What is thallium used for?
Thallium has a few specialized uses, though its applications are limited due to its high toxicity:
Optics and Electronics
- Thallium is used in some special glass lenses and optical equipment due to its high refractive index and transmission of infrared light.
- It is an activator in gamma radiation detection equipment.
- Thallium salts are used in photocells and some solid-state equipment.
Alloys
- Thallium is added to lead and other alloys to lower their melting points.
- Some thallium-containing alloys are used in fire-resistant circuitry and switches.
Scientific Research
- Thallium compounds are used in certain photoelectric cells and radiation shielding.
- Thallium plays a role in modeling and studying certain chemical processes.
- Thallium sulfate was once widely used as a rodenticide and insecticide, but this use has been banned in most countries due to its toxicity.
- It has been used as a activator in specialized lamps to produce green light.
- This high purity grade is used for laboratory reagents, analytical standards and research applications that require very pure thallium.
- A slightly lower purity grade that may still have some impurities and trace elements. Used for certain specialized industrial applications.
- A raw form with higher levels of impurities like lead, zinc, cadmium. Requires further refining for most uses.
Historical Uses
Overall, while having niche scientific and industrial applications, thallium's toxic nature greatly limits its widespread use. Strict safety protocols are required when handling thallium or its compounds.
What are the different grades or purity levels for thallium metal that are commercially available?
There are a few different commercially available grades/purity levels for thallium metal, though specific details can be difficult to obtain given its limited industrial use and trade:
Reagent/Analytical Grade (Typically 99.9%+ purity)
Technical/Industrial Grade (Usually 99-99.9% purity)
Crude/Impure Grade (Potentially as low as 95-99% purity)
The highest 99.999% ultra-pure grade is also sometimes offered, but at a significant premium cost. Suppliers can also custom purify to specific grade requirements.
The main impurities found in lower purity thallium grades include other metallic elements like lead, zinc, cadmium, iron, copper and silver depending on the original source ore.
In general, higher purity commands a higher price point. But availability of consistent supply, even at lower grades, can be an issue given thallium's rarity and limited production volumes.