 Discovery Information
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| Who: Dirk Coster, George Hevesy |
| When: 1923 |
| Where: Denmark |
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| Name Origin
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| From Hafnia, the Latin name of Copenhagen. |
| "Hafnium" in different languages. |
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| Sources
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| Hafnium does not exist in nature in elemental form. Obtained from the minerals alvite ([(Hf, Th, Zr)SiO4.H2O]), thortveitite ((Sc,Y)2Si2O7) and zircon (ZrSiO4 which usually contain between 1 and 5% hafnium.
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| Abundance
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| Universe: 0.0007 ppm (by weight) |
| Sun: 0.001 ppm (by weight) |
| Carbonaceous meteorite: 0.17 ppm |
| Earth's Crust: 5.3 ppm |
| Seawater: 7 x 10-6 ppm
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| Uses
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| Used in gas-filled and incandescent lamps, reactor control rods because of its ability to absorb neutrons also as a gas scavenger
in vacuum tubes. Used as the electrode in plasma cutting because of its ability to shed electrons into air.
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| It is also used in iron, titanium, niobium, tantalum and other metal alloys.
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| History
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| The existence of a gap in the periodic table for an as-yet undiscovered element 72 was predicted by Henry Moseley in 1914. Hafnium (Latin Hafnia for "Copenhagen", the
home town of Niels Bohr) was discovered by Dirk Coster and Georg von Hevesy in 1923 in Copenhagen, Denmark, validating the original 1869 prediction of Mendeleev. Soon after, the new element was predicted to be associated with zirconium by using the Bohr theory and was finally found in zircon through X-ray spectroscope analysis in Norway.
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| It was separated from zirconium through repeated recrystallization of double ammonium or potassium fluorides by Jantzen and von Hevesy. Metallic hafnium was first prepared by Anton Eduard van Arkel and Jan Hendrik de Boer by passing hafnium tetraiodide vapour
over a heated tungsten filament. This process for differential purification of Zr and Hf is still in use today.
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| Notes
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| A man made radioactive element and the first transactinide element. |
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| Hazards
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| Care needs to be taken when machining hafnium because when it is divided into fine particles, it is pyrophoric and can ignite spontaneously in air.
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