Glass Compounds

• Coloring and Lightening Glass
• Optical
• Filtering Rays
• Gass for Laser Application
• Fiber Optics

The glass industry is a very large consumer of Rare Earths, bringing their diverse properties into play in various domains.

• Coloring and Lightening Glass

Cerium makes it possible to eliminate the blue-green color of ordinary glass caused by iron. In fact, the oxidizing power of tetravalent cerium is beneficial in transforming intense blue bivalent iron into very pale yellow trivalent iron, which makes it possible to decrease the color triggered by this impurity, which is frequently found in primary products for glass formulations.

This chemical lightening process may be accomplished by using neodymium or erbium to physically lighten, as they absorb ferric iron's yellow color.

Neodymium, praseodymium, erbium and cerium are also used for coloration in art glass and crystal.

• Optical

Lanthanum oxide gives borate glass exceptional transparency and a very high refraction index. Glass compounds containing lanthanum are, therefore, used universally in precision optics to make lenses (microscope, telescope) and other photograph and camera components. Yttrium and gadolinium are also used in optical glass as stabilizers to prevent glass containing lanthanum from recrystallizing.

• Filtering Rays

Cerium oxide is used in the manufacture of stable glass for filtration (protection against electronic, UV rays, etc.).

Cerium (IV) is an anti-browning agent used extensively in glass subject to high energy radiation: Ce 4+ ions, acting as traps for the electrons freed by radiation, are transformed into almost colorless Ce 3+ ions, thereby preventing formation of the colored centers responsible for browning. The best example of this, revealing both the chemical and physical properties, is the use of a small quantity of cerium (approximately 0.3 %) to prevent the faces of television sets from blackening from the effect of cathode ray bombardment. Cerium is also used identically to stabilize the glass used in the nuclear industry.

• Glass for Laser Application

Glass doped with neodymium is used in powerful lasers. Laser glass requires Rare Earths of extremely high purity.

• Fiber Optics

Rare Earths in very low amounts (a few ppm), such as the erbium in glass used in fiber optics, have the property of transmitting and amplifying information. The purity required is 99.999 %.

• Contacts

If you would like more informations, please contact:
ec-omarkets@eu.rhodia.com