Lanthanides

Although the lanthanide elements, alloys, and compounds have many uses, less expensive alternatives functioning just as efficiently are used where possible. But despite their cost, the unique properties of the lanthanides do sometimes favor their use over cheaper substances, and millions of tons of lanthanides, in metallic, alloy, and compound form, are produced annually. One of the earliest uses involved an alloy of cerium and iron, called Auer metal, which produced a brilliant spark when struck. This has been widely used as a "flint" in cigarette and gas lighters. Auer metal is one of a series of mixed lanthanide alloys called misch metals that have a variety of metallurgical applications. These alloys are composed of varying amounts of the lanthanide metals, mostly cerium and smaller amounts of others such as lanthanum, neodymium, and praseodymium. They have been used to impart strength, hardness, and inertness to structural materials. They have also been used to remove oxygen and sulfur impurities from systems.

As catalysts (substances that speed up chemical reactions), the lanthanides are widely used in the oil refining industry since they speed up the conversion of crude petroleum into widely used consumer products such as gasoline. The color television industry also makes extensive use of europium and yttrium oxides to produce the red colors on television screens. Other lanthanide compounds are used in street lights, searchlights, and in the high-intensity lighting in sports stadiums. The ceramics industry uses lanthanide oxides to color ceramics and glasses. Optical lenses made with lanthanum oxide are used in cameras and binoculars. Others (Pr, Nd) are used in glass, such as in television screens, to reduce glare. Cerium oxide has been used to polish glass. The lanthanides have a variety of nuclear applications. Because they absorb neutrons, they have been used in control rods used to regulate nuclear reactors. They have also been used as shielding materials, and as structural components in reactors. Some lanthanides have unusual magnetic properties. For instance, cobalt-samarium magnets are very strong permanent magnets.