Materials Data on Sr2NdTlCu2O7 by Materials Project

Sr2NdCu2TlO7 crystallizes in the orthorhombic Pmm2 space group. The structure is three-dimensional. Sr2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Sr–O bond distances ranging from 2.53–2.87 Å. Nd3+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are six shorter (2.48 Å) and two longer (2.49 Å) Nd–O bond lengths. Cu2+ is bonded to five O2- atoms to form corner-sharing CuO5 square pyramids. There are a spread of Cu–O bond distances ranging from 1.94–2.27 Å. Tl3+ is bonded in a distorted see-saw-like geometry to four O2- atoms. There are two shorter (2.13 Å) and two longer (2.44 Å) Tl–O bond lengths. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 6-coordinate geometry to two equivalent Sr2+, two equivalent Nd3+, and two equivalent Cu2+ atoms. In the second O2- site, O2- is bonded in a 6-coordinate geometry to two equivalent Sr2+, two equivalent Nd3+, and two equivalent Cu2+ atoms. In the third O2- site, O2- is bonded to four equivalent Sr2+, one Cu2+, and one Tl3+ atom to form a mixture of distorted edge and corner-sharing OSr4TlCu octahedra. The corner-sharing octahedra tilt angles range from 15–17°. In the fourth O2- site, O2- is bonded in a see-saw-like geometry to two equivalent Sr2+ and two equivalent Tl3+ atoms.

Sr₂NdCu₂TlO₇属于正交晶系（orthorhombic）Pmm2空间群，晶体结构为三维骨架。Sr²+以九配位几何构型与九个O²-原子成键，Sr-O键长分布范围为2.53~2.87埃（Å）。Nd³+以体心立方几何构型与八个O²-原子成键，其Nd-O键长包含6个2.48埃的较短键长与2个2.49埃的较长键长。Cu²+与五个O²-原子成键，形成共享顶点的CuO₅四方锥结构，Cu-O键长分布范围为1.94~2.27埃。Tl³+以畸变跷跷板型（see-saw-like）几何构型与四个O²-原子成键，其Tl-O键长包含2个2.13埃的较短键长与2个2.44埃的较长键长。体系中存在4种不等价的O²-占位位点：第一种与第二种O²-占位位点的配位环境完全一致，O²-均以六配位几何构型与2个等价的Sr²+、2个等价的Nd³+以及2个等价的Cu²+原子成键；在第三种O²-占位位点中，O²-与4个等价的Sr²+、1个Cu²+以及1个Tl³+原子成键，形成兼具畸变边共享与顶点共享的OSr₄TlCu八面体（octahedra）结构，此类共享顶点的八面体倾斜角范围为15°~17°；在第四种O²-占位位点中，O²-以跷跷板型几何构型与2个等价的Sr²+以及2个等价的Tl³+原子成键。