テルビウム,削り状 化学特性,用途語,生産方法
外観
銀灰色の塊
溶解性
酸水溶液とは速やかに、水とは徐々に反応してTb(3+)となる。塩酸に溶ける。
解説
Tb．原子番号65の元素．電子配置[Xe]4f 96s2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．安定核種は質量数159のみの単核種元素．質量数135～171の放射性同位体が知られている．1843年，C.G. Mosanderによりイットリア中から分離された．元素名は鉱物yttriaの見いだされた村名ytterbyからであるが，かれはこの名前を三分割してyttria中に発見した三元素の名称をyttrium，terbium，erbiumとした．確認に手間どり1878年に最終的に確定した名称テルビウムはかれが当初エルビウムとよんだ元素に与えられた．希土類元素中とくに存在量が少ない．ガドリン石，セル石に含まれる．地殻中の存在度0.6 ppm は希土類元素中で非常に低い部類に属する．希土類元素全般の主要産出国は中国で約98％(2006年)を占めており，テルビウムなどの中重希土類は華南地域に集中している．いちじるしく寡占度の高い重要資源である．銀灰色の金属．六方最密構造(α変態)，－53 ℃ 以上で斜方晶系，1317 ℃ 以上で体心立方格子構造．融点1356 ℃，沸点3123 ℃．密度8.229 g cm－3(20 ℃)．第一イオン化エネルギー5.864 eV．水に徐々に溶解，熱水，酸には溶解して水素を発生する．酸化数3，4．化合物の色は無色．強い常磁性を示す．電子配置は Tb3＋ は4f 8，Tb4＋ はf軌道が半分満たされた4f 7で，[Xe]配置の Ce4＋ ほどに安定ではない．TbⅢ化合物が主で，TbⅣ化合物はあまり知られていない．TbⅣ F4はTbⅢ F3と F2 を300 ℃ 以上で反応させると得られる無色の固体．TbⅣ O2はTbⅢ2O3を450 ℃ で原子状酸素と反応させると得られる．Tb4O7は七酸化二テルビウム(Ⅳ)二テルビウム(Ⅲ)とされている．Tbはブラウン管他用緑色蛍光体賦活剤として，TbDyFe合金は超磁気伸縮性材料でプリンターヘッドに，TbFeCo合金は磁気光学記録材料として用いられる．現在，もっとも重要な用途はネオジム磁石([別用語参照]希土類磁石)の保磁力を高め高温特性を改善するための添加剤で，ネオジム磁石需要の急増に伴って価格が急騰している．森北出版「化学辞典（第2版）
存在
周期表3族，希土類元素でランタノイド元素の1つ。通常モナズ石，ガドリン石などの希土類鉱物中に他の希土類元素に随伴して少量産出する。地殻における平均存在量 0.9ppm，海水中の存在量は確定されていない。 1843年スウェーデンの化学者 C.モサンデルが発見した。単体は銀灰色の金属で，融点約 1356℃，比重 8.277。
用途
新素材研究用。
使用上の注意
本品はスピンドル油に浸漬されている。
化学的特性
silvery-white chip or ingot, or grey powder
物理的性質
There are two allotropic (crystal forms) of terbium, both of which are dependent on itstemperature. The alpha ((α) form exists at room temperatures and up to temperatures of1,298°C, and the beta (β) form exists beyond these temperatures. Although terbium is a silverymetal that resembles aluminum and feels like lead, it is much heavier than either of thesetwo elements. It is placed in the yttrium subgroup (lanthanide series) of the rare-earths. It isalso resistant to corrosion.
Its melting point is 1,356.9°C, its boiling point is 3,230°C, and its density is 8.23g/cm
3.
同位体
There are a total of 52 isotopes of terbium, and only one of these is stable (Tb-159). Terbium-59 makes up 100% of the element found in the Earth’s crust.
名前の由来
Named for a village in Sweden.
