Securing a stable supply of critical raw metals: — Efforts and issues for the securement of rare-earth resources —@@@―レアアース資源確保のための取り組みと課題―

−16− Synthesiology English edition Vol.9 No.1 pp.16-26 (Jun. 2016) plus Scandium (Sc) and Yttr ium (Y). The lanthanide elements with atomic weight lighter than Europium (Eu) are called light rare earth elements, while those that are heavier are called heavy rare elements. The light rare earths are used in fluorescent materials, glass abrasive, oxygen scavengers for iron and steel, Ni-H batteries, oil refinement catalysts, and others. The heavy rare earths are mainly used in highperformance magnets.