サマリウム 化学特性,用途語,生産方法
解説
Sm．原子番号62の元素．電子配置[Xe]4f 66s2の周期表3族ランタノイド元素．希土類元素セリウム族の一つ．原子量150.36(2)．質量数144(3.07(7)％)，147(14.99(18)％)，148(11.24(10)％)，149(13.82(7)％)，150(7.38(1)％)，152(26.75(16)％)，154(22.75(29)％)の7種の天然に存在する同位体と，質量数128の放射性同位体が知られている．天然に存在する同位体のうち，146Sm，147Sm，148Sm はそれぞれ，半減期1.03×108 y，1.06×1011 y，7×1015 y のα放射体である．
森北出版「化学辞典（第2版）
特性
単体は黄灰色の金属，融点 1072℃，比重 7.536。ごく弱い天然放射能をもつ。熱水と作用して水素を発生し，無機酸に溶ける。3価の陽イオンのほか2価もつくる。
用途
耐熱性永久磁石，サマリウム-コバルト磁石(SmCo5，Sm2Co17，Sm2(Co,Fe,Cu,Zr))用が最大の用途である．
1980年代にはウォークマンなどヘッドフォンに多用されたが，より安価で強力なNd-Fe-B磁石にとってかわられた．携帯電話用にはまだ使われることもある．
化学的特性
silvery grey powder
物理的性質
Samarium is a hard, brittle, silver-white metal. When freshly cut, it does not tarnish significantlyunder normal room temperature conditions. Four of its isotopes are radioactive andemit alpha particles (helium nuclei). They are Sm-146, Sm-147, Sm-148, and Sm-149.
Its melting point is 1,074°C, its boiling point is 1,794°C, and its density is 7.52g.cm
3.
同位体
There are 41 known isotopes of samarium. Seven of these are consideredstable. Sm-144 makes up just 3.07% of the natural occurring samarium, Sm-150 makesup 7.38% of natural samarium found on Earth, Sm-152 constitutes 26.75%, and Sm-154 accounts for 22.75%. All the remaining isotopes are radioactive and have very longhalf-lives; therefore, they are considered “stable.” All three contribute to the natural occurrenceof samarium: Sm-147 = 14.99%, Sm-148 = 11.24%, and Sm-149 = 13.82%.
Samarium is one of the few elements with several stable isotopes that occur naturallyon Earth.
名前の由来
It is named after the mineral samarskite.
天然物の起源
Samarium is the 39th most abundant element in the Earth’s crust and the fifth in abundance(6.5 ppm) of all the rare-earths. In 1879 samarium was first identified in the mineralsamarskite [(Y, Ce U, Fe)
3 (Nb, Ta, Ti
5)O
16]. Today, it is mostly produced by the ion-exchangeprocess from monazite sand. Monazite sand contains almost all the rare-earths, 2.8% of whichis samarium. It is also found in the minerals gadolinite, cerite, and samarskite in South Africa,South America, Australia, and the southeastern United States. It can be recovered as a byproductof the fission process in nuclear reactors.
特性
Samarium is somewhat resistant to oxidation in air but will form a yellow oxide over time. Itignites at the rather low temperature of 150°C. It is an excellent reducing agent, releases hydrogenwhen immersed in water, and has the capacity to absorb neutrons in nuclear reactors.
使用
Samarium is easy to magnetize, but very difficult to demagnetize. This makes it ideal forthe manufacture of permanent magnets (SmCo
5) that are part of the hard disks for computers.Samarium is also used as a neutron absorber in nuclear reactors, as well as for lasers andmetallurgical research. It makes up about 1% of the metals in misch metal, an alloy in cigarettelighter flints. It is also one of several rare-earths used in floodlights and carbon-arc lights usedby the motion picture industry. Samarium is used as a catalyst in several industries, includingthe dehydrogenation of ethanol alcohol.
定義
A silvery element
of the lanthanoid series of metals. It
occurs in association with other lanthanoids.
Samarium is used in the metallurgical,
glass, and nuclear industries.
Symbol: Sm; m.p. 1077°C; b.p.
1791°C; r.d. 7.52 (20°C); p.n. 62; r.a.m.
150.36.
危険性
The salts of samarium are toxic if ingested. These salts react with water, liberating hydrogen,which may explode.
サマリウム 上流と下流の製品情報
原材料
準備製品