The main sources for ytterbium extraction are bastnäsite and monazite deposits. These are primarily mined in China, with smaller-scale mining also occurring in the USA, Australia, and Southeast Asia.

The demand for ytterbium is growing due to its use in a variety of technologies.

Ytterbium production is almost exclusively concentrated in China.

Ytterbium is obtained through solvent extraction. For this process, the rare earth oxide (REO) mixture is dissolved in hydrochloric acid, and the solution is pumped through a series of mixer-settler units. At each stage, an organic solvent is added that selectively binds a specific rare earth element.

Due to slight differences in the acidity of the ions, the various elements move through the cascade at different rates.

Ytterbium accumulates in the later stages of the extraction cascade.

The result of this step is highly pure ytterbium(III) oxide (Yb₂O₃).

To produce metallic ytterbium, the oxide is usually reduced metallothermically using lanthanum or cerium.

The metal obtained by reduction is often not pure enough for high-tech applications. The most important purification method is in-situ distillation.

One of the key drivers for ytterbium demand is the expansion of fiber optic networks and 5G. Ytterbium plays a crucial role in high-performance semiconductors and ytterbium-doped fiber amplifiers (YDFAs). Ytterbium-based amplifiers, an essential component in fiber lasers, enable efficient high-speed data transmission in communication technologies.

Another important application of ytterbium is in medical technologies. Ytterbium isotopes are used in medical imaging, radiation therapy, and surgical lasers.

Ytterbium demand could further increase in the future due to innovations in emerging fields such as quantum computing and ultra-precise atomic clocks.

Thulium is the rarest of the naturally occurring lanthanides and the second rarest among the rare earth metals, making it correspondingly expensive. Its abundance in the Earth's crust is estimated at about 0,5 ppm.

The main host minerals for thulium are monazite and xenotime.

Xenotime, which is particularly rich in heavy rare earth elements, contains a somewhat higher concentration of thulium than bastnäsite and monazite.

Thulium is obtained through solvent extraction. For this process, the rare earth oxide (REO) mixture is dissolved in hydrochloric acid, and the solution is pumped through a series of mixer-settler units. At each stage, an organic solvent is added that selectively binds a specific rare earth element.

Due to slight differences in the acidity of the ions, the various elements move through the cascade at different rates.

Thulium, being one of the heavier lanthanides, accumulates in the later stages of the extraction cascade.

The result of this step is highly pure thulium(III) oxide (Tm₂O₃), also known as “thulia.”

To obtain metallic thulium, the oxide is usually reduced metallothermically using lanthanum or cerium.

The metal produced by reduction is often not pure enough for high-tech applications. The most important purification method is vacuum distillation.

Compared to other rare earth elements, the demand for thulium is limited and its applications are confined to niche areas.

The most important use of thulium is in portable X-ray devices. When thulium-169 is irradiated, it produces thulium-170. This isotope serves as a highly efficient, portable, and safe source of soft gamma radiation, similar to that used in X-ray equipment. Since these radiation sources require no external power supply or complex cooling, they are ideal for portable X-ray devices used in non-destructive testing (e.g., weld inspection) at hard-to-reach locations such as pipelines or construction sites, as well as for medical applications in remote areas without electricity.

Another application of thulium is in high-power lasers. Thulium-doped solid-state lasers (e.g., using YAG or YLF crystals), employed in medical surgery and LIDAR (Light Detection and Ranging) systems, are extremely powerful and efficient.

Thulium is also used as a dopant in specialized phosphors and has niche applications in materials research.

Furthermore, thulium’s excellent performance in high-temperature superconductors makes it indispensable for the development of advanced electronic devices. It contributes to the production of highly efficient lasers, especially those operating in the infrared spectrum, which are crucial for precision surgical instruments and industrial applications.

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.