天然物の起源
Of all the 17 rare-earths in the lanthanide series, terbium is number 14 in abundance.Terbium can be separated from the minerals xenotime (YPO
4) and euxenite, a mixture of thefollowing: (Y, Ca, Er, La, Ce, Y, Th)(Nb, Ta, Ti
2O
6). It is obtained in commercial amountfrom monazite sand by the ion-exchange process. Monazite may contain as much as 50%rare-earth elements, and about 0.03% of this is terbium.
来歴
Discovered by Mosander in 1843. Terbium is a member of the lanthanide or “rare earth” group of elements. It is found in cerite, gadolinite, and other minerals along with other rare earths. It is recovered commercially from monazite in which it is present to the extent of 0.03%, from xenotime, and from euxenite, a complex oxide containing 1% or more of terbia. Terbium has been isolated only in recent years with the development of ion-exchange techniques for separating the rareearth elements. As with other rare earths, it can be produced by reducing the anhydrous chloride or fluoride with calcium metal in a tantalum crucible. Calcium and tantalum impurities can be removed by vacuum remelting. Other methods of isolation are possible. Terbium is reasonably stable in air. It is a silver-gray metal, and is malleable, ductile, and soft enough to be cut with a knife. Two crystal modifications exist, with a transformation temperature of 1289°C. Forty-two isotopes and isomers are recognized. The oxide is a chocolate or dark maroon color. Sodium terbium borate is used as a laser material and emits coherent light at 0.546 μm. Terbium is used to dope calcium fluoride, calcium tungstate, and strontium molybdate, used in solid-state devices. The oxide has potential application as an activator for green phosphors used in color TV tubes. It can be used with ZrO2 as a crystal stabilizer of fuel cells that operate at elevated temperature. Few other uses have been found. The element is priced at about $40/g (99.9%). Little is known of the toxicity of terbium. It should be handled with care as with other lanthanide elements.
特性
Terbium is not found in great quantities on Earth. In fact, minerals where terbium is foundcontain about 0.03% terbium. Not much of the stable isotope is found as a free metal; rathermost of it is mixed with other rare-earths or are in compound forms.
使用
There are few uses for terbium. However, terbium can be used as an activator for greenphosphor in TV tubes, and some of its compounds are used to produce laser lights. It is alsoused to “dope” (coat) some forms of solid-state instruments, as a stabilizer in fuel cells so thatthey can operate at high temperatures, and as a metal for control rods in nuclear reactors.
製造方法
Terbium is recovered from the minerals, monazite, xenotime, and euxenite. The recovery processes are quite similar to those of other lanthanide elements (See individual lanthanide elements). The metal is separated from other rareearths by ion exchange methods, which are relatively easy and faster than fractional crystallization techniques.
Terbium metal is obtained from its anhydrous trifluoride, TbF
3, or trichloride, TbCl
3, by thermal reduction with calcium, carried out in a tantalum crucible. Terbium produced by such methods may contain traces of calcium and tantalum. High purity metal can be prepared by various methods such as vacuum remelting, distillation, amalgam formation, floating zone melting, and various chemical processes.
定義
terbium: Symbol Tb. A silverymetallic element belonging to thelanthanoids; a.n. 65; r.a.m. 158.92;r.d. 8.23 (20°C); m.p. 1356°C; b.p.3123°C. It occurs in apatite and xenotime,from which it is obtained by anion-exchange process. There is onlyone natural isotope, terbium–159,which is stable. Seventeen artificialisotopes have been identified. It isused as a dopant in semiconductingdevices. It was discovered by CarlMosander (1797–1858) in 1843.
危険性
The halogens (group VIIA) of terbium are strong irritants. Most of the compounds aretoxic and some are explosive. A vacuum or inert atmosphere must be maintained when workingwith the metal because of its strong oxidation properties.
テルビウム,削り状 上流と下流の製品情報
原材料
準備製品