Y2SiO5 crystallizes in the monoclinic C2/c space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 7-coordinate geometry to one O(3), two equivalent O(1), two equivalent O(4), and two equivalent O(5) atoms. In the second Y site, Y(2) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form distorted YO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra and edges with two equivalent Y(2)O6 octahedra. Si(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share corners with four equivalent Y(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-69°. There are five inequivalent O sites. In the first O site, O(3) is bonded in a 3-coordinate geometry to one Y(1), one Y(2), and one Si(1) atom. In the second O site, O(4) is bonded in a 4-coordinate geometry to one Y(2), two equivalent Y(1), and one Si(1) atom. In the third O site, O(5) is bonded in a 3-coordinate geometry to two equivalent Y(1) and one Si(1) atom. In the fourth O site, O(1) is bonded to two equivalent Y(1) and two equivalent Y(2) atoms to form edge-sharing OY4 tetrahedra. In the fifth O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Y(2) and one Si(1) atom.
Y2SiO5 crystallizes in the monoclinic C2/c space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 7-coordinate geometry to one O(3), two equivalent O(1), two equivalent O(4), and two equivalent O(5) atoms. The Y(1)-O(3) bond length is 2.32 Å. There is one shorter (2.21 Å) and one longer (2.37 Å) Y(1)-O(1) bond length. There is one shorter (2.38 Å) and one longer (2.62 Å) Y(1)-O(4) bond length. There is one shorter (2.30 Å) and one longer (2.34 Å) Y(1)-O(5) bond length. In the second Y site, Y(2) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form distorted YO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra and edges with two equivalent Y(2)O6 octahedra. The Y(2)-O(3) bond length is 2.28 Å. The Y(2)-O(4) bond length is 2.28 Å. There is one shorter (2.21 Å) and one longer (2.30 Å) Y(2)-O(1) bond length. Both Y(2)-O(2) bond lengths are 2.28 Å. Si(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share corners with four equivalent Y(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-69°. The Si(1)-O(2) bond length is 1.63 Å. The Si(1)-O(3) bond length is 1.62 Å. The Si(1)-O(4) bond length is 1.65 Å. The Si(1)-O(5) bond length is 1.63 Å. There are five inequivalent O sites. In the first O site, O(3) is bonded in a 3-coordinate geometry to one Y(1), one Y(2), and one Si(1) atom. In the second O site, O(4) is bonded in a 4-coordinate geometry to one Y(2), two equivalent Y(1), and one Si(1) atom. In the third O site, O(5) is bonded in a 3-coordinate geometry to two equivalent Y(1) and one Si(1) atom. In the fourth O site, O(1) is bonded to two equivalent Y(1) and two equivalent Y(2) atoms to form edge-sharing OY4 tetrahedra. In the fifth O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Y(2) and one Si(1) atom.