Samarium has a bright silver luster and is reasonably stable in air. The metal ignites in air at about 150 deg C. Thirty two isotopes and isomers of samarium are now recognized. Natural samarium is a mixture of seven isotopes, three of which are unstable but have long half-lives. The sulfide has excellent high-temperature stability and good thermoelectric efficiencies up to 1100 deg C. SmCo5 has been used in making a new permanent magnet material with the highest resistance to demagnetization of any known material. Samarium oxide has been used in optical glass to absorb the infrared.
Samarium is used to dope calcium fluoride crystals for use in optical masers or lasers.
It is used in infrared absorbing glass and as a neutron absorber in nuclear reactors.