heard due to the twinning of the crystals.Sony VAIO VGN-NS71B/W Battery

Tin melts at a low temperature of about 232 °C, which is further reduced to 177.3 °C for 11-nm particles.

?-tin (the metallic form, or white tin), which is stable at and above room temperature, is malleable. In contrast, ?-tin (nonmetallic form, or gray tin), which is stable below 13.2 °C, isbrittle. ?-tin has a diamond cubic crystal structure, similar to diamond, silicon or germanium.Sony VAIO VGN-NS72JB/W Battery

?-tin has no metallic properties at all because its atoms form a covalent structure where electrons cannot move freely. It is a dull-gray powdery material with no common uses, other than a few specialized semiconductor applications.  These two allotropes, ?-tin and ?-tin, are more commonly known as gray tin and white tin, respectively.Sony VAIO VGN-NS90HS Battery

Two more allotropes, ? and ?, exist at temperatures above 161 °C and pressures above several GPa. Although the ?-? transformation temperature is nominally 13.2 °C, impurities (e.g. Al, Zn, etc.) lower the transition temperature well below 0 °C, and upon addition of Sb or Bi the transformation may not occur at all, increasing the durability of the tin.Sony VAIO VGN-NS92JS Battery

Commercial grades of tin (99.8%) resist transformation because of the inhibiting effect of the small amounts of bismuth, antimony, lead and silver present as impurities. Alloying elements such as copper, antimony, bismuth, cadmium and silver increase its hardness. Sony VAIO VGN-NS92XS Battery

92XS laptop battery">Tin tends rather easily to form hard, brittle intermetallic phases, which are often undesirable. It does not form wide solid solution ranges in other metals in general, and there are few elements that have appreciable solid solubility in tin. Simple eutectic systems, however, occur with bismuth, gallium, lead, thallium and zinc.Sony VAIO VGN-NW11S/S Battery

Tin becomes a superconductor below 3.72 K.[7] In fact, tin was one of the first superconductors to be studied; the Meissner effect, one of the characteristic features of superconductors, was first discovered in superconducting tin crystals.

Chemical properties

Tin resists corrosion from water but can be attacked by acids and alkalis. Tin can be highly polished and is used as a protective coat for other metals.Sony VAIO VGN-NW11S/T Battery

In this case the formation of a protective oxide layer is used to prevent further oxidation. This oxide layer forms on pewter and other tin alloys.[9] Tin acts as a catalyst when oxygen is in solution and helps accelerate chemical attack.

Tin is the element with the greatest number of stable isotopes, ten;Sony VAIO VGN-NW11Z/S Battery

these include all those with atomic masses between 112 and 124, with the exception of 113, 121 and 123. Of these, the most abundant ones are 120Sn (at almost a third of all tin),118Sn, and 116Sn, while the least abundant one is 115Sn. The isotopes possessing even atomic numbers have no nuclear spinwhile the odd ones have a spin of +1/2.Sony VAIO VGN-NW11Z/T Battery

Tin, with its three common isotopes 115Sn, 117Sn and 119Sn, is among the easiest elements to detect and analyze by NMR spectroscopy, and its chemical shifts are referenced against SnMe4 .

This large number of stable isotopes is thought to be a direct result of tin possessing an atomic number of 50, which is a "magic number" in nuclear physics.Sony VAIO VGN-NW21EF/S Battery

There are 28 additional unstable isotopes that are known, encompassing all the remaining ones with atomic masses between 99 and 137. Aside from 126Sn, which has a half-life of 230,000 years, all the radioactive isotopes have a half-life of less than a year.Sony VAIO VGN-NW21JF Battery

The radioactive 100Sn is one of the few nuclides possessing a "doubly magic" nucleus and was discovered relatively recently, in 1994. Another 30 metastable isomers have been characterized for isotopes between 111 and 131, the most stable of which being 121mSn, with a half-life of 43.9 years.Sony VAIO VGN-NW21MF Battery

Etymology

The English word 'tin' is Germanic; related words are found in the other Germanic languages—German zinn, Swedishtenn, Dutchtin, etc.—but not in other branches of Indo-European except by borrowing (e.g. Irish tinne). Its origin is unknown.Sony VAIO VGN-NW21MF/W Battery

The Latin name stannum originally meant an alloy of silver and lead, and came to mean 'tin' in the 4th century BCE[13]—the earlier Latin word for it was plumbum candidum 'white lead'. Stannum apparently came from an earlier st?gnum (meaning the same thing),[12] the origin of the Romance and Celtic terms for 'tin'.Sony VAIO VGN-NW21ZF Battery

