The chemical element zirconium has the atomic number 40 and the symbol Zr. The most important source of zirconium is the zircon mineral, from which the term zirconium is derived. The name is related to the Persian word zargun, which means "like gold" or "like gold" in zircon. It is a strong, shiny transition metal similar to titanium and to a lesser extent hafnium. It is gray-white in color. While zirconium is mostly used as a refractory and opacifier, it is also used in small amounts as an alloying agent due to its excellent corrosion resistance. Numerous inorganic and organometallic compounds are formed from zirconium, including zirconium dioxide and zirconocene dichloride. Of the five isotopes that exist in nature, four are stable. Compounds made with zirconium have no known biological purpose.
Properties of Zirconium
Zirconium is a shiny, grayish-white, soft, malleable, ductile metal that is solid at normal temperature; but at lower purities it is brittle and hard. Zirconium is highly flammable in powder form, but is much less likely to ignite when solid. Zirconium has a high level of corrosion resistance to salt water, acids, alkalis and other chemicals. But when fluorine is present, it will dissolve in sulfuric and hydrochloric acids. Zinc alloys become magnetic at temperatures below 35 K.
Zirconium has a melting point of 1855 °C and a boiling point of 4409 °C. On the Pauling scale, zirconium has an electronegativity of 1.33. Zirconium has the fifth lowest electronegativity among the d-block elements with known values, after hafnium, yttrium, lanthanum, and actinium.
Zirconium has a hexagonally close-packed crystal structure called α-Zr at ambient temperature and transforms from α-Zr to β-Zr, a body-centered cubic crystal structure, at 863 °C. Before melting, zirconium is in β-phase.
Isotopes of Zirconium
There are five isotopes of zirconium found in nature. The radioactive elements 90Zr, 91Zr, 92Zr, and 94Zr are all stable, whereas 94Zr is 1,10×1017 It is predicted to undergo double beta decay with a half-life of more than 2,4 year (not seen experimentally). The longest-lived radioisotope of zirconium, 10×XNUMX19 96Zr, which has a half-life of one year. The most common of these naturally occurring isotopes is 51,45Zr, which makes up 90% of all zirconium. Constituting only 2,80% of zirconium, 96Zr is the least common zirconium.
78 synthetic isotopes of zirconium have been created, with atomic masses ranging from 110 to 28. Half-life 1,53×106 93Zr is the longest-lived man-made isotope. The highest mass radioactive isotope of zirconium, 110Zr, is thought to have a half-life of 30 milliseconds. Radioactive isotopes with a mass of 93 or more decay through electron emission, while those with a mass of 89 or less decay through positron emission. An exception is 88Zr, which decays only by electron capture.
There are also five metastable isomers of zirconium: 83mZr, 85mZr, 89mZr, 90m1Zr, 90m2Zr and 91mZr. Of these, the 131m90Zr half-life of 2 nanoseconds is the shortest. The longest-lived element is 4.161mZr, which has a half-life of 89 minutes.
Availability of Zirconium
Earth's crust contains 130 mg/kg of zirconium and seawater contains 0,026 g/L. Due to its inherent instability with water, it is not a natural metal in nature. Zircon (ZrSiO4), a silicate mineral found mainly in Australia, Brazil, India, Russia, South Africa, and the United States, and in lesser concentrations worldwide, is the main commercial source of zirconium. As of 2013, South Africa and Australia carry out two-thirds of the world's zircon mining. Worldwide zircon deposits exceed 60 million tons and 900.000 tons of zirconium are produced annually.
It contains more than 140 different minerals zirconium, including the important ores baddeleyite and eudialyte.
Zirconium has been found in the sun and meteorites and is relatively common in S-type stars. Compared to terrestrial rocks, samples of Moon rock returning from multiple Apollo missions to the Moon had a high level of zirconium oxide.
EPR spectroscopy has been used to investigate the unique 3+ valence state of zirconium. By forming isotopically enriched (94,6%) 91Zr-doped ScPO4 single crystals, the Zr4+ EPR spectrum, which was initially detected as a parasitic signal in Fe-doped ScPO3 single crystals, was definitively recognized. In addition, LuPO4 and YPO4 single crystals, which are naturally abundant and doped with isotopically enriched Zr, were produced and studied.
Source: Wikipedia
Günceleme: 24/04/2023 15:26