Materials Data on NaCaAlSi2O7 by Materials Project

CaNaAlSi2O7 crystallizes in the orthorhombic Cmm2 space group. The structure is three-dimensional. Na1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Na–O bond distances ranging from 2.52–2.85 Å. Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.35–2.81 Å. Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with four SiO4 tetrahedra. There is two shorter (1.77 Å) and two longer (1.78 Å) Al–O bond length. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one SiO4 tetrahedra and corners with two equivalent AlO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.60–1.69 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one SiO4 tetrahedra and corners with two equivalent AlO4 tetrahedra. There is one shorter (1.60 Å) and three longer (1.66 Å) Si–O bond length. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one Na1+, two equivalent Ca2+, and one Si4+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+, one Ca2+, and one Si4+ atom. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+ and two equivalent Si4+ atoms. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ca2+ and two equivalent Si4+ atoms. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+, one Ca2+, one Al3+, and one Si4+ atom. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+, one Ca2+, one Al3+, and one Si4+ atom.

CaNaAlSi2O7结晶于正交晶系（orthorhombic）Cmm2空间群。该结构为三维结构。Na⁺采用八配位几何构型，与8个O²⁻原子成键，Na-O键的键长分布范围为2.52~2.85埃。Ca²⁺同样采用八配位几何构型，与8个O²⁻原子成键，Ca-O键的键长分布范围为2.35~2.81埃。Al³⁺与4个O²⁻原子结合形成AlO₄四面体，该四面体与4个SiO₄四面体共享顶点。Al-O键存在2个较短键长（1.77埃）与2个较长键长（1.78埃）。体系存在2个不等价的Si⁴+位点：在第一个Si⁴+位点中，Si⁴+与4个O²⁻原子结合形成SiO₄四面体，该四面体与1个SiO₄四面体共享一个顶点，并与2个等价的AlO₄四面体共享顶点，Si-O键的键长分布范围为1.60~1.69埃。在第二个Si⁴+位点中，Si⁴+与4个O²⁻原子结合形成SiO₄四面体，该四面体与1个SiO₄四面体共享一个顶点，并与2个等价的AlO₄四面体共享顶点，Si-O键存在1个较短键长（1.60埃）与3个较长键长（1.66埃）。体系存在6个不等价的O²⁻位点：在第一个O²⁻位点中，O²⁻以畸变单键配位几何与1个Na⁺、2个等价Ca²+以及1个Si⁴+原子成键；在第二个O²⁻位点中，O²⁻以四配位几何与2个等价Na⁺、1个Ca²+以及1个Si⁴+原子成键；在第三个O²⁻位点中，O²⁻以四配位几何与2个等价Na⁺以及2个等价Si⁴+原子成键；在第四个O²⁻位点中，O²⁻以四配位几何与2个等价Ca²+以及2个等价Si⁴+原子成键；在第五个O²⁻位点中，O²⁻以二配位几何与1个Na⁺、1个Ca²+、1个Al³+以及1个Si⁴+原子成键；在第六个O²⁻位点中，O²⁻以二配位几何与1个Na⁺、1个Ca²+、1个Al³+以及1个Si⁴+原子成键。