The origin of stannum/st?gnum is unknown; it may be pre-Indo-European. The Meyers Konversationslexikon speculates on the contrary that stannum is derived from Cornishstean, and is proof that Cornwall in the first centuries AD was the main source of tin.Sony VAIO VGN-NW31EF/W Battery

Antiquity

Tin extraction and use can be dated to the beginnings of the Bronze Age around 3000 BC, when it was observed that copper objects formed of polymetallic ores with different metal contents had different physical properties.Sony VAIO VGN-NW31JF Battery

The earliest bronze objects had tin or arsenic content of less than 2% and are therefore believed to be the result of unintentional alloying due to trace metal content in the copper ore It was soon discovered that the addition of tin or arsenic to copper increased its hardness and made casting much easier,Sony VAIO VGN-NW320F/B Battery

which revolutionized metal working techniques and brought humanity from the Copper Age or Chalcolithic to the Bronze Age around 3000 BC. Early tin exploitation appears to have been centered on placer deposits of cassiterite.

The first evidence of tin use for making bronze appears in the Near East and the Balkans around 3000 BC.Sony VAIO VGN-NW320F/TC Battery

It is still unclear where the earliest tin was mined, as tin deposits are very rare and evidence of early mining is scarce. Europe's earliest mining district appears to be located in Erzgebirge, on the border between Germany and Czech Republic and is dated to 2500 BC. From there tin was traded north to the Baltic Sea and south to the Mediterranean following the Amber Road trading route.Sony VAIO VGN-NW35E Battery

Tin mining knowledge spread to other European tin mining districts from Erzgebirge and evidence of tin mining begins to appear in Brittany, Devon and Cornwall, and in the Iberian Peninsula around 2000 BC. These deposits saw greater exploitation when they fell under Roman control between the third century BC and the first century AD.Sony VAIO VGN-NW380F/S Battery

Demand for tin created a large and thriving network amongst Mediterranean cultures of Classical times.[20][21] By the Medieval period, Iberia's and Germany's deposits lost importance and were largely forgotten while Devon and Cornwall began dominating the European tin market.Sony VAIO VGN-NW380F/T Battery

In the Far East, the tin belt stretching from Yunnan province in China to the Malaysian Peninsulabegan being exploited sometime between the third and second millennium BC. The deposits in Yunnan province were not mined until around 700 BC, but by the Han Dynasty had become the main source of tin in China according to historical texts of the Han, Jin, Tang, and Song dynasties.Sony VAIO VGN-NW50JB Battery

Other regions of the world developed tin mining industries at a much later date. In Africa, theBantu culture extracted, smelted and exported tin between the 11th and 15th centuries AD,  in the Americas tin exploitation began around 1000 AD, and in Australia it began with the arrival of Europeans in the 17th century.Sony VAIO VGN-NW51FB/N Battery

Modern times

During the Middle Ages, and again in the early 19th century, Cornwall was the major tin producer. This changed after large amounts of tin were found in the Bolivian tin belt and the east Asian tin belt, stretching from China through Thailand and Laos to Malaya and Indonesia.Sony VAIO VGN-NW51FB/W Battery

Tasmania also hosts deposits of historical importance, most notably Mount Bischoff and Renison Bell.

In 1931 the tin producers founded the International Tin Committee, followed in 1956 by the International Tin Council, an institution to control the tin market. After the collapse of the market in October 1985 the price for tin nearly halved.Sony VAIO VGN-NW70JB Battery

Tin foil was once a common wrapping material for foods and drugs; replaced in the early 20th century by the use of aluminium foil, which is now commonly referred to as tin foil. Hence one use of the slang term "tinnie" or "tinny" for a small pipe for use of a drug such as cannabis or for a can of beer.Sony VAIO VGN-NW71FB/N Battery

Today, the word "tin" is often improperly used as a generic term for any silvery metal that comes in sheets. Most everyday materials that are commonly called "tin", such as aluminium foil,beverage cans, corrugated building sheathing and tin cans, are actually made of steel or aluminium, although tin cans (tinned cans) do contain a thin coating of tin to inhibit rust.Sony VAIO VGN-NW71FB/W Battery

Likewise, so-called "tin toys" are usually made of steel, and may have a coating of tin to inhibit rust. The original Ford Model T was known colloquially as the "Tin Lizzy".

 

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