イッテルビウム

外観

銀白色の塊

溶解性

酸に溶け、水にほとんど溶けない。

解説

イッテルビウム，原子番号70の元素．電子配置[Xe]4f 146s2の周期表3族ランタノイド元素．希土類元素イットリウム族の一つ．原子量173.04(3)．質量数168(0.13(1)％)，170(3.04(15)％)，171(14.28(57)％)，172(21.83(67)％)，173(16.13(27)％)，174(31.83(92)％)，176(12.76(41)％)の7種の安定同位体と，質量数148～181の放射性同位体が知られている．

森北出版「化学辞典（第2版）

性質

イッテルビウム，密度6.965 g cm－3(立方最密)，6.54 g cm－3(体心立方)．融点824 ℃，沸点1193 ℃．標準電極電位 Yb3＋/Yb－2.22 V．第一イオン化エネルギー6.254 eV．塩基性は希土類中でも弱い．酸化数2，3．普通，三価で化合物をつくるが，電解により Yb2＋ も得られる．空気中では Yb2＋ は Yb3＋ に酸化される．二価の化合物は，イオン半径が Sr2＋ と似ているため，硫酸塩の溶解度が小さい．化合物は反磁性である．三価の化合物は，ほかの希土類元素と同様の性質を示す．Yb3＋ は無色で常磁性である．光学レンズ用添加剤としての利用のほか，非破壊検査用のγ線源に169Ybが使われている．

発見

希土類の分離は困難なため，この元素の発見は，1843年にC.G. Mosanderがガドリン石(旧名Ytterbite)から酸化物テルビアとして見いだした後，次々に新しい元素の酸化物に分割が進み，最終的に1907年にC.F.Auer von Welsbach(ウェルスバッハ)とG. Urbain(ユルバン)が独立に純粋な元素の分離に成功するまでの長年月を要した．その間にイッテルビウムが元素名として使われていたので，混乱を防ぐためにネオイッテルビウムとされたが，1925年にIUPACがイッテルビウムと決定した．

用途

光学レンズ用添加剤としての利用のほか，非破壊検査用のγ線源に169Ybが使われている．

製造

地殻中の存在度2.2 ppm．ガドリン石，ゼノタイムなどの鉱物中に存在し，純金属はYbCl3-NaCl混合融解塩の黒鉛槽中での電解で得られるイッテルビウム．

化学的特性

metal chips

物理的性質

Ytterbium is a silvery, soft, malleable, and ductile metal with a lustrous metallic shine.It is slightly reactive in air or water at room temperatures. Ytterbium is located next to lastof the rare-earths in the lanthanide series. It slowly oxidizes as it reacts with oxygen in theatmosphere, forming a somewhat duller coating. Ytterbium was the first rare-earth to bediscovered by Carl Gustof Mosander in 1843. More of it exists in the Earth’s crust than oncewas believed.

It was often confused with other rare-earths and was known by two other names, aldebaraniumand cassiopeium. Ytterbium’s melting point is 819°C, its boiling point is 1,196°C, andits density is 6.9654g/cm³.

同位体

There are a total of 37 isotopes of ytterbium. Seven of these are stable, andthey make up all of the natural ytterbium found on Earth. One of these isotopes (Yb-176) has such a long half-life (1.6×10⁺¹⁷years) that it contributes 12.76% of the naturalytterbium existing on Earth, and thus it is considered stable. All the other 30 isotopes areartificially radioactive and produced by nuclear fission in nuclear reactors with half-livesranging from a fraction of a second to 32 days.

名前の由来

Ytterbium is named for the Ytterby quarry located in Sweden.

天然物の起源

Ytterbium is the 45th most abundant element, and it ranks 10th in abundance (2.7 ppm)among the 17 rare-earths found in the Earth’s crust.
It is found in ores along with other rare-earths that were first found in the Ytterby quarryof Sweden. These ores are xenotime, euxenite, gadolinite, and monazite. Monazite river sand is the main source of ytterbium, which is found in India and Brazil and the beaches of Florida.Ytterbium is also found as a decay product of the fission reaction in nuclear reactors.

特性

In the past there was some confusion about the rare-earths because they are not really earthsat all, but rather binary compounds of oxides of metals. Compounding the confusion was thefact that they were always found combined with several other rare-earths.
The salts of ytterbium are paramagnetic, which exhibit weaker magnetic fields than do ironmagnets.

使用

Ytterbium is being applied to numerous fiber amplifier and fiber optic technologies and in various lasing applications.
Ytterbium metal increases its electrical resistance when subjected to very high stresses. This property is used in stress gauges for monitoring ground deformations from earthquakes and nuclear explosions.
Ytterbium can also be used as a dopant to help improve the grain refinement, strength, and other mechanical properties of stainless steel. Some Ytterbium alloys have rarely been used in dentistry.
It is also used as in thermal barrier system bond coatings on nickel, iron and other transitional metal alloy substrates.
Ytterbium Metal, is being applied in improving the grain refinement, strength, and other mechanical properties of stainless steel and alloys. The 169Yb has been used as a radiation source in portable X-ray machines.169Yb is also used in nuclear medicine. Ytterbium can also be used as a dopant to help improve the grain refinement, strength, and other mechanical properties of stainless steel. Some ytterbium alloys have rarely been used in dentistry.
Ytterbium Metal can be further processed to various shapes of ingots, pieces, wires, foils, slabs, rods, discs and powder.

定義

A soft malleable silvery element having two allotropes and belonging to the lanthanoid series of metals. It occurs in association with other lanthanoids. Ytterbium has been used to improve the mechanical properties of steel. Symbol: Yb; m.p. 824°C; b.p. 1193°C; r.d. 6.965 (20°C); p.n. 70; r.a.m. 173.04.

危険性

Ytterbium dust and powder can explode and may be toxic if inhaled. The compound.ytterbium arsenate is a poison.

安全性プロファイル

As a lanthanon it maj7 have an anticoagulant action on blood. Questionable carcinogen with experimental tumorigenic data. Flammable in the form of dust when reacted with air, halogens. See also LANTHANUM and RARE EARTHS.