Properties and Overview of Thulium

Overview:

Thulium (Tm) is a rare earth element in the periodic table's lanthanide series. With an atomic number of 69, thulium is one of the least abundant rare earth metals, and it is typically found in small concentrations within minerals such as monazite and bastnäsite. Despite its rarity, thulium has niche applications due to its unique properties. Thulium is a silvery-gray metal that is relatively soft and malleable. It has a high melting point of about 1,545°C and a boiling point of around 1,950°C. Thulium has a moderate density of approximately 9.32 g/cm³. Like other lanthanides, thulium is paramagnetic at room temperature, which means an external magnetic field weakly attracts it.
Thulium is relatively reactive, especially when compared to non-metals. It slowly oxidizes in air, forming a protective oxide layer (Tm₂O₃) that prevents further corrosion. Thulium reacts with water, although the reaction is slow, producing hydrogen gas and thulium hydroxide (Tm(OH)₃). It also readily dissolves in acids, forming soluble thulium salts. In its compounds, thulium primarily exhibits the +3 oxidation state, although compounds with a +2 oxidation state are also known, though they are less stable.
Thulium is considered to have low toxicity, and its compounds are generally regarded as having low biological activity. However, as with all heavy metals, thulium compounds should be handled carefully to avoid ingestion, inhalation, or skin contact, which could cause irritation or other health issues. Due to its reactivity, thulium should be stored in airtight containers to prevent oxidation and moisture absorption. Special precautions are required when handling thulium isotopes used in medical and industrial applications, especially those that are radioactive, as they pose additional health hazards due to radiation exposure.

Production:

Thulium is produced commercially through the extraction and separation of its ore minerals. The most common sources are monazite and bastnäsite, from which thulium is extracted using solvent extraction and ion exchange techniques. The refining process is complex due to the similar chemical properties of lanthanides, which make it challenging to separate thulium from other rare earth elements. Once separated, thulium oxide (Tm₂O₃) is reduced using calcium or other reactive metals to obtain pure thulium metal.

Applications:

While thulium has limited widespread applications due to its rarity and cost, it is used in several specialized fields; Thulium is used in portable X-ray machines, particularly thulium-170, a radioactive isotope that serves as a radiation source. Thulium-doped lasers, especially in the infrared range, are valuable in medical procedures, such as laser surgery, and military applications for rangefinding and communication. Another isotope, thulium-169, is used as a source of beta particles in certain types of nuclear reactors and in experimental physics. Thulium is sometimes used to produce high-temperature superconductors, where it contributes to the materials' unique magnetic and electrical properties.

Summary:

Thulium a rare and valuable metal, plays a crucial role in advanced scientific and industrial fields. Its specialized applications, such as in medical technology and laser production, underscore its unique properties and the importance of its contributions. While not as widely used as other elements, thulium's impact in these niche areas is significant, making it a metal of great value and potential.

See a comprehensive list of atomic, electrical, mechanical, physical and thermal properties for thulium below: