Materials Data on UCrO9 by Materials Project
UCrO9UCrO7O2 crystallizes in the monoclinic P2_1 space group. The structure is one-dimensional and consists of two oxygen molecules; one UCrO7 ribbon oriented in the (0, 1, 0) direction; and one UCrO9 ribbon oriented in the (0, 1, 0) direction. In the UCrO7 ribbon, U is bonded in a 6-coordinate geometry to six O atoms. There are a spread of U–O bond distances ranging from 1.83–2.51 Å. Cr is bonded in a tetrahedral geometry to four O atoms. There are a spread of Cr–O bond distances ranging from 1.60–1.71 Å. There are seven inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one U atom. In the second O site, O is bonded in a bent 150 degrees geometry to one U and one Cr atom. In the third O site, O is bonded in a single-bond geometry to one U atom. In the fourth O site, O is bonded in a distorted bent 150 degrees geometry to one U and one Cr atom. In the fifth O site, O is bonded in a single-bond geometry to one U atom. In the sixth O site, O is bonded in a bent 150 degrees geometry to one U and one Cr atom. In the seventh O site, O is bonded in a single-bond geometry to one Cr atom. In the UCrO9 ribbon, U is bonded to six O atoms to form distorted UO6 octahedra that share corners with three equivalent CrO4 tetrahedra. There are a spread of U–O bond distances ranging from 1.80–2.61 Å. Cr is bonded to four O atoms to form CrO4 tetrahedra that share corners with three equivalent UO6 octahedra. The corner-sharing octahedra tilt angles range from 31–36°. There are a spread of Cr–O bond distances ranging from 1.60–1.70 Å. There are nine inequivalent O sites. In the first O site, O is bonded in a water-like geometry to one U and one O atom. The O–O bond length is 1.34 Å. In the second O site, O is bonded in a bent 120 degrees geometry to two O atoms. The O–O bond length is 1.25 Å. In the third O site, O is bonded in a single-bond geometry to one U atom. In the fourth O site, O is bonded in a single-bond geometry to one O atom. In the fifth O site, O is bonded in a bent 150 degrees geometry to one U and one Cr atom. In the sixth O site, O is bonded in a single-bond geometry to one U atom. In the seventh O site, O is bonded in a bent 150 degrees geometry to one U and one Cr atom. In the eighth O site, O is bonded in a bent 150 degrees geometry to one U and one Cr atom. In the ninth O site, O is bonded in a single-bond geometry to one Cr atom.