Materials Data on Mg3(SiO3)4 by Materials Project

Mg3Si4O12 crystallizes in the monoclinic Cc space group. The structure is two-dimensional and consists of two Mg3Si4O12 sheets oriented in the (0, 0, 1) direction. there are three inequivalent Mg sites. In the first Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with four SiO4 tetrahedra and edges with six MgO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.02–2.14 Å. In the second Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with four SiO4 tetrahedra and edges with six MgO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.02–2.14 Å. In the third Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with four SiO4 tetrahedra and edges with six MgO6 octahedra. There are two shorter (2.06 Å) and four longer (2.11 Å) Mg–O bond lengths. There are four inequivalent Si sites. In the first Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with three MgO6 octahedra and corners with three equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–58°. There is three shorter (1.64 Å) and one longer (1.65 Å) Si–O bond length. In the second Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with three MgO6 octahedra and corners with three equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–59°. There is three shorter (1.64 Å) and one longer (1.65 Å) Si–O bond length. In the third Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with three MgO6 octahedra and corners with three equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–58°. There is three shorter (1.64 Å) and one longer (1.65 Å) Si–O bond length. In the fourth Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with three MgO6 octahedra and corners with three equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–59°. There is three shorter (1.64 Å) and one longer (1.65 Å) Si–O bond length. There are twelve inequivalent O sites. In the first O site, O is bonded in a distorted rectangular see-saw-like geometry to three Mg and one Si atom. In the second O site, O is bonded in a distorted rectangular see-saw-like geometry to three Mg and one Si atom. In the third O site, O is bonded in a distorted rectangular see-saw-like geometry to three Mg and one Si atom. In the fourth O site, O is bonded in a distorted rectangular see-saw-like geometry to three Mg and one Si atom. In the fifth O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the sixth O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the seventh O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the eighth O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the ninth O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the tenth O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the eleventh O site, O is bonded in a trigonal non-coplanar geometry to three Mg atoms. In the twelfth O site, O is bonded in a trigonal non-coplanar geometry to three Mg atoms.

Mg₃Si₄O₁₂结晶于单斜晶系Cc空间群（monoclinic Cc space group）。该材料为二维结构，包含两片沿(0, 0, 1)方向取向的Mg₃Si₄O₁₂片层。体系中存在三个不等价的Mg配位位点：在第一个Mg位点中，Mg原子与6个O原子配位形成MgO₆八面体（MgO₆ octahedra），该八面体与4个SiO₄四面体（SiO₄ tetrahedra）共享顶点，同时与6个MgO₆八面体共享棱边；Mg–O键长分布范围为2.02~2.14 Å。第二个Mg位点的配位环境与第一个完全一致，其Mg–O键长同样分布于2.02~2.14 Å区间。第三个Mg位点中，Mg原子同样与6个O原子配位形成MgO₆八面体，该八面体与4个SiO₄四面体共享顶点、与6个MgO₆八面体共享棱边，此位点的Mg–O键长包含2个较短键长（2.06 Å）与4个较长键长（2.11 Å）。
体系中存在四个不等价的Si配位位点，每个位点中Si原子均与4个O原子配位形成SiO₄四面体，该四面体分别与3个MgO₆八面体及3个等价的SiO₄四面体共享顶点。其中第一、第三个Si位点对应的顶点共享八面体倾斜角范围为56°~58°，第二、第四个Si位点对应的倾斜角范围为56°~59°；所有Si位点的Si–O键长均包含3个较短键长（1.64 Å）与1个较长键长（1.65 Å）。
体系中存在十二个不等价的O配位位点：第1至第4个O位点中，O原子以畸变矩形跷跷板型配位构型分别与3个Mg原子及1个Si原子键合；第5至第10个O位点中，O原子以150°弯曲配位构型与2个Si原子键合；第11与第12个O位点中，O原子以三角非共面配位构型与3个Mg原子键合。