Materials Data on Pr9Al5Se21 by Materials Project

Pr9Al5Se21 crystallizes in the trigonal R3 space group. The structure is three-dimensional. there are six inequivalent Pr3+ sites. In the first Pr3+ site, Pr3+ is bonded in a 7-coordinate geometry to seven Se2- atoms. There are a spread of Pr–Se bond distances ranging from 3.00–3.19 Å. In the second Pr3+ site, Pr3+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of Pr–Se bond distances ranging from 2.98–3.36 Å. In the third Pr3+ site, Pr3+ is bonded in a 7-coordinate geometry to seven Se2- atoms. There are a spread of Pr–Se bond distances ranging from 2.98–3.30 Å. In the fourth Pr3+ site, Pr3+ is bonded in a 7-coordinate geometry to seven Se2- atoms. There are a spread of Pr–Se bond distances ranging from 2.97–3.19 Å. In the fifth Pr3+ site, Pr3+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of Pr–Se bond distances ranging from 2.98–3.35 Å. In the sixth Pr3+ site, Pr3+ is bonded in a 7-coordinate geometry to seven Se2- atoms. There are a spread of Pr–Se bond distances ranging from 3.00–3.32 Å. There are six inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded in a tetrahedral geometry to four Se2- atoms. There are a spread of Al–Se bond distances ranging from 2.36–2.40 Å. In the second Al3+ site, Al3+ is bonded in a tetrahedral geometry to four Se2- atoms. There are a spread of Al–Se bond distances ranging from 2.36–2.40 Å. In the third Al3+ site, Al3+ is bonded to six Se2- atoms to form face-sharing AlSe6 octahedra. There are three shorter (2.59 Å) and three longer (2.67 Å) Al–Se bond lengths. In the fourth Al3+ site, Al3+ is bonded to six Se2- atoms to form distorted face-sharing AlSe6 octahedra. There are three shorter (2.49 Å) and three longer (2.82 Å) Al–Se bond lengths. In the fifth Al3+ site, Al3+ is bonded to six Se2- atoms to form distorted face-sharing AlSe6 octahedra. There are three shorter (2.49 Å) and three longer (2.83 Å) Al–Se bond lengths. In the sixth Al3+ site, Al3+ is bonded to six Se2- atoms to form face-sharing AlSe6 octahedra. There are three shorter (2.59 Å) and three longer (2.66 Å) Al–Se bond lengths. There are fourteen inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to three Pr3+ and one Al3+ atom to form distorted SePr3Al tetrahedra that share corners with three SePr3Al2 square pyramids and corners with three SePr3Al trigonal pyramids. In the second Se2- site, Se2- is bonded to three Pr3+ and one Al3+ atom to form distorted SePr3Al tetrahedra that share corners with three SePr3Al2 square pyramids and corners with three SePr3Al trigonal pyramids. In the third Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to three Pr3+ and one Al3+ atom. In the fourth Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to three Pr3+ and one Al3+ atom. In the fifth Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to three Pr3+ and one Al3+ atom. In the sixth Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to three Pr3+ and one Al3+ atom. In the seventh Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to three Pr3+ and one Al3+ atom. In the eighth Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to three Pr3+ and one Al3+ atom. In the ninth Se2- site, Se2- is bonded in a 5-coordinate geometry to four Pr3+ and one Al3+ atom. In the tenth Se2- site, Se2- is bonded to three Pr3+ and two Al3+ atoms to form distorted SePr3Al2 square pyramids that share corners with three SePr3Al tetrahedra, a cornercorner with one SePr3Al trigonal pyramid, edges with two equivalent SePr3Al trigonal pyramids, and faces with two equivalent SePr3Al2 square pyramids. In the eleventh Se2- site, Se2- is bonded to three Pr3+ and one Al3+ atom to form distorted SePr3Al trigonal pyramids that share a cornercorner with one SePr3Al2 square pyramid, corners with three SePr3Al tetrahedra, edges with two equivalent SePr3Al2 square pyramids, and edges with two equivalent SePr3Al trigonal pyramids. In the twelfth Se2- site, Se2- is bonded to three Pr3+ and two Al3+ atoms to form distorted SePr3Al2 square pyramids that share corners with three SePr3Al tetrahedra, a cornercorner with one SePr3Al trigonal pyramid, edges with two equivalent SePr3Al trigonal pyramids, and faces with two equivalent SePr3Al2 square pyramids. In the thirteenth Se2- site, Se2- is bonded to three Pr3+ and one Al3+ atom to form distorted SePr3Al trigonal pyramids that share a cornercorner with one SePr3Al2 square pyramid, corners with three SePr3Al tetrahedra, edges with two equivalent SePr3Al2 square pyramids, and edges with two equivalent SePr3Al trigonal pyramids. In the fourteenth Se2- site, Se2- is bonded in a 5-coordinate geometry to four Pr3+ and one Al3+ atom.

Pr₉Al₅Se₂₁ 晶体属于三方晶系R3空间群（trigonal R3 space group），其结构为三维骨架结构。存在6个非等效的Pr³+位点。在第一个Pr³+位点中，Pr³+采取7配位几何构型，与7个Se²-原子成键，Pr-Se键长分布范围为3.00~3.19 Å。在第二个Pr³+位点中，Pr³+采取8配位几何构型，与8个Se²-原子成键，Pr-Se键长分布范围为2.98~3.36 Å。在第三个Pr³+位点中，Pr³+采取7配位几何构型，与7个Se²-原子成键，Pr-Se键长分布范围为2.98~3.30 Å。在第四个Pr³+位点中，Pr³+采取7配位几何构型，与7个Se²-原子成键，Pr-Se键长分布范围为2.97~3.19 Å。在第五个Pr³+位点中，Pr³+采取8配位几何构型，与8个Se²-原子成键，Pr-Se键长分布范围为2.98~3.35 Å。在第六个Pr³+位点中，Pr³+采取7配位几何构型，与7个Se²-原子成键，Pr-Se键长分布范围为3.00~3.32 Å。
存在6个非等效的Al³+位点。在第一个Al³+位点中，Al³+采取四面体几何构型，与4个Se²-原子成键，Al-Se键长分布范围为2.36~2.40 Å。在第二个Al³+位点中，Al³+采取四面体几何构型，与4个Se²-原子成键，Al-Se键长分布范围为2.36~2.40 Å。在第三个Al³+位点中，Al³+与6个Se²-原子成键，形成面共享型AlSe₆八面体，其中存在3条较短（2.59 Å）和3条较长（2.67 Å）的Al-Se键长。在第四个Al³+位点中，Al³+与6个Se²-原子成键，形成畸变面共享型AlSe₆八面体，其中存在3条较短（2.49 Å）和3条较长（2.82 Å）的Al-Se键长。在第五个Al³+位点中，Al³+与6个Se²-原子成键，形成畸变面共享型AlSe₆八面体，其中存在3条较短（2.49 Å）和3条较长（2.83 Å）的Al-Se键长。在第六个Al³+位点中，Al³+与6个Se²-原子成键，形成面共享型AlSe₆八面体，其中存在3条较短（2.59 Å）和3条较长（2.66 Å）的Al-Se键长。
存在14个非等效的Se²-位点。在第一个Se²-位点中，Se²-与3个Pr³+和1个Al³+原子成键，形成畸变SePr₃Al四面体构型，该结构与3个SePr₃Al₂四方锥共享顶点，同时与3个SePr₃Al三角锥共享顶点。在第二个Se²-位点中，Se²-与3个Pr³+和1个Al³+原子成键，形成畸变SePr₃Al四面体构型，该结构与3个SePr₃Al₂四方锥共享顶点，同时与3个SePr₃Al三角锥共享顶点。在第三个Se²-位点中，Se²-采取畸变矩形跷板式配位几何构型，与3个Pr³+和1个Al³+原子成键。在第四个Se²-位点中，Se²-采取畸变矩形跷板式配位几何构型，与3个Pr³+和1个Al³+原子成键。在第五个Se²-位点中，Se²-采取畸变矩形跷板式配位几何构型，与3个Pr³+和1个Al³+原子成键。在第六个Se²-位点中，Se²-采取畸变矩形跷板式配位几何构型，与3个Pr³+和1个Al³+原子成键。在第七个Se²-位点中，Se²-采取畸变矩形跷板式配位几何构型，与3个Pr³+和1个Al³+原子成键。在第八个Se²-位点中，Se²-采取畸变矩形跷板式配位几何构型，与3个Pr³+和1个Al³+原子成键。在第九个Se²-位点中，Se²-采取5配位几何构型，与4个Pr³+和1个Al³+原子成键。在第十个Se²-位点中，Se²-与3个Pr³+和2个Al³+原子成键，形成畸变SePr₃Al₂四方锥构型，该结构与3个SePr₃Al四面体共享顶点，与1个SePr₃Al三角锥共享一组顶点对，与2个等价的SePr₃Al三角锥共享边，同时与2个等价的SePr₃Al₂四方锥共享面。在第十一个Se²-位点中，Se²-与3个Pr³+和1个Al³+原子成键，形成畸变SePr₃Al三角锥构型，该结构与1个SePr₃Al₂四方锥共享一组顶点对，与3个SePr₃Al四面体共享顶点，与2个等价的SePr₃Al₂四方锥共享边，同时与2个等价的SePr₃Al三角锥共享边。在第十二个Se²-位点中，Se²-与3个Pr³+和2个Al³+原子成键，形成畸变SePr₃Al₂四方锥构型，该结构与3个SePr₃Al四面体共享顶点，与1个SePr₃Al三角锥共享一组顶点对，与2个等价的SePr₃Al三角锥共享边，同时与2个等价的SePr₃Al₂四方锥共享面。在第十三个Se²-位点中，Se²-与3个Pr³+和1个Al³+原子成键，形成畸变SePr₃Al三角锥构型，该结构与1个SePr₃Al₂四方锥共享一组顶点对，与3个SePr₃Al四面体共享顶点，与2个等价的SePr₃Al₂四方锥共享边，同时与2个等价的SePr₃Al三角锥共享边。在第十四个Se²-位点中，Se²-采取5配位几何构型，与4个Pr³+和1个Al³+原子成键。