Characteristic function of indium

1863, German scholars F. Reich and H. Richter discovered indium when analyzing sphalerite by spectrometry, but they never dreamed that it would have such a broad application prospect. 1924, the world only produced 1 kg indium. By 1980, the global indium output reached 45.5 tons, 1990 reached 133 tons and 1999 reached 235 tons. At present, the global output is only about 300 tons. The price of indium was only a few tens of dollars/kg at first, and it reached 645 dollars/kg in 1980 because of the wide application of atomic energy control facilities. Since then, the price has never recovered. On May 8th, the average price was 100- 130 USD/kg, and in 2003, the average price was 10-3 USD/kg. Especially when the IT bubble burst from 200 1 year 10 to September 2002, the price was as low as 55-66 USD/kg. Then slowly rise. At the beginning of May 2003, the price of indium reached 1.25- 1.70 USD/kg. June 2003: 140- 170 USD/kg; In 2004, it rose sharply, from $300/kg at the beginning of the year to $800/kg at the end of the year, nearly tripling. In March 2005, it has reached 10 10- 1070 USD/kg. After that, the price slowly adjusted at a high level, ranging from 800-870 USD/kg. In March 2006, 16 was 930/990 USD/kg, and in April 2006, 1000/ 1060 USD/kg. It is optimistically estimated that the indium price will reach 1400 USD/kg. Why is indium sought after by people? This should start with her life experience. Indium is the third group element in the periodic table of elements and the fourth group element in the series of boron, aluminum, gallium, indium and thallium. The atomic number is 49 and the atomic weight is 1 14.82. Indium is a dispersed element, and its content in the crust is very low, and its abundance is similar to that of silver, which is 0.05× 10-6. At present, only 8 kinds of indium independent minerals have been found, which is extremely rare. Most indium exists as impurities in other minerals, generally distributed in lead-zinc mines and tin mines. Extracting indium is very difficult. At present, only lead-zinc smelters and tin smelters recover indium by-products. Most indium is recovered from leaching residue of zinc hydrometallurgy. After chemical treatment, indium can be obtained by solvent extraction. Indium can also be obtained by reducing slag leaching solution with zinc sheet. Indium with purity of 99.97% can be obtained after further electrolytic refining. High purity indium with purity of 99.9999% still needs electrolytic purification. Therefore, at present, the global indium production is only about 300 tons, and the production capacity will not increase significantly. It is estimated that the proven reserves of indium resources in the world are about 6.5438+0.3 million tons. "Rare things are precious", and the price of indium remains high. But this is only one aspect of the problem, and more importantly, its unique physical and chemical properties turn this ugly duckling into a beautiful white swan. First: Indium metal is silvery white with a slight blue color, with bright luster, which makes a sound when it bends. It is alloyed with copper, silver and gold to make dentures. Secondly, indium has a low melting point (156.6 1℃), a high boiling point (2080℃), good conductivity and ductility, and is softer than lead, so it can be scored with nails. Strong plasticity, can be pressed into extremely thin metal sheet. Its oxide can form a transparent conductive film, which has been widely used in indium tin oxide (ITO), semiconductors, low melting point alloys and so on in recent years. In particular, indium tin oxide (ITO) is widely used as a transparent conductive film because of its visible light transmittance above 95%, ultraviolet absorption rate ≥70%, microwave attenuation rate ≥85%, good conductivity and processability, and wear resistance and chemical corrosion resistance of the film. With the rapid development of IT industry, ITO target (containing about 70% indium) is used as transparent electrode coating in various new LCD displays such as notebook computers, televisions and mobile phones, as well as touch screens and architectural glass. The demand for indium has increased by more than 30% every year. The rapid growth of flat panel displays in the world market has become the most important end user of indium production in the world, including the rapid development and application of major flat panel displays such as flat panel TVs, desktop computer monitors, notebook computers with Internet access, and mobile phones. The demand for indium in the international market has increased sharply, and no new materials have been developed to replace ITO. Thirdly, from room temperature to melting point, indium reacts slowly with oxygen in the air, forming an extremely thin oxide film on the surface. At higher temperature, indium reacts with oxygen, halogen, sulfur, selenium, tellurium and phosphorus. Indium oxidizes slowly in air; Bulk indium does not react with boiling water and alkali, while powdered indium can react with water to produce indium hydroxide. Indium reacts slowly with cold dilute acid and is easily soluble in concentrated hot inorganic acid, acetic acid and oxalic acid. Indium can be used as coating or alloy with other metals to enhance the corrosion resistance of engine bearings; Indium has excellent reflectivity and can be used to make mirrors. Silver-lead-indium alloy can be used as bearing material for high-speed aero-engines. Every addition of 65438 0% indium in fusible wood alloy can reduce the melting point by 65438 0.45℃. Indium compound semiconductors include indium antimonide (communication laser light source, solar cell), indium phosphide, indium antimonide (infrared detection, magneto-optical device, solar converter, etc. ). Fourthly, indium alloy can be used as reactor control rod, which can sensitively detect neutron radiation; Can be used in the landing cabin, and will not be brittle or broken when landing.