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[haf-nee-uh m, hahf-] /ˈhæf ni əm, ˈhɑf-/
noun, Chemistry
a gray, toxic metallic element with a high melting point (over 2000°C), found in most zirconium minerals. Symbol: Hf; atomic weight: 178.49; atomic number: 72; specific gravity: 12.1.
1923; < New Latin Hafn(ia) Copenhagen + -ium Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for hafnium
  • hafnium is used in nuclear control rods because of its high thermal neutron absorption cross section.
  • The job of such a precursor compound is to deliver a metal atom, such as hafnium, to the surface of a hot silicon wafer.
  • In the top photo, the small size of the hafnium beads is illustrated next to a penny.
British Dictionary definitions for hafnium


a bright metallic element found in zirconium ores: used in tungsten filaments and as a neutron absorber in nuclear reactors. Symbol: Hf; atomic no: 72; atomic wt: 178.49; valency: 4; relative density: 13.31; melting pt: 2231±20°C; boiling pt: 4603°C
Word Origin
C20: New Latin, named after Hafnia, Latin name of Copenhagen + -ium
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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Word Origin and History for hafnium

rare element, 1923, Modern Latin, from Hafnia, Medieval Latin form of Danish Havn "harbor," the usual pre-1400 name of Copenhagen, Denmark, where it was discovered by physicist Dirk Coster (1889-1950) and chemist George de Hevesy (1885-1966).

Online Etymology Dictionary, © 2010 Douglas Harper
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hafnium in Medicine

hafnium haf·ni·um (hāf'nē-əm)
Symbol Hf
A metallic element found with zirconium and used in nuclear reactor control rods and in tungsten alloys used in filaments. Atomic number 72; atomic weight 178.49; melting point 2,230°C; boiling point 4,600°C; specific gravity 13.3; valence 4.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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hafnium in Science
Symbol Hf
A bright, silvery metallic element that occurs in zirconium ores. Because hafnium absorbs neutrons better than any other metal and is resistant to corrosion, it is used to control nuclear reactions. Atomic number 72; atomic weight 178.49; melting point 2,220°C; boiling point 5,400°C; specific gravity 13.3; valence 4. See Periodic Table.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Encyclopedia Article for hafnium


chemical element (atomic number 72), metal of Group IVb of the periodic table. It is a ductile metal with a brilliant silvery lustre. The Dutch physicist Dirk Coster and the Hungarian-Swedish chemist George Charles de Hevesy discovered (1923) hafnium in Norwegian and Greenland zircons by analyzing their X-ray spectra. They named the new element for Copenhagen (in New Latin, Hafnia), the city in which it was discovered. Hafnium is dispersed in the Earth's crust to the extent of three parts per million and is invariably found in zirconium minerals up to a few percent compared with zirconium. Altered zircons, like some alvites and cyrtolites, products of residual crystallization, show greater percentages of hafnium (up to 17 percent hafnium oxide in cyrtolite from Rockport, Mass., U.S.). Commercial sources of hafnium-bearing zirconium minerals are found in beach sands and river gravel in the United States (principally Florida), Australia, Brazil, western Africa, and India. Hafnium vapour has been identified in the Sun's atmosphere.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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