Tb • Atomic Number 65
Terbium
Terbium is a silvery, soft metal that belongs to the heavy rare earth elements.
Its special properties are its uniquely efficient green luminescence and extremely strong magnetostriction. These characteristics make terbium a critical and irreplaceable raw material for high-tech applications.
The discovery of terbium is as complex and unclear as that of other rare earth elements.
Carl Gustav Mosander is generally credited as the discoverer. In the early 1840s, he studied the “yttria” discovered by Johan Gadolin. However, the supposedly pure terbium compound was actually a mixture of several lanthanides. Pure terbium was only produced after 1945 with the advent of ion-exchange techniques. Mosander derived the element’s name from the Swedish mine Ytterby.
Xenotime is one of the most important sources of heavy rare earth elements. It contains significant amounts of terbium, dysprosium, and erbium.
Ion-adsorption clays are another economically important source.
China controls the mining and production of terbium and other heavy rare earth elements.
After a complex separation of other terbium-associated elements, the oxide is converted to terbium fluoride using hydrofluoric acid. It is then reduced to metallic terbium with calcium, producing calcium fluoride as a by-product. Any remaining calcium residues and impurities are removed in an additional vacuum remelting process.
Die wichtigste Anwendung von Terbium ist seine Verwendung als Aktivator für grüne Lumineszenz in Leuchtstoffen. Diese eine Anwendung ist für den Großteil der Nachfrage verantwortlich. Terbium-basierte Leuchtstoffe sind aufgrund ihrer extrem effizienten und hellen grünen Lichtemission in vielen Schlüsseltechnologien unersetzlich.
Terbium wird daher in einer Vielzahl von Beleuchtungs- und Displaytechnologien genutzt. Dazu zählen weiße LEDs, Flachbildschirme (OLEDs & Plasmadisplays), Leuchtstofflampen (Energiesparlampen).
Die zweite äußerst wichtige Anwendung ist in der Legierung Terfenol-D (eine Legierung aus Terbium, Eisen und Dysprosium). Diese Legierung zeigt den stärksten bekannten magnetostriktiven Effekt: Dieser Effekt wird in Präzisions-Aktuatoren, Schallwandlern für Sonarsysteme (Marine), Schwingungskontrollsystemen und Sensoren genutzt.
The most important application of terbium is its use as an activator for green luminescence in phosphors. This single application accounts for the majority of demand. Terbium-based phosphors are indispensable in many key technologies due to their extremely efficient and bright green light emission.
Terbium is therefore used in a wide range of lighting and display technologies, including white LEDs, flat-panel displays (OLEDs and plasma displays), and fluorescent lamps (energy-saving lamps).
The second highly important application is in the alloy Terfenol-D (an alloy of terbium, iron, and dysprosium). This alloy exhibits the strongest known magnetostrictive effect, which is utilized in precision actuators, sonar transducers (marine applications), vibration control systems, and sensors.
The silvery-gray rare earth metal terbium is ductile and malleable. Above 1315 °C, α-terbium (with an hcp crystal structure) transforms into β-terbium. Terbium is relatively stable in air, where it forms a protective oxide layer. When burned in a flame, it produces brown terbium(III,IV) oxide (Tb₄O₇). It reacts with water to form the hydroxide, releasing hydrogen gas.
Rare Earth Elements
