Other Rare Earths
Most of the remaining lanthanides fall into the group known as the “heavies” and include: Samarium, Gadolinium, Dysprosium, Terbium, Holmium, Erbium, Thulium, Ytterbium, and Lutetium.

Samarium offers spectral absorption bands around 950 and 1100 nm that make it useful in filter glasses that surround Neodymium laser rods to increase operating efficiency. Alloys containing Samarium are used in high temperature stable permanent magnets that help make many devices smaller and more powerful. Samarium cobalt alloys are used in high-temperature-stable permanent magnets that are among the most powerful produced and are used in such items as miniature speakers. Samarium oxide forms stable complex titanates that have useful dielectric properties suitable for capacitors, particularly at microwave frequencies. Samarium is also used in glass and tile pigmentation.

Gadolinium’s unique magnetic behavior allows this Lanthanide to be used in alloys that form the heart of magneto-optic recording technology used for handling computer data. Many such data storage devices utilize Gadolinium. Super computers contain Gadolinium based bubble-memory crystal substrates. Magnetic resonance imaging (MRI) systems use materials containing Gadolinium to enhance the resulting images. Gadolinium is also the single most efficient component used in the detection of power plant radiation leaks.

Dysprosium is a popular heavy that helps to make electronic components smaller and faster. Dysprosium oxide is an additive in special ceramic compositions for producing high-capacitance, small-size capacitors for electronic applications. Dysprosium is also an additive for enhancing coercivity in NdFeB high-strength permanent magnets.

Terbium helps give us energy efficient fluorescent lamps and Terbium metal alloys help to provide suitable metallic films for magneto-optic recording of data.

Holmium is one of the least abundant rare earth elements and has few commercial uses.

Erbium can be found as an amplifier for fiber optic data transmission (since Erbium fortuitously loses efficiently at 1.55 microns). Lasers based on Erbium have been introduced for medical and dental uses because they are suited to energy delivery without thermal build-up in human tissue. Erbium is also used in glass coloration where its stability ensures that glass formulations using it will be colored pink. It is the only pink colorant truly stable in glass melts and is used in sunglasses and decorative crystal glassware.

Thulium, the rarest of the "rare earths", is a typical heavy lanthanide with chemistry similar to Yttrium. Its most specific property is, upon appropriate excitation, an emission in the blue. The luminescence of Tm, for example, under X-ray excitation is in the near u.v (˜375 nm) and blue (˜465 nm), closely matching the sensitivity of normal photographic film. It can be used in sensitive Xray phosphors to reduce X-ray exposure.

Ytterbium resembles Yttrium in broad chemical behavior. The metal when subject to very high stresses increases its electrical resistance by an order of magnitude and is used in stress gauges to monitor ground deformations caused, for example, by nuclear explosions.

Lutetium, the last member of the Lanthanide series is, along with thulium, the least abundant. It is recovered, by ion-exchange routines, in small quantities from yttrium-concentrates and is available as a high-purity oxide. Cerium-doped lutetium oxyorthosilicate (LSO) is currently used in detectors in positron emission tomography (PET).