Materials Data on Mg2SiO4 by Materials Project

Mg2SiO4 is Ilmenite-like structured and crystallizes in the monoclinic P2/m space group. The structure is three-dimensional. there are five inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with two SiO4 tetrahedra, edges with five MgO6 octahedra, and edges with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–57°. There are a spread of Mg–O bond distances ranging from 2.05–2.14 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with four equivalent MgO6 octahedra, corners with two equivalent SiO4 tetrahedra, edges with four equivalent MgO6 octahedra, and edges with two equivalent SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 55°. All Mg–O bond lengths are 2.10 Å. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with twelve MgO6 octahedra and corners with six SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 55–57°. There are two shorter (2.24 Å) and four longer (2.26 Å) Mg–O bond lengths. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six SiO4 tetrahedra and edges with six MgO6 octahedra. There are four shorter (2.32 Å) and two longer (2.33 Å) Mg–O bond lengths. In the fifth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent SiO4 tetrahedra, edges with six MgO6 octahedra, and edges with two equivalent SiO4 tetrahedra. There are four shorter (2.02 Å) and two longer (2.13 Å) Mg–O bond lengths. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with six MgO6 octahedra and edges with three MgO6 octahedra. The corner-sharing octahedra tilt angles range from 2–55°. There are a spread of Si–O bond distances ranging from 1.62–1.69 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with six MgO6 octahedra and edges with three MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–56°. There is one shorter (1.62 Å) and three longer (1.68 Å) Si–O bond length. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Mg2+ and one Si4+ atom. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Mg2+ and one Si4+ atom. In the third O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Mg2+ and one Si4+ atom. In the fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Mg2+ and one Si4+ atom. In the fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Mg2+ and one Si4+ atom. In the sixth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Mg2+ and one Si4+ atom.

硅酸镁（Mg₂SiO₄）为类钛铁矿（Ilmenite）结构，结晶于单斜晶系P2/m空间群，整体为三维骨架结构。体系中存在5个不等价的Mg²+位点：首个Mg²+位点中，Mg²+与6个O²-配位形成MgO₆八面体，该八面体与2个等价的MgO₆八面体共角、与2个SiO₄四面体共角，同时与5个MgO₆八面体共边、与2个SiO₄四面体共边。共角八面体的倾斜角范围为56°~57°，Mg-O键长分布于2.05~2.14 Å之间。第二个Mg²+位点中，Mg²+与6个O²-配位形成MgO₆八面体，该八面体与4个等价的MgO₆八面体共角、与2个等价的SiO₄四面体共角，同时与4个等价的MgO₆八面体共边、与2个等价的SiO₄四面体共边。共角八面体的倾斜角为55°，所有Mg-O键长均为2.10 Å。第三个Mg²+位点中，Mg²+与6个O²-配位形成MgO₆八面体，该八面体与12个MgO₆八面体共角、与6个SiO₄四面体共角。共角八面体的倾斜角范围为55°~57°，Mg-O键长包含2个较短键长（2.24 Å）与4个较长键长（2.26 Å）。第四个Mg²+位点中，Mg²+与6个O²-配位形成MgO₆八面体，该八面体与6个SiO₄四面体共角、与6个MgO₆八面体共边。Mg-O键长包含4个较短键长（2.32 Å）与2个较长键长（2.33 Å）。第五个Mg²+位点中，Mg²+与6个O²-配位形成MgO₆八面体，该八面体与2个等价的SiO₄四面体共角、与6个MgO₆八面体共边，同时与2个等价的SiO₄四面体共边。Mg-O键长包含4个较短键长（2.02 Å）与2个较长键长（2.13 Å）。体系中存在2个不等价的Si⁴+位点：首个Si⁴+位点中，Si⁴+与4个O²-配位形成SiO₄四面体，该四面体与6个MgO₆八面体共角、与3个MgO₆八面体共边。共角八面体的倾斜角范围为2°~55°，Si-O键长分布于1.62~1.69 Å之间。第二个Si⁴+位点中，Si⁴+与4个O²-配位形成SiO₄四面体，该四面体与6个MgO₆八面体共角、与3个MgO₆八面体共边。共角八面体的倾斜角范围为0°~56°，Si-O键长包含1个较短键长（1.62 Å）与3个较长键长（1.68 Å）。体系中存在6个不等价的O²-位点，所有O²-均以矩形跷跷板型配位几何与3个Mg²+和1个Si⁴+原子结合。