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)xCly (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 [Y2Cl3]+∙e−, [Sc7Cl10]+∙e−, and [Sc5Cl8]2+∙2e− with divalent metal elements (Sc2+: 3d1 and Y2+: 4d1). The localized anionic electrons were confined within the inner-layer spaces, rather than inter-layer spaces that are observed in A2B-type 2D electrides, e.g. Ca2N. Moreover, when hydrogen atoms are introduced into the host structures to form YClH and Y2Cl3H, 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. Y2Cl3 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.
Highlights
The design and synthesis of new materials with desirable properties is essential for advancing material applications and innovations, which may influence the future of technology
Using a geometrical identification strategy, here we identify a new class of electride material, yttrium/scandium chlorides Y(Sc)xCly (y:x < 2)
The localized anionic electrons were confined within the inner-layer spaces, rather than inter-layer spaces that are observed in A2B-type 2D electrides, e.g. Ca2N
Summary
The design and synthesis of new materials with desirable properties is essential for advancing material applications and innovations, which may influence the future of technology. Researchers arbitrarily alter the elemental combinations of typical electrides but retain their crystal symmetry to extend for the new electrides, e.g., ABtype, A2B-type, and A3B-type (A = alkaline or rare earth elements, B = IV, V, VI, and VII elements) electrides.[24,25,26,27] Besides, many electrides (e.g., Li,[28] Na, Mg,[30] C31, Na2He,[32] and Sr5P333) have been found to reveal a generalized structure under pressure.[34] Depending on the dimensionality of the anionic electrons localizations, electrides can be classified into 0D, 1D, and 2D systems,[13,20,35,36] where the anionic electrons are either isolated or bonded with each other in the cage-like, channel-like, or layer-like voids These interesting results suggest a geometrical way to obtain the diverse ‘interstitial spaces’ in a lattice that can stabilize excess electrons, which can provide a vast configuration space for computational discovery. The reduced rareearth halides were first reported in Gd2Cl3.44 Later, a series of
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