Identifying quasi-2D and 1D electrides in yttrium and scandium chlorides via geometrical identification

Developing and understanding electron-rich electrides offers a promising opportunity for a variety of electronic and catalytic applications. Using a geometrical identification strategy, here we identify a new class of electride material, yttrium/scandium chlorides Y(Sc)Cl (y:x < 2). Anionic electrons are found in the metal octahedral framework topology. The diverse electronic dimensionality of these electrides is quantified explicitly by quasi-two-dimensional (2D) electrides for [YCl]∙e and [ScCl]∙e and one-dimensional (1D) electrides for [YCl]∙e, [ScCl]∙e, and [ScCl]∙2e with divalent metal elements (Sc: 3d and Y: 4d). The localized anionic electrons were confined within the inner-layer spaces, rather than inter-layer spaces that are observed in AB-type 2D electrides, e.g. CaN. Moreover, when hydrogen atoms are introduced into the host structures to form YClH and YClH, the generated phases transform to conventional ionic compounds but exhibited a surprising reduction of work function, arising from the increased Fermi level energy, contrary to the conventional electrides reported so far. YCl was experimentally confirmed to be a semiconductor with a band gap of 1.14 eV. These results may help to promote the rational design and discovery of new electride materials for further technological applications.