Materials Data on K2Cd3Se4 by Materials Project

K2Cd3Se4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to six Se2- atoms to form distorted KSe6 octahedra that share corners with ten CdSe4 tetrahedra, edges with six KSe6 octahedra, and edges with four CdSe4 tetrahedra. There are a spread of K–Se bond distances ranging from 3.35–3.57 Å. In the second K1+ site, K1+ is bonded to six Se2- atoms to form distorted KSe6 octahedra that share corners with twelve CdSe4 tetrahedra, edges with six KSe6 octahedra, and edges with three CdSe4 tetrahedra. There are a spread of K–Se bond distances ranging from 3.47–3.58 Å. There are two inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded to four Se2- atoms to form CdSe4 tetrahedra that share corners with six KSe6 octahedra, corners with four equivalent CdSe4 tetrahedra, edges with three KSe6 octahedra, and edges with two equivalent CdSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 13–95°. There are a spread of Cd–Se bond distances ranging from 2.64–2.79 Å. In the second Cd2+ site, Cd2+ is bonded to four Se2- atoms to form CdSe4 tetrahedra that share corners with eight KSe6 octahedra, corners with four CdSe4 tetrahedra, edges with two KSe6 octahedra, and edges with two CdSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 10–95°. There are a spread of Cd–Se bond distances ranging from 2.65–2.81 Å. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 6-coordinate geometry to three K1+ and three Cd2+ atoms. In the second Se2- site, Se2- is bonded in a 6-coordinate geometry to three K1+ and three Cd2+ atoms. In the third Se2- site, Se2- is bonded to three K1+ and three Cd2+ atoms to form a mixture of distorted edge and corner-sharing SeK3Cd3 octahedra. The corner-sharing octahedra tilt angles range from 0–55°.

K₂Cd₃Se₄（K2Cd3Se4）结晶于正交晶系（Orthorhombic）Pnma空间群（space group）。该晶体为三维结构。体系中存在两个不等价的K⁺（K1+）配位位点。在第一个K⁺配位位点中，K⁺与6个Se²⁻（Se2-）原子成键，形成畸变的KSe₆八面体；该八面体与10个CdSe₄四面体共享顶点，与6个KSe₆八面体共享棱，同时与4个CdSe₄四面体共享棱。K-Se键的键长分布范围为3.35~3.57 Å。在第二个K⁺配位位点中，K⁺与6个Se²⁻原子成键，形成畸变的KSe₆八面体；该八面体与12个CdSe₄四面体共享顶点，与6个KSe₆八面体共享棱，同时与3个CdSe₄四面体共享棱。K-Se键的键长分布范围为3.47~3.58 Å。体系中存在两个不等价的Cd²⁺（Cd2+）配位位点。在第一个Cd²⁺配位位点中，Cd²⁺与4个Se²⁻原子成键，形成CdSe₄四面体；该四面体与6个KSe₆八面体共享顶点，与4个等价的CdSe₄四面体共享顶点，同时与3个KSe₆八面体共享棱，与2个等价的CdSe₄四面体共享棱。共顶八面体的倾斜角分布范围为13°~95°。Cd-Se键的键长分布范围为2.64~2.79 Å。在第二个Cd²⁺配位位点中，Cd²⁺与4个Se²⁻原子成键，形成CdSe₄四面体；该四面体与8个KSe₆八面体共享顶点，与4个CdSe₄四面体共享顶点，同时与2个KSe₆八面体共享棱，与2个CdSe₄四面体共享棱。共顶八面体的倾斜角分布范围为10°~95°。Cd-Se键的键长分布范围为2.65~2.81 Å。体系中存在三个不等价的Se²⁻（Se2-）配位位点。在第一个Se²⁻配位位点中，Se²⁻以6配位构型与3个K⁺和3个Cd²⁺原子成键。在第二个Se²⁻配位位点中，Se²⁻以6配位构型与3个K⁺和3个Cd²⁺原子成键。在第三个Se²⁻配位位点中，Se²⁻与3个K⁺和3个Cd²⁺原子成键，形成畸变棱共享与顶点共享共存的SeK₃Cd₃八面体。共顶八面体的倾斜角分布范围为0°~55°。