DOE OSTI2020
(LaO)2ZnSe2 crystallizes in the orthorhombic Cmce space group. The structure is two-dimensional and consists of two LaO sheets oriented in the (1, 0, 0) direction and two ZnSe2 sheets oriented in the (1, 0, 0) direction. In each LaO sheet, there are three inequivalent La3+ sites. In the first La3+ site, La3+ is bonded in a 4-coordinate geometry to four equivalent O2- atoms. There are two shorter (2.38 Å) and two longer (2.39 Å) La–O bond lengths. In the second La3+ site, La3+ is bonded in a 4-coordinate geometry to four equivalent O2- atoms. There are two shorter (2.38 Å) and two longer (2.40 Å) La–O bond lengths. In the third La3+ site, La3+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of La–O bond distances ranging from 2.35–2.41 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four La3+ atoms to form a mixture of edge and corner-sharing OLa4 tetrahedra. In the second O2- site, O2- is bonded to four La3+ atoms to form a mixture of edge and corner-sharing OLa4 tetrahedra. In each ZnSe2 sheet, there are two inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded to four Se2- atoms to form a mixture of edge and corner-sharing ZnSe4 tetrahedra. There are two shorter (2.50 Å) and two longer (2.53 Å) Zn–Se bond lengths. In the second Zn2+ site, Zn2+ is bonded to four Se2- atoms to form corner-sharing ZnSe4 tetrahedra. All Zn–Se bond lengths are 2.51 Å. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a distorted water-like geometry to two equivalent Zn2+ atoms. In the second Se2- site, Se2- is bonded in a 2-coordinate geometry to two equivalent Zn2+ atoms. In the third Se2- site, Se2- is bonded in a distorted water-like geometry to two Zn2+ atoms.