Materials Data on Mg2SiSe4 by Materials Project

Mg2SiSe4 is Spinel-like structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six Se2- atoms to form MgSe6 octahedra that share corners with four equivalent MgSe6 octahedra, corners with two equivalent SiSe4 tetrahedra, edges with four MgSe6 octahedra, and edges with two equivalent SiSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 52–59°. There are a spread of Mg–Se bond distances ranging from 2.71–2.77 Å. In the second Mg2+ site, Mg2+ is bonded to six Se2- atoms to form MgSe6 octahedra that share corners with eight MgSe6 octahedra, corners with four equivalent SiSe4 tetrahedra, edges with two equivalent MgSe6 octahedra, and an edgeedge with one SiSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 48–59°. There are a spread of Mg–Se bond distances ranging from 2.72–2.79 Å. Si4+ is bonded to four Se2- atoms to form SiSe4 tetrahedra that share corners with six MgSe6 octahedra and edges with three MgSe6 octahedra. The corner-sharing octahedra tilt angles range from 58–59°. There are one shorter (2.28 Å) and three longer (2.31 Å) Si–Se bond lengths. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to three Mg2+ and one Si4+ atom to form distorted corner-sharing SeMg3Si trigonal pyramids. In the second Se2- site, Se2- is bonded in a rectangular see-saw-like geometry to three Mg2+ and one Si4+ atom. In the third Se2- site, Se2- is bonded in a rectangular see-saw-like geometry to three Mg2+ and one Si4+ atom.

Mg₂SiSe₄为尖晶石型结构，结晶于正交晶系Pnma空间群，其结构为三维骨架。存在两个不等价的Mg²+位点。在第一个Mg²+位点中，Mg²+与6个Se²-配位形成MgSe₆八面体，该八面体与4个等价的MgSe₆八面体共享顶角、与2个等价的SiSe₄四面体共享顶角，同时与4个MgSe₆八面体共享棱边、与2个等价的SiSe₄四面体共享棱边。共角八面体的倾斜角范围为52°~59°，Mg-Se键长分布在2.71~2.77 Å之间。在第二个Mg²+位点中，Mg²+与6个Se²-配位形成MgSe₆八面体，该八面体与8个MgSe₆八面体共享顶角、与4个等价的SiSe₄四面体共享顶角，同时与2个等价的MgSe₆八面体共享棱边、与1个SiSe₄四面体共享棱边。共角八面体的倾斜角范围为48°~59°，Mg-Se键长分布在2.72~2.79 Å之间。Si⁴+与4个Se²-配位形成SiSe₄四面体，该四面体与6个MgSe₆八面体共享顶角、与3个MgSe₆八面体共享棱边。共角八面体的倾斜角范围为58°~59°，Si-Se键长包含1个较短的2.28 Å与3个较长的2.31 Å。存在三个不等价的Se²-位点。在第一个Se²-位点中，Se²-与3个Mg²+及1个Si⁴+配位，形成畸变的共角SeMg₃Si三角锥结构。在第二个Se²-位点中，Se²-以矩形跷跷板状配位几何模式与3个Mg²+及1个Si⁴+成键。在第三个Se²-位点中，Se²-同样以矩形跷跷板状配位几何模式与3个Mg²+及1个Si⁴+成键。