- Calcium hexaboride (CaB₆) is an inorganic compound composed of calcium and boron, known for its distinctive physical and electronic properties. It typically appears as a black, crystalline, and extremely hard material with a high melting point (over 2,200 °C).
- Belonging to the class of metal hexaborides, calcium hexaboride has a cubic crystal structure that gives it notable strength, chemical stability, and electrical conductivity. These features make it valuable in advanced ceramics, thermionic materials, and various high-performance applications.
- One of the primary uses of calcium hexaboride is as a refractory material. Due to its thermal stability and hardness, it is employed in environments that demand resistance to high temperatures, abrasion, and chemical corrosion. It is particularly used in the manufacture of hot-pressed ceramics and abrasive components, as well as in protective coatings for materials exposed to extreme conditions, such as turbine components and industrial nozzles.
- In metallurgy, CaB₆ functions as a deoxidizing and desulfurizing agent, especially in aluminum and other non-ferrous metal production. It helps remove oxygen and sulfur impurities, improving metal quality and mechanical properties. Its boron content also acts as a grain refiner, aiding in the formation of fine, uniform microstructures in metal alloys, which enhances strength and workability.
- Calcium hexaboride also displays intriguing electronic and magnetic properties, which have sparked scientific interest. It is a semimetal with low carrier concentration and has been studied for possible ferromagnetism at low temperatures, especially when doped with rare-earth elements or lanthanides. These unusual magnetic properties in a non-transition metal compound have prompted research into its potential use in spintronics and quantum materials.
- Moreover, CaB₆ is being evaluated for thermionic emission applications. Due to its relatively low work function and chemical inertness, it shows promise in electron-emitting cathodes, which are used in vacuum electronics, cathode ray tubes, and certain plasma devices. Its robust emission performance at high temperatures makes it a candidate material for long-lived, high-efficiency thermionic devices.
- From a safety perspective, calcium hexaboride is relatively inert and stable, although it should be handled carefully in powder form due to potential respiratory hazards. It is resistant to most acids and oxidizing agents, which contributes to its longevity and durability in harsh chemical environments.
