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

Abstract

Abstract 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) x Cl y ( 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 [Y 2 Cl 3 ] + ∙e − , [Sc 7 Cl 10 ] + ∙e − , and [Sc 5 Cl 8 ] 2+ ∙2e − with divalent metal elements (Sc 2+ : 3 d 1 and Y 2+ : 4 d 1 ). The localized anionic electrons were confined within the inner-layer spaces, rather than inter-layer spaces that are observed in A 2 B- type 2D electrides, e.g. Ca 2 N. Moreover, when hydrogen atoms are introduced into the host structures to form YClH and Y 2 Cl 3 H, 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. Y 2 Cl 3 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.