Materials Data on Mg3(SiO3)4 by Materials Project

Mg3Si4O12 crystallizes in the triclinic P-1 space group. The structure is two-dimensional and consists of one Mg3Si4O12 sheet oriented in the (0, 0, 1) direction. there are two inequivalent Mg sites. In the first Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with four equivalent 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 equivalent SiO4 tetrahedra and edges with six equivalent MgO6 octahedra. There are two shorter (2.06 Å) and four longer (2.11 Å) Mg–O bond lengths. 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. There are six inequivalent O sites. In the first O site, O is bonded in a trigonal non-coplanar geometry to three Mg atoms. In the second O site, O is bonded in a bent 150 degrees geometry to two equivalent Si atoms. In the third O site, O is bonded in a 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. The O–Si bond length is 1.65 Å. In the fifth O site, O is bonded in a bent 150 degrees geometry to two equivalent Si atoms. In the sixth O site, O is bonded in a bent 150 degrees geometry to two equivalent Si atoms.

Mg₃Si₄O₁₂属于三斜晶系P-1空间群。该晶体为二维结构，包含一片沿(0, 0, 1)方向取向的Mg₃Si₄O₁₂晶面。体系中存在两个不等价的镁（Mg）位点。在第一个镁位点中，镁原子与六个氧（O）原子成键，形成MgO₆八面体；该八面体与四个等价的SiO₄四面体共享顶点，同时与六个MgO₆八面体共享棱边。Mg-O键的键长分布范围为2.02~2.14 Å。在第二个镁位点中，镁原子与六个氧原子成键，形成MgO₆八面体；该八面体与四个等价的SiO₄四面体共享顶点，同时与六个等价的MgO₆八面体共享棱边。该位点的Mg-O键包含两个较短键长（2.06 Å）与四个较长键长（2.11 Å）。硅（Si）原子与四个氧原子成键，形成SiO₄四面体；该四面体与三个MgO₆八面体共享顶点，同时与三个等价的SiO₄四面体共享顶点。共享顶点的八面体倾斜角范围为56°~58°。Si-O键包含三个较短键长（1.64 Å）与一个较长键长（1.65 Å）。体系中存在六个不等价的氧位点。在第一个氧位点中，氧原子以三角非共面几何构型与三个镁原子成键。在第二个氧位点中，氧原子以150°弯曲几何构型与两个等价的硅原子成键。在第三个氧位点中，氧原子以矩形跷跷板状几何构型与三个镁原子和一个硅原子成键。在第四个氧位点中，氧原子以畸变矩形跷跷板状几何构型与三个镁原子和一个硅原子成键。该位点的O-Si键长为1.65 Å。在第五个氧位点中，氧原子以150°弯曲几何构型与两个等价的硅原子成键。在第六个氧位点中，氧原子以150°弯曲几何构型与两个等价的硅原子成键。