标题：Theoretical insight into the structural stability of KZnB _3O _6 polymorphs with different BO _x polyhedral networks
作者：Yang, L.;Fan, W.;Li, Y.;Sun, H.;Wei, L.;Cheng, X.;Zhao, X.
作者机构：[Yang, L] State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China;[ Fan, W] School of Chemistry and Chemical Engineering, 更多
通讯作者地址：[Fan, WL]Shandong Univ, Sch Chem & Chem Engn, Jinan 250100, Peoples R China.
来源：Inorganic Chemistry: A Research Journal that Includes Bioinorganic, Catalytic, Organometallic, Solid-State, and Synthetic Chemistry and Reaction Dynamics
摘要：In general, the presence of shared edges of polyhedra for high-valence low-coordinated small cations is rarely seen except under extreme conditions such as high pressure. However, the ambient-pressure synthesis of KZnB _3O _6 built of edge-sharing BO _4 tetrahedra is contrary to this. By investigating the molecular dynamics, