Materials Data on Sm8Sb3O8 by Materials Project

Sm8Sb3O8 crystallizes in the monoclinic C2 space group. The structure is three-dimensional. there are four inequivalent Sm3+ sites. In the first Sm3+ site, Sm3+ is bonded in a 4-coordinate geometry to four Sb+2.67- and four O2- atoms. There are a spread of Sm–Sb bond distances ranging from 3.42–3.60 Å. There are a spread of Sm–O bond distances ranging from 2.27–2.39 Å. In the second Sm3+ site, Sm3+ is bonded in a distorted see-saw-like geometry to two equivalent Sb+2.67- and four O2- atoms. There are one shorter (3.29 Å) and one longer (3.30 Å) Sm–Sb bond lengths. There are a spread of Sm–O bond distances ranging from 2.29–2.52 Å. In the third Sm3+ site, Sm3+ is bonded in a distorted see-saw-like geometry to two equivalent Sb+2.67- and four O2- atoms. There are one shorter (3.32 Å) and one longer (3.33 Å) Sm–Sb bond lengths. There are three shorter (2.28 Å) and one longer (2.39 Å) Sm–O bond lengths. In the fourth Sm3+ site, Sm3+ is bonded in a 3-coordinate geometry to four Sb+2.67- and three O2- atoms. There are a spread of Sm–Sb bond distances ranging from 3.37–3.52 Å. There are a spread of Sm–O bond distances ranging from 2.28–2.30 Å. There are two inequivalent Sb+2.67- sites. In the first Sb+2.67- site, Sb+2.67- is bonded in a body-centered cubic geometry to eight Sm3+ atoms. In the second Sb+2.67- site, Sb+2.67- is bonded in a body-centered cubic geometry to eight Sm3+ atoms. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to three Sm3+ atoms. In the second O2- site, O2- is bonded to four Sm3+ atoms to form a mixture of edge and corner-sharing OSm4 tetrahedra. In the third O2- site, O2- is bonded to four Sm3+ atoms to form a mixture of edge and corner-sharing OSm4 trigonal pyramids. In the fourth O2- site, O2- is bonded to four Sm3+ atoms to form a mixture of edge and corner-sharing OSm4 tetrahedra.

Sm₈Sb₃O₈晶体属于单斜晶系（monoclinic）C2空间群，其结构为三维框架结构。该晶体存在4个非等价的钐(III)（Sm³+）配位位点：
1. 第一个Sm³+位点：Sm³+采取四配位几何构型，与4个平均价态为+2.67的锑离子（Sb⁺2.67-）及4个氧离子（O²-）成键。Sm-Sb键长分布范围为3.42~3.60埃（Å，Angstrom），Sm-O键长分布范围为2.27~2.39埃。
2. 第二个Sm³+位点：Sm³+采取畸变跷跷板型配位几何（distorted see-saw-like geometry）构型，与2个等价的Sb⁺2.67-及4个O²-成键。Sm-Sb键长存在一组长短键，分别为3.29埃与3.30埃；Sm-O键长分布范围为2.29~2.52埃。
3. 第三个Sm³+位点：Sm³+采取畸变跷跷板型配位几何构型，与2个等价的Sb⁺2.67-及4个O²-成键。Sm-Sb键长分别为3.32埃与3.33埃；Sm-O键存在3条短键（2.28埃）与1条长键（2.39埃）。
4. 第四个Sm³+位点：Sm³+采取三配位几何构型，与4个Sb⁺2.67-及3个O²-原子成键。Sm-Sb键长分布范围为3.37~3.52埃，Sm-O键长分布范围为2.28~2.30埃。

该晶体存在2个非等价的Sb⁺2.67-位点：
1. 第一个Sb⁺2.67-位点：Sb⁺2.67-采取体心立方几何（body-centered cubic geometry）构型，与8个Sm³+原子成键。
2. 第二个Sb⁺2.67-位点：Sb⁺2.67-采取体心立方几何构型，与8个Sm³+原子成键。

该晶体存在4个非等价的O²-位点：
1. 第一个O²-位点：O²-采取畸变平面三角配位几何构型，与3个Sm³+原子成键。
2. 第二个O²-位点：O²-与4个Sm³+原子成键，形成兼具边共享与角共享特征的OSm₄四面体结构基元。
3. 第三个O²-位点：O²-与4个Sm³+原子成键，形成兼具边共享与角共享特征的OSm₄三角锥结构基元。
4. 第四个O²-位点：O²-与4个Sm³+原子成键，形成兼具边共享与角共享特征的OSm₄四面体结构基元。