NaKSi2O5 crystallizes in the monoclinic P2_1/c space group. K(1) is bonded in a 6-coordinate geometry to one O(3), one O(5), two equivalent O(2), and two equivalent O(4) atoms. Na(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(5), and three equivalent O(3) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form corner-sharing SiO4 tetrahedra. In the second Si site, Si(2) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form corner-sharing SiO4 tetrahedra. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Na(1), one Si(1), and one Si(2) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to two equivalent K(1), one Na(1), and one Si(2) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one K(1), three equivalent Na(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to two equivalent K(1), one Si(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to one K(1), one Na(1), one Si(1), and one Si(2) atom.
NaKSi2O5 crystallizes in the monoclinic P2_1/c space group. K(1) is bonded in a 6-coordinate geometry to one O(3), one O(5), two equivalent O(2), and two equivalent O(4) atoms. The K(1)-O(3) bond length is 2.85 Å. The K(1)-O(5) bond length is 2.97 Å. There is one shorter (2.80 Å) and one longer (2.97 Å) K(1)-O(2) bond length. There is one shorter (2.89 Å) and one longer (3.11 Å) K(1)-O(4) bond length. Na(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(5), and three equivalent O(3) atoms. The Na(1)-O(1) bond length is 2.43 Å. The Na(1)-O(2) bond length is 2.29 Å. The Na(1)-O(5) bond length is 2.70 Å. There are a spread of Na(1)-O(3) bond distances ranging from 2.38-2.63 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form corner-sharing SiO4 tetrahedra. The Si(1)-O(1) bond length is 1.66 Å. The Si(1)-O(3) bond length is 1.59 Å. The Si(1)-O(4) bond length is 1.66 Å. The Si(1)-O(5) bond length is 1.67 Å. In the second Si site, Si(2) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form corner-sharing SiO4 tetrahedra. The Si(2)-O(1) bond length is 1.66 Å. The Si(2)-O(2) bond length is 1.58 Å. The Si(2)-O(4) bond length is 1.67 Å. The Si(2)-O(5) bond length is 1.68 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Na(1), one Si(1), and one Si(2) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to two equivalent K(1), one Na(1), and one Si(2) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one K(1), three equivalent Na(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to two equivalent K(1), one Si(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to one K(1), one Na(1), one Si(1), and one Si(2) atom.