Materials Data on LiFe2OF3 by Materials Project

LiFe2OF3 is Ilmenite-derived structured and crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Li1+ is bonded to one O2- and three F1- atoms to form distorted LiOF3 tetrahedra that share corners with six FeO2F4 octahedra and edges with three FeO2F4 octahedra. The corner-sharing octahedra tilt angles range from 60–65°. The Li–O bond length is 1.86 Å. There is one shorter (1.97 Å) and two longer (2.00 Å) Li–F bond length. There are three inequivalent Fe2+ sites. In the first Fe2+ site, Fe2+ is bonded to two equivalent O2- and four F1- atoms to form FeO2F4 octahedra that share corners with four equivalent FeF6 octahedra, corners with two equivalent LiOF3 tetrahedra, edges with four FeO2F4 octahedra, and edges with two equivalent LiOF3 tetrahedra. The corner-sharing octahedra tilt angles range from 50–52°. Both Fe–O bond lengths are 1.96 Å. There are two shorter (2.30 Å) and two longer (2.36 Å) Fe–F bond lengths. In the second Fe2+ site, Fe2+ is bonded to two equivalent O2- and four equivalent F1- atoms to form FeO2F4 octahedra that share corners with four equivalent FeF6 octahedra, corners with two equivalent LiOF3 tetrahedra, edges with four equivalent FeO2F4 octahedra, and edges with two equivalent LiOF3 tetrahedra. The corner-sharing octahedral tilt angles are 48°. Both Fe–O bond lengths are 2.04 Å. All Fe–F bond lengths are 2.23 Å. In the third Fe2+ site, Fe2+ is bonded to six F1- atoms to form FeF6 octahedra that share corners with twelve FeO2F4 octahedra and corners with six equivalent LiOF3 tetrahedra. The corner-sharing octahedra tilt angles range from 48–52°. There are four shorter (2.15 Å) and two longer (2.16 Å) Fe–F bond lengths. O2- is bonded to one Li1+ and three Fe2+ atoms to form corner-sharing OLiFe3 tetrahedra. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded in a distorted rectangular see-saw-like geometry to one Li1+ and three Fe2+ atoms. In the second F1- site, F1- is bonded in a rectangular see-saw-like geometry to one Li1+ and three Fe2+ atoms.

LiFe₂OF₃为钛铁矿型衍生结构，属单斜晶系C2/m空间群，整体为三维骨架结构。+1价锂离子（Li1+）与1个-2价氧离子（O2-）和3个-1价氟离子（F1-）配位，形成畸变的LiOF₃四面体；该四面体与6个FeO₂F₄八面体共顶点，同时与3个FeO₂F₄八面体共边。共顶点八面体的倾斜角范围为60°~65°，Li—O键长为1.86埃（Å），Li—F键长存在1组较短键长（1.97 Å）与2组长键长（2.00 Å）。体系中存在3个不等价的+2价铁离子（Fe2+）配位位点：在第一个Fe2+位点中，Fe2+与2个等价的O2-及4个F1-配位，形成FeO₂F₄八面体；该八面体与4个等价的FeF₆八面体共顶点、与2个等价的LiOF₃四面体共顶点，同时与4个FeO₂F₄八面体共边、与2个等价的LiOF₃四面体共边，共顶点八面体的倾斜角范围为50°~52°，Fe—O键长均为1.96 Å，Fe—F键长包含2组较短键长（2.30 Å）与2组长键长（2.36 Å）。在第二个Fe2+位点中，Fe2+与2个等价的O2-及4个等价的F1-配位，形成FeO₂F₄八面体；该八面体与4个等价的FeF₆八面体共顶点、与2个等价的LiOF₃四面体共顶点，同时与4个等价的FeO₂F₄八面体共边、与2个等价的LiOF₃四面体共边，共顶点八面体的倾斜角为48°，Fe—O键长均为2.04 Å，所有Fe—F键长均为2.23 Å。在第三个Fe2+位点中，Fe2+与6个F1-配位，形成FeF₆八面体；该八面体与12个FeO₂F₄八面体共顶点，同时与6个等价的LiOF₃四面体共顶点，共顶点八面体的倾斜角范围为48°~52°，Fe—F键长包含4组较短键长（2.15 Å）与2组长键长（2.16 Å）。O2-与1个Li1+及3个Fe2+配位，形成共顶点的OLiFe₃四面体。体系中存在2个不等价的F1-位点：在第一个F1-位点中，F1-以畸变的矩形跷跷板状配位环境与1个Li1+及3个Fe2+配位；在第二个F1-位点中，F1-以矩形跷跷板状配位环境与1个Li1+及3个Fe2+配位。