Y5Si4 crystallizes in the orthorhombic Pnma space group. There are three inequivalent Y sites. In the first Y site, Y(1) is bonded in a 6-coordinate geometry to one Si(3), two equivalent Si(2), and three equivalent Si(1) atoms. In the second Y site, Y(2) is bonded to one Si(2), two equivalent Si(3), and three equivalent Si(1) atoms to form a mixture of distorted edge, face, and corner-sharing YSi6 octahedra. The corner-sharing octahedral tilt angles range from 38-45°. In the third Y site, Y(3) is bonded to two equivalent Si(1), two equivalent Si(2), and two equivalent Si(3) atoms to form a mixture of distorted face and corner-sharing YSi6 octahedra. The corner-sharing octahedral tilt angles range from 44-56°. There are three inequivalent Si sites. In the first Si site, Si(3) is bonded in a 9-coordinate geometry to two equivalent Y(1), two equivalent Y(3), four equivalent Y(2), and one Si(2) atom. In the second Si site, Si(1) is bonded in a 8-coordinate geometry to one Y(3), three equivalent Y(1), three equivalent Y(2), and one Si(1) atom. In the third Si site, Si(2) is bonded in a 9-coordinate geometry to two equivalent Y(2), two equivalent Y(3), four equivalent Y(1), and one Si(3) atom.
Y5Si4 crystallizes in the orthorhombic Pnma space group. There are three inequivalent Y sites. In the first Y site, Y(1) is bonded in a 6-coordinate geometry to one Si(3), two equivalent Si(2), and three equivalent Si(1) atoms. The Y(1)-Si(3) bond length is 3.02 Å. There is one shorter (2.93 Å) and one longer (2.96 Å) Y(1)-Si(2) bond length. There are a spread of Y(1)-Si(1) bond distances ranging from 2.87-2.96 Å. In the second Y site, Y(2) is bonded to one Si(2), two equivalent Si(3), and three equivalent Si(1) atoms to form a mixture of distorted edge, face, and corner-sharing YSi6 octahedra. The corner-sharing octahedral tilt angles range from 38-45°. The Y(2)-Si(2) bond length is 3.15 Å. There is one shorter (3.08 Å) and one longer (3.14 Å) Y(2)-Si(3) bond length. There are a spread of Y(2)-Si(1) bond distances ranging from 3.04-3.13 Å. In the third Y site, Y(3) is bonded to two equivalent Si(1), two equivalent Si(2), and two equivalent Si(3) atoms to form a mixture of distorted face and corner-sharing YSi6 octahedra. The corner-sharing octahedral tilt angles range from 44-56°. Both Y(3)-Si(1) bond lengths are 3.07 Å. There is one shorter (2.92 Å) and one longer (3.28 Å) Y(3)-Si(2) bond length. There is one shorter (2.92 Å) and one longer (2.99 Å) Y(3)-Si(3) bond length. There are three inequivalent Si sites. In the first Si site, Si(3) is bonded in a 9-coordinate geometry to two equivalent Y(1), two equivalent Y(3), four equivalent Y(2), and one Si(2) atom. The Si(3)-Si(2) bond length is 2.54 Å. In the second Si site, Si(1) is bonded in a 8-coordinate geometry to one Y(3), three equivalent Y(1), three equivalent Y(2), and one Si(1) atom. The Si(1)-Si(1) bond length is 2.46 Å. In the third Si site, Si(2) is bonded in a 9-coordinate geometry to two equivalent Y(2), two equivalent Y(3), four equivalent Y(1), and one Si(3) atom.