Materials Data on Tm2Be2GeO7 by Materials Project

Be2Tm2GeO7 crystallizes in the tetragonal P-42_1m space group. The structure is three-dimensional. Be2+ is bonded to four O2- atoms to form BeO4 tetrahedra that share a cornercorner with one BeO4 tetrahedra and corners with two equivalent GeO4 tetrahedra. There are a spread of Be–O bond distances ranging from 1.57–1.69 Å. Tm3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Tm–O bond distances ranging from 2.22–2.57 Å. Ge4+ is bonded to four equivalent O2- atoms to form GeO4 tetrahedra that share corners with four equivalent BeO4 tetrahedra. All Ge–O bond lengths are 1.76 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted tetrahedral geometry to two equivalent Be2+ and two equivalent Tm3+ atoms. In the second O2- site, O2- is bonded in a 1-coordinate geometry to one Be2+ and three equivalent Tm3+ atoms. In the third O2- site, O2- is bonded in a 2-coordinate geometry to one Be2+, two equivalent Tm3+, and one Ge4+ atom.

Be₂Tm₂GeO₇晶体属于四方晶系P-42₁m空间群。该晶体为三维骨架结构。Be²+与四个O²-离子配位，形成BeO₄四面体；该四面体与一个BeO₄四面体共用一个角顶，同时与两个等价的GeO₄四面体共享角顶。Be—O键的键长分布范围为1.57~1.69 Å。Tm³+采取八配位配位环境，与八个O²-离子配位；Tm—O键的键长分布范围为2.22~2.57 Å。Ge⁴+与四个等价的O²-离子配位，形成GeO₄四面体；该四面体与四个等价的BeO₄四面体共享角顶，所有Ge—O键的键长均为1.76 Å。体系中存在三个不等价的O²-离子位点：在第一个O²-位点中，O²-采取畸变四面体配位环境，与两个等价的Be²+离子和两个等价的Tm³+离子配位；在第二个O²-位点中，O²-采取单配位配位环境，与一个Be²+离子和三个等价的Tm³+离子配位；在第三个O²-位点中，O²-采取双配位配位环境，与一个Be²+离子、两个等价的Tm³+离子以及一个Ge⁴+离子配位。