Applications

The lanthanoid compounds are present in every household — inside colour television tubes. When electrons are bombarded on certain mixed lanthanoid compounds, they emit visible light over a small wavelength range. Therefore the inside surface of a television tube or computer monitor is coated with tiny patches of three different lanthanoid compositions, to give three colours that make the colour image. For example, a mixed oxide of europium and yttrium, $\mathrm{(Eu,Y)_2O_3}$, releases an intense red colour when bombarded with high energy electrons.

The optoelectronics applications use lanthanoid ions as active ions in luminescent materials. The most notable application is the Nd: YAG laser (Nd: YAG = neodymium doped yttrium aluminium garnet). Erbium-doped fibre amplifiers are significant devices in optical-fibre communication systems. Lanthanoids are used in hybrid cars, superconductors and permanent magnets. …