Terbium is a heavy rare earth element (HREE) that is malleable and ductile. Terbium is also never found in nature as the simple substance but found in various minerals like cerite, gadolinite, monazite, xenotime, and euxenite. Almost all of the world’s mine production of Terbium is in China or Myanmar, and its refined production is concentrated in China. Although Nd2Fe14B phase provides very large energy product, remanence and coercivity, it suffers from significantly declines as temperature increases, and it not regarded as suitable for applications where the temperature is elevated.
The high-temperature properties of the material can be enhanced, however, by replacing a few percent of Neodymium with Dysprosium or Terbium. Terbium is more effective than Dysprosium in this regard, but it is more expensive because it has lower natural abundance. Terbium is generally utilized for manufacturing of double-high Neodymium magnets (high coercivity and high energy product). In order to realize rational use of rare earth resource, supply chain stability, and cost advantages, either magnet manufacturers or downstream magnet consumers have been trying to get rid of heavy rare earth elements Dysprosium and Terbium, then many HREE-less or HREE-free solution launched, especially grain boundary diffusion (GBD) technology.
