Europium is the most reactive of the rare earth elements. It rapidly oxidizes in air: bulk oxidation of a centimeter-sized sample occurs within several days. It resembles calcium in its reaction with water.
When added to iron, chromium, or related alloys, gadolinium greatly improves the workability and raises resistance to high temperature oxidization. It is also utilized in microwave applications, CDs, computer memory devices, MRI image enhancing, neutron radiography, and for making phosphors in TV tubes. One final use of Gadolinium comes in nuclear reactors as an emergency shut-down mechanism.
Terbium is used in colour TV tubes and fluorescent lamps as a green phosphor. In combination with Europium blue and red phosphors, the three create trichromatic fluorescent lighting, which is much brighter than conventional fluorescent lighting. Another green application for Terbium can be found in combination with neodymium for production of the world’s most heat resistant super magnets. The element is also used in alloys, crystal stabilizers in fuel cells that operate at high temperatures, specialty lasers, and to dope calcium fluoride, sodium borate and strontium molybdate materials. Terbium is a component of Terfenol-D, a material that is used in transducers, high-precision liquid fuel injectors and in a new form of audio equipment that has the potential to revolutionize the speaker industry.
Dysprosium’s thermal neutron absorption cross-section and high melting point enable it to be used in nuclear control applications. The element can be added to Neodymium-Iron-Boron magnets to raise the strength and corrosion resistance of applications like drive motors for hybrid electric vehicles. Like terbium, dysprosium is a component of Terfenol-D; a very promising material for future technology applications. It is also used in CDs, chemical reaction testing, laser materials, and dosimeters.
Holmium has one of the highest known magnetic moments. The element is imperative in the creation of the strongest, artificially generated magnetic fields. Holmium is also used in nuclear control rods, solid-state lasers in eye-safe medical and dental microwave equipment, and as a yellow and red glass, and cubic zirconia colorant.
Erbium is used in neutron-absorbing control rods, creating lasers for cutting and welding, and as a doping agent for optical fibers. As an alloy additive, Erbium lowers the hardness and improves the workability of numerous metals. In oxide form, the element is used as a pink colorant in glass and porcelain enamel glazes, and it is often used in photographic filters.
Thulium is the 2nd rarest of REEs, only next to Promethium, which almost does not occur naturally in the earth’s crust. Because of its scarcity and high price, there are few widely-used Thulium applications. Its current uses are mainly scientific experimentation, and in portable x-ray devices used for areas where electric power is not available.
Ytterbium is used in solar cells, optical glasses, crystals, and ceramics. It can be utilized as a doping material for high power solid-state lasers and as an alloy that helps to strengthen stainless steel. Like thulium, ytterbium is employed in portable x-ray machines where electricity is not available.
Lutetium is mainly used as a catalyst in refining petroleum, hydrogenation and polymerization processes, and in organic LEDs. Lutetium is currently being investigated as an agent for possible cancer treatments. It is also used in x-ray phosphors and computer memory devices.
Scandium is predominantly used with aluminum to form scandium-aluminum high strength lightweight alloys. This alloy has applications in the aerospace industry for plane frames and in sports such as bicycling, baseball, golf, etc… Scandium is used in high-intensity discharge (HID) lamps to provide daytime-like color for television, in lasers and in dentistry.
Yttrium has a wide range of uses with one of the most important being in the production of phosphors for energy efficient fluorescent lamps and LEDs. Yttrium compounds are used as host lattices for doping with different lanthanide cations to produce the red and the green color with Eu3+ and Tb3+ respectively. Yttrium is used in the production of a large variety of synthetic garnets which are used as microwave filters, gemstones, high power lasers used for precision cutting, welding, etching, boring and targeting. Yttrium is used to provide a high temperature corrosion resistance in cutting tools. Other uses include solid electrolytes, electrodes on high-performance spark plugs, catalysts, in aluminum and magnesium alloys, deoxidizer of non-ferrous metals, stabilizer of zirconia in jewelry and as a replacement for thorium in gas mantles for propane lanterns. It has a high melting point, it imparts shock resistance and low thermal expansion characteristics making it applicable in ceramic and glass formulas including camera lenses. In medical applications it is used for cancer and inflamed joints treatments and as high precision surgical tools.