High-pressure synthesis methods offer an effective way to incorporate larger cations in the truncated octahedron cage in RB12. The valence fluctuation of cerium reduces the cationic radius and thus reduces the formation pressure. The cage structure internally filling of valence shell of lanthanide ions exhibits a variety of physical properties in RB12. The synthesis of the unexplored lanthanide dodecaborides may open a way for the findings of their peculiar physical properties. Dr. Hitoshi YUSA (NIMS RFMC HPG), Prof. Fumitohi IGA (Ibaraki Univ.) and Dr. Hiroshi FUJIHISA (AIST) contributed this article.
