Discovery and Naming
Beryllium was discovered by French chemist and pharmacist Nicholas-Louis Vauquelin in beryl, a silicate mineral (Be3Al2Si6O18) and emerald (variety of beryl) in 1797. Later on, the element was separated in 1828 by the french chemist Antoine-Alexandre-Brutus Bussy, and by the German chemist Friedrich Wohler, independently. The salts of beryllium have a sweet taste, and hence, it was known as glucinium from greek word ‘glykys’ for “sweet”, until IUPAC declared its name as beryllium (which is derived from Greek word ‘beryllos’ for beryl). It is a chemical element with symbol ‘Be’ with atomic number 4 in the periodic table.
Beryllium is naturally found in mineral rocks, coal ashes, soil and volcanic dust. There are about 30 beryllium containing minerals, from which, the most common naturally occurring minerals are beryl and bertrandite. Beryl provides coloured gems, such as emerald (green), aquamarine (blue-green), heliodor (yellow), and morganite (pink).
It is a silver-grey, light metal, which is solid at room temperature.
Stiffness means the extent to which a metal resists deformation to the applied force. Beryllium is extremely a stiff metal. It is six times stiffer than steel, and it can maintain its shape at high and low temperature. Its elastic modulus (the quantity that measures substance’s resistance to being deformed elastically, when stress is applied to it) is about 50% greater than steel.
Melting and Boiling Point
Although it is a light metal, it melts at a higher temperature, i.e., 1287°C as compared to light metals. Its boiling point is 2468°C.
Beryllium possesses the highest thermal conductivity among all metals on an equal weight basis. Its coefficient of thermal expansion closely matches with those of stainless steel, titanium, nickel alloys, cobalt alloys and other commonly used structured materials. This makes beryllium, a suitable candidate as a mirror over a temperature range from -453°F (-249°C) to as high as 500°F (275°C), for use in satellites and other space applications.
Reactivity with Air and Water
Beryllium is kinetically inert to oxygen and water because it forms an oxide film on its surface. However, powdered beryllium burns brilliantly, when it is ignited in air, and it gives beryllium oxide (BeO) and beryllium nitride (Be3N2). The beryllium oxides have rock salt structure, which shows that it is covalent in nature. Although beryllium is placed in the alkaline earth metals group in the periodic table, its oxides and hydroxides are not alkaline in nature [Alkaline metals (Mg, Ca, Sr, Ba) are so-called because their oxides and hydroxides are alkaline in nature]. Beryllium oxide (BeO) is amphoteric in nature and beryllium hydroxide (BeOH) is also amphoteric in nature as it reacts with acid and alkali both.
Be(OH)2 + 2OH → [Be(OH)4]2 (Beryllate ion)
Be(OH)2 + 2HCl + 2H2O → [Be(OH)4]Cl2
Reactivity with Halogens
Beryllium metal combines with halogens (F, Cl, Br, I) to form its corresponding halides. The general reaction is depicted as follows:
Be + X2→ BeX2 (X= F, Cl, Br, I)
Beryllium chloride is conveniently made from its oxide at the temperature range of 600-800K; whereas, the best route for the preparation of beryllium fluoride is the thermal decomposition of (NH4)2BeF4.
BeO + C + Cl2 → BeCl2 +CO
Beryllium halides are covalent in nature and they are easily soluble in organic solvents. This property is also exceptional as compared to other group 2 members (Mg, Ca, Sr, Ba), whose halides are ionic in nature.
The reducing nature of beryllium is due to its large hydration energy, which is attributed to the small size of Be2+ ion and relatively large value of the atomization enthalpy of the metal.
Whether beryllium is barely polished or coated, it presents an excellent optical surface. The material is also reflective in the far-infrared region as high as those of gold, the usual reflective metal of choice. It is also transparent or translucent metal to most wavelengths of X-rays and gamma rays, which makes it useful for the output windows of X-ray tubes and other such apparatus.
1. Mechanical Uses
Beryllium is one of the lightest metal with unique characteristics, such as high stiffness, high strength, low density, heat resistant, and reflectivity make it an exceptional material for various industries, such as aerospace, medical, space and defence. It also offers high specific heat and excellent thermal conductivity that allows the material to sustain crucial properties at both elevated and cryogenic temperatures.
2. Beryllium Alloys
Beryllium is used in alloys with copper or nickel to make gyroscopes, springs, spot welding electrolytes and non-sparking tools. Mixing with these metals increases their electrical and thermal conductivity. Other alloys used for high-speed aircraft, missiles, spacecraft and communication satellites. Beryllium alloys are used in many applications because of their combination of elasticity, high electrical conductivity and thermal conductivity, high strength and hardness, nonmagnetic properties, as well as good corrosion and fatigue resistance.
3. Beryllium Mirrors
Beryllium exhibit low light scattering in the infrared, and it is five times stiffer than aluminium (as measured by the young’s modulus), and it can be easily matched with other metals of the similar coefficient of expansion, such as titanium or steel. It provides an excellent surface for standard IR scanning mirrors because it is highly durable, scratch-resistant and easily cleaned with acetone and tissue. Some IR scan mirrors produced years ago, have maintained 98.4% reflectivity without a change in its figure. The polished mirror surface has a fairly thick layer of beryllium oxide (BeO). Besides being stiffer than aluminium, beryllium mirrors are also lighter and more durable. These performance characteristics make beryllium a highly desirable mirror material, which makes it useful in satellites and other space applications.
4. Magnetic Applications
Beryllium is non-magnetic. Because of this, tools fabricated out of beryllium-based materials are used by naval or military explosive ordnance disposal teams for work on or near naval mines, since these mines commonly have magnetic fuzes. They are also found in maintenance and construction materials near magnetic resonance imaging (MRI) machines because of the high magnetic fields generated. In the fields of radio communications and radars, hand made beryllium tools are used, that are used to generate high levels of microwave power in the transmitters.
5. Radiation Windows
The most important application of beryllium is in radiation windows for X-ray tubes because of its low atomic number and very low absorption for X-rays. Thin beryllium foils are used as radiation windows for X-ray detectors and extremely low absorption minimizes the heating effect caused by high intensity. Vacuum-tight windows and beam-tubes for radiation experiments are manufactured exclusively from beryllium. For various X-ray emission studies, the sample holder is usually made of beryllium because its emitted X-ray have much lower energies than X-rays from most studied materials.
Beryllium is useful as a material for high-frequency speaker devices because of its low weight and high rigidity. Although, beryllium tweeters (a special type of loudspeakers) are limited to high-end home because beryllium is expensive (many more times than titanium).