词条 | samarium |
释义 | samarium chemical element ![]() Because of its high absorption cross section for thermal neutrons, samarium has been suggested for application in nuclear reactor control rods and for neutron shielding. Other uses are in special luminescent and infrared-absorbing glasses, in inorganic and organic catalysis, in magnetic alloys (combined with cobalt), and in the electronics and ceramics industries. Samarium is a minor constituent of misch metal (a mixture of cerium and other rare-earth metals, used in ferrous and nonferrous alloys). The seven naturally occurring isotopes of samarium are samarium-144 (3.1 percent), samarium-147 (15.0 percent), samarium-148 (11.3 percent), samarium-149 (13.8 percent), samarium-150 (7.4 percent), samarium-152 (26.7 percent), and samarium-154 (22.7 percent). Samarium-144, samarium-150, samarium-152, and samarium-154 are stable, but the other three naturally occurring isotopes are alpha emitters. In addition to its more stable +3 oxidation state, samarium, unlike most of the rare earths, has a +2 oxidation state. The Sm2+ ion is a powerful reducing agent that rapidly reacts with oxygen, water, or hydrogen ions. It can be stabilized by precipitation as the extremely insoluble sulfate SmSO4. Other salts of samarium in the +2 state are SmCO3, SmCl2, SmBr2, and Sm(OH)2; they are reddish brown in colour. In its +3 oxidation state samarium behaves as a typical rare-earth element; it forms a series of yellow salts in solutions. atomic number 62 atomic weight 150.36 melting point 1,074° C boiling point 1,794° C density 7.520 g/cm3 (25° C) oxidation states +2, +3 electronic config. 【Xe】4f 65d06s2 |
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