Beryllium (Be)

Abstract

Beryllium (Be) has many unique properties that make it of both theoretical and practical interest. As a metal, it is strikingly different both from lithium—its neighbor in the periodic table—and the higher Z alkaline-earth metals magnesium and calcium. The density of beryllium is not only 3.5 times larger than that of lithium but is also greater than that of magnesium and calcium. Its compressibility is very low, its Debye temperature is among the highest in the periodic table, its melting temperature is much higher than the other alkaline earths, and its electronic specific heat is very low. Beryllium also has many properties that recommend it for exotic optical applications. It is relatively light compared with other metals of optical importance and offers a very high specific stiffness, a low thermal expansion at cryogenic temperatures, a low Z number, high thermal conductivity, and high reflectivity in the infrared. These properties make it particularly attractive for optical components that are intended for use in space. This chapter presents a summarization of the relevant facts about the more significant studies of optical properties of Be, including photon-energy range, sample type, method of measurement, date of publication, and reference number. The chapter further discusses the available experimental data in four spectral regions—the soft X-ray range, the vacuum ultraviolet, the infrared–visible–ultraviolet, and the far infrared.