Materials Data on Pm2MgS4 by Materials Project

MgPm2S4 is Spinel-like structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Mg2+ is bonded to four S2- atoms to form MgS4 tetrahedra that share corners with six PmS6 octahedra and edges with three PmS6 octahedra. The corner-sharing octahedra tilt angles range from 59–64°. There are a spread of Mg–S bond distances ranging from 2.41–2.49 Å. There are two inequivalent Pm3+ sites. In the first Pm3+ site, Pm3+ is bonded to six S2- atoms to form PmS6 octahedra that share corners with four equivalent PmS6 octahedra, corners with two equivalent MgS4 tetrahedra, edges with four PmS6 octahedra, and edges with two equivalent MgS4 tetrahedra. The corner-sharing octahedra tilt angles range from 52–57°. There are a spread of Pm–S bond distances ranging from 2.80–2.85 Å. In the second Pm3+ site, Pm3+ is bonded to six S2- atoms to form PmS6 octahedra that share corners with eight PmS6 octahedra, corners with four equivalent MgS4 tetrahedra, edges with two equivalent PmS6 octahedra, and an edgeedge with one MgS4 tetrahedra. The corner-sharing octahedra tilt angles range from 47–57°. There are a spread of Pm–S bond distances ranging from 2.80–2.89 Å. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Pm3+ atoms. In the second S2- site, S2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Pm3+ atoms. In the third S2- site, S2- is bonded to one Mg2+ and three Pm3+ atoms to form distorted corner-sharing SPm3Mg trigonal pyramids.

MgPm₂S₄ 呈类尖晶石结构，结晶于正交晶系（orthorhombic）Pnma空间群（space group）。该晶体结构为三维框架。Mg²+与4个S²-配位形成MgS₄四面体（MgS4 tetrahedra），该四面体与6个PmS₆八面体（PmS6 octahedra）共享顶点，同时与3个PmS₆八面体共享棱边；顶点共享的八面体倾斜角范围为59°~64°。Mg—S键长分布区间为2.41~2.49 Å。体系存在两种不等价的Pm³+位点：第一种Pm³+位点中，Pm³+与6个S²-配位形成PmS₆八面体，该八面体与4个等价的PmS₆八面体共享顶点、与2个等价的MgS₄四面体共享顶点，同时与4个PmS₆八面体共享棱边、与2个等价的MgS₄四面体共享棱边；顶点共享的八面体倾斜角范围为52°~57°，Pm—S键长分布区间为2.80~2.85 Å。第二种Pm³+位点中，Pm³+与6个S²-配位形成PmS₆八面体，该八面体与8个PmS₆八面体共享顶点、与4个等价的MgS₄四面体共享顶点，同时与2个等价的PmS₆八面体共享棱边、与1个MgS₄四面体共享棱边；顶点共享的八面体倾斜角范围为47°~57°，Pm—S键长分布区间为2.80~2.89 Å。体系存在三种不等价的S²-位点：第一种S²-位点中，S²-与1个Mg²+和3个Pm³+配位，配位几何呈矩形跷跷板型（rectangular see-saw-like geometry）；第二种S²-位点中，S²-与1个Mg²+和3个Pm³+配位，配位几何同样呈矩形跷跷板型；第三种S²-位点中，S²-与1个Mg²+和3个Pm³+配位，形成畸变的、顶点共享的SPm₃Mg三角锥（trigonal pyramids）。