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hafnium 音标拼音: [h'æfniəm] n. 铪 铪 hafnium n 1: a grey tetravalent metallic element that resembles zirconium chemically and is found in zirconium minerals; used in filaments for its ready emission of electrons [synonym: {hafnium}, {Hf}, {atomic number 72}] hafnium \haf"ni*um\ (h[a^]f"n[=e]*[u^]m or h[aum]f"n[=e]*[u^]m), n. A metallic element of atomic number 72 present together with zirconium to the extent of 1% to 5% in zirconium minerals. It is a poisonous, ductile metal with a brilliant silver luster, has an atomic weight of 178.49, and has a high melting point (2227[deg] C). It is used in nuclear reactors, and incandescent lamps as a scavenger of oxygen and nitrogen. See also {norium}. [1913 Webster] hafnium Symbol: Hf Atomic number: 72 Atomic weight: 178.49 Silvery lustrous metallic transition element. Used in tungsten alloys in filaments and electrodes, also acts as a neutron absorber. First reported by Urbain in 1911, existence was finally established in 1923 by D. Coster, G.C. de Hevesy in 1923.
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