Relative Atomic Mass
Terbium (Tb), one of the ‘heavy rare earths’, has grown in importance since the ongoing development of energy-efficient applications, which have become more prominent in the last few years since the beginning of what we might call the ‘green’ revolution.
The ‘heavy’ rare earths are generally rarer and hence more valuable than the ‘light’ rare earths, and by comparison, Terbium is indeed much rarer and more valuable than Neodymium, at 55th most abundant element in the earth’s crust versus Neodymium at 27th place.
Terbium is well represented among a variety of ‘green’ applications such as Hybrid-Electric Vehicle (HEV) motors. A small amount is found within permanent magnets in wind turbines/ washing machine motors/ vacuum-cleaner motors/ elevator wind-up & compressor motors and also used in energy efficient lighting, some X-ray machines and to create the green colour for plasma televisions which are coated with phosphors doped with terbium. Terbium also has a number of isotopes and salts which are used in various applications, though mainly for R&D purposes.
Finally, Terbium is also used as a dopant in lasers and semiconductors (possibly for energy efficient LED lighting). While in 2012 the price of terbium rose to around $3000, the price as of July 2014 has fallen to around $1000 per kilogram.