Materials Data on Fe2SiS4 by Materials Project

Fe2SiS4 is Spinel-like structured and crystallizes in the monoclinic P2/m space group. The structure is three-dimensional. there are five inequivalent Fe2+ sites. In the first Fe2+ site, Fe2+ is bonded to six S2- atoms to form FeS6 octahedra that share corners with six SiS4 tetrahedra and edges with six FeS6 octahedra. There are four shorter (2.37 Å) and two longer (2.43 Å) Fe–S bond lengths. In the second Fe2+ site, Fe2+ is bonded to six S2- atoms to form FeS6 octahedra that share corners with two equivalent SiS4 tetrahedra, edges with six FeS6 octahedra, and edges with two equivalent SiS4 tetrahedra. There are two shorter (2.25 Å) and four longer (2.31 Å) Fe–S bond lengths. In the third Fe2+ site, Fe2+ is bonded to six S2- atoms to form FeS6 octahedra that share corners with two equivalent FeS6 octahedra, corners with two SiS4 tetrahedra, edges with five FeS6 octahedra, and edges with two SiS4 tetrahedra. The corner-sharing octahedra tilt angles range from 47–50°. There are a spread of Fe–S bond distances ranging from 2.23–2.35 Å. In the fourth Fe2+ site, Fe2+ is bonded to six S2- atoms to form FeS6 octahedra that share corners with four equivalent FeS6 octahedra, corners with two equivalent SiS4 tetrahedra, edges with four equivalent FeS6 octahedra, and edges with two equivalent SiS4 tetrahedra. The corner-sharing octahedral tilt angles are 48°. There are two shorter (2.22 Å) and four longer (2.37 Å) Fe–S bond lengths. In the fifth Fe2+ site, Fe2+ is bonded to six S2- atoms to form FeS6 octahedra that share corners with twelve FeS6 octahedra and corners with six SiS4 tetrahedra. The corner-sharing octahedra tilt angles range from 47–50°. There are two shorter (2.37 Å) and four longer (2.38 Å) Fe–S bond lengths. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four S2- atoms to form SiS4 tetrahedra that share corners with six FeS6 octahedra and edges with three FeS6 octahedra. The corner-sharing octahedra tilt angles range from 2–62°. There are a spread of Si–S bond distances ranging from 2.14–2.17 Å. In the second Si4+ site, Si4+ is bonded to four S2- atoms to form SiS4 tetrahedra that share corners with six FeS6 octahedra and edges with three FeS6 octahedra. The corner-sharing octahedra tilt angles range from 1–63°. There are two shorter (2.16 Å) and two longer (2.18 Å) Si–S bond lengths. There are six inequivalent S2- sites. In the first S2- site, S2- is bonded in a see-saw-like geometry to three Fe2+ and one Si4+ atom. In the second S2- site, S2- is bonded to three Fe2+ and one Si4+ atom to form distorted corner-sharing SFe3Si tetrahedra. In the third S2- site, S2- is bonded in a see-saw-like geometry to three Fe2+ and one Si4+ atom. In the fourth S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to three Fe2+ and one Si4+ atom. In the fifth S2- site, S2- is bonded to three Fe2+ and one Si4+ atom to form corner-sharing SFe3Si tetrahedra. In the sixth S2- site, S2- is bonded in a rectangular see-saw-like geometry to three Fe2+ and one Si4+ atom.

二硫化亚铁硅（Fe₂SiS₄）具有类尖晶石（Spinel-like）结构，结晶于单斜晶系P2/m空间群，为三维空间结构。体系存在5个不等价的亚铁离子（Fe²+）位点：
1. 首个Fe²+位点：Fe²+与6个硫离子（S²-）配位形成FeS₆八面体，该八面体与6个SiS₄四面体共享顶点，同时与6个FeS₆八面体共享棱边。Fe–S键存在两种长度：4条较短键长（2.37 Å）与2条较长键长（2.43 Å）。
2. 第二个Fe²+位点：Fe²+与6个S²-配位形成FeS₆八面体，该八面体与2个等价的SiS₄四面体共享顶点，与6个FeS₆八面体共享棱边，同时与2个等价的SiS₄四面体共享棱边。Fe–S键存在两种长度：2条较短键长（2.25 Å）与4条较长键长（2.31 Å）。
3. 第三个Fe²+位点：Fe²+与6个S²-配位形成FeS₆八面体，该八面体与2个等价的FeS₆八面体共享顶点、与2个SiS₄四面体共享顶点，与5个FeS₆八面体共享棱边，同时与2个SiS₄四面体共享棱边。共顶八面体的倾斜角范围为47°~50°。Fe–S键长分布于2.23~2.35 Å区间内。
4. 第四个Fe²+位点：Fe²+与6个S²-配位形成FeS₆八面体，该八面体与4个等价的FeS₆八面体共享顶点、与2个等价的SiS₄四面体共享顶点，与4个等价的FeS₆八面体共享棱边，同时与2个等价的SiS₄四面体共享棱边。共顶八面体的倾斜角为48°。Fe–S键存在两种长度：2条较短键长（2.22 Å）与4条较长键长（2.37 Å）。
5. 第五个Fe²+位点：Fe²+与6个S²-配位形成FeS₆八面体，该八面体与12个FeS₆八面体共享顶点、与6个SiS₄四面体共享顶点。共顶八面体的倾斜角范围为47°~50°。Fe–S键存在两种长度：2条较短键长（2.37 Å）与4条较长键长（2.38 Å）。

体系存在2个不等价的硅离子（Si⁴+）位点：
1. 首个Si⁴+位点：Si⁴+与4个S²-配位形成SiS₄四面体，该四面体与6个FeS₆八面体共享顶点，同时与3个FeS₆八面体共享棱边。共顶八面体的倾斜角范围为2°~62°。Si–S键长分布于2.14~2.17 Å区间内。
2. 第二个Si⁴+位点：Si⁴+与4个S²-配位形成SiS₄四面体，该四面体与6个FeS₆八面体共享顶点，同时与3个FeS₆八面体共享棱边。共顶八面体的倾斜角范围为1°~63°。Si–S键存在两种长度：2条较短键长（2.16 Å）与2条较长键长（2.18 Å）。

体系存在6个不等价的硫离子（S²-）位点：
1. 首个S²-位点：S²-以跷跷板状几何构型与3个Fe²+和1个Si⁴+原子配位。
2. 第二个S²-位点：S²-与3个Fe²+和1个Si⁴+原子配位，形成畸变的共顶SFe₃Si四面体。
3. 第三个S²-位点：S²-以跷跷板状几何构型与3个Fe²+和1个Si⁴+原子配位。
4. 第四个S²-位点：S²-以畸变矩形跷跷板状几何构型与3个Fe²+和1个Si⁴+原子配位。
5. 第五个S²-位点：S²-与3个Fe²+和1个Si⁴+原子配位，形成共顶SFe₃Si四面体。
6. 第六个S²-位点：S²-以矩形跷跷板状几何构型与3个Fe²+和1个Si⁴+原子配位。