Thulium (chemical symbol Tm, atomic number 69) is one of the least abundant of the rare earth elements, but its scarcity does not diminish its importance. Though it might not be as well-known as its rare earth counterparts, thulium has unique properties that make it valuable in a variety of niche, high-tech applications. From its role in advanced medical treatments to its use in lasers and X-ray devices, thulium is a key component in technologies that are critical to modern industry and healthcare.
In this blog post, we’ll explore the discovery, properties, and growing applications of thulium, as well as the challenges and opportunities associated with this often-overlooked element.
The Discovery of Thulium
Thulium was discovered in 1879 by Swedish chemist Per Teodor Cleve, who named the element after Thule, an ancient name used to describe Scandinavia. Cleve isolated thulium from the mineral erbia by removing other rare earth elements like erbium and holmium. Thulium is one of the least abundant rare earth elements, making up only about 0.00007% of the Earth’s crust.
For many years after its discovery, thulium was seen as a scientific curiosity with few practical uses due to its rarity and high cost of extraction. However, with the advent of advanced technology and the growing demand for rare earth elements in modern applications, thulium’s unique properties have earned it a place in several important fields.
What Makes Thulium Special?
Thulium possesses several interesting characteristics that make it highly useful in specific industries:
Radioactive Isotope Production: Thulium can be transformed into a radioactive isotope (Thulium-170), which is particularly valuable in medical and industrial applications. This isotope emits X-rays, making it useful in portable X-ray devices.
Laser Applications: Thulium-doped materials are commonly used in lasers, particularly for medical and industrial uses. Thulium lasers operate at a wavelength that is highly absorbed by water, making them ideal for medical treatments involving soft tissue, where precise and controlled cutting is required.
Magnetic and Electronic Properties: Like many rare earth elements, thulium has unique magnetic and electronic properties that make it useful in certain niche applications, especially in materials that require specific magnetic behaviors at low temperatures.
Modern Uses of Thulium
Though it’s one of the rarer elements, thulium plays a critical role in several high-tech applications that touch on healthcare, industry, and scientific research. Here are some of the most important uses of thulium today:
Medical Lasers
One of the most valuable uses of thulium is in medical lasers. Thulium-doped lasers are used in a variety of minimally invasive medical procedures, particularly in urology, for treating benign prostatic hyperplasia (BPH), kidney stones, and soft tissue surgeries. Thulium lasers are prized for their precision, ability to vaporize tissue with minimal bleeding, and lower risk of damage to surrounding areas.
The specific wavelength of thulium lasers (around 2 microns) is highly absorbed by water, which makes them especially effective in surgeries involving tissues with high water content. This results in more controlled, precise cuts that reduce recovery time for patients and lead to better overall outcomes.
Portable X-Ray Devices
Thulium-170, a radioactive isotope of thulium, is used in portable X-ray machines. These devices are crucial in locations where large, stationary X-ray machines are impractical, such as in field hospitals, remote areas, or during certain industrial inspections. Thulium-170 is ideal for these uses because it emits low-energy X-rays that are safe for medical imaging and can be used for diagnostic purposes without the need for bulky equipment.
The portability of thulium-based X-ray devices makes them indispensable in emergency and military medical settings, as well as in industrial inspections for things like pipeline integrity or welding inspections, where non-destructive testing is essential.
High-Temperature Superconductors
Thulium is also being explored in the development of high-temperature superconductors, materials that can conduct electricity with zero resistance at relatively higher temperatures (compared to traditional superconductors, which require extremely low temperatures). These superconductors are critical in fields like magnetic levitation (maglev) transportation, energy storage, and MRI machines. While this is an area of ongoing research, the magnetic properties of thulium make it a candidate for improving the performance of these materials.
High-Performance Magnets
Thulium’s magnetic properties, while not as strong as other rare earth elements like neodymium or dysprosium, are useful in niche applications requiring specific magnetic characteristics. Thulium is used in specialized magnet alloys, particularly in situations where its unique properties are needed for high-performance applications at low temperatures, such as in cryogenics or advanced physics research.
Nuclear Reactors
Thulium is occasionally used in nuclear reactors as part of control rods. Control rods help regulate the fission reaction by absorbing neutrons, and thulium’s ability to absorb neutrons makes it valuable in this context. Although not as commonly used as some other elements in this role, thulium’s neutron absorption properties are useful in specialized reactor designs.
Challenges and Future Potential of Thulium
One of the biggest challenges with thulium is its rarity and the high cost of extraction. Thulium is one of the least abundant rare earth elements, which makes large-scale use difficult and expensive. Most thulium is extracted from the minerals monazite and bastnäsite, which contain very small amounts of the element, making extraction labor-intensive and costly.
However, despite these challenges, the demand for thulium is growing, particularly as its applications in medical technology and lasers expand. The miniaturization of technology, the need for portable diagnostic tools, and the growth of minimally invasive surgery techniques are all likely to drive increased demand for thulium.
Additionally, ongoing research into thulium’s role in high-temperature superconductors and advanced magnetic materials could open new avenues for its use, especially in next-generation technologies like quantum computing and green energy solutions.
Environmental and Supply Chain Considerations
Like other rare earth elements, the extraction and processing of thulium come with environmental and supply chain concerns. Rare earth mining can lead to environmental degradation, including habitat destruction, water contamination, and significant carbon emissions. Additionally, with China being the dominant producer of rare earth elements, there are concerns about supply chain stability and geopolitical dependencies.
Efforts are being made to improve the sustainability of rare earth element mining and to develop recycling programs to recover rare earth elements from discarded electronics and other products. For thulium, recycling efforts could help mitigate the challenges of its scarcity and high extraction cost, although effective recycling programs are still in development.
Conclusion
Thulium may be one of the least abundant and lesser-known rare earth elements, but its unique properties make it indispensable in several high-tech fields, particularly in medical lasers, portable X-ray devices, and advanced materials. As technology continues to evolve, thulium’s role is likely to grow, especially in the areas of minimally invasive surgery, portable diagnostics, and possibly high-temperature superconductors.
While challenges remain, particularly in terms of supply and cost, ongoing research and innovation in the field of rare earth elements could help unlock new potential uses for thulium in the future. Its quiet but essential role in modern technology ensures that this rare element will remain a valuable resource for industries ranging from healthcare to advanced manufacturing.