# Hafnium, Hf

Hafnium (Hf) is a transition metal that possesses intriguing optical properties, notably its high refractive index. Although not typically used in its pure form for optical applications, hafnium is often used as an additive in various optical materials, such as in the fabrication of optical coatings. One of its most well-known applications is in hafnium oxide (HfO2), which is used as a high-index layer in anti-reflective and mirror coatings. Additionally, hafnium is employed in other specialized optical environments where its high melting point and resistance to corrosion offer advantages. Beyond optics, hafnium is widely used in the aerospace industry for its high-temperature stability, and in the nuclear industry for its high thermal neutron-absorption cross-section.

## External links

- Hafnium - Wikipedia
- Hafnium - WebElements