Tin is a chemical element with symbol Sn (for Latin: stannum) and atomic number 50. Tin is obtained chiefly from the mineral cassiterite, where it occurs as tin dioxide, SnO2. 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. 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. This silvery, malleable poor metal is not easily oxidized in air and is used to coat other metals to prevent corrosion
Tin becomes a superconductor below 3.72 K. 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. 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. Tin melts at a low temperature of about 232 °C (449.6 °F), which is further reduced to 177.3 °C (351 °F) for 11-nm particles.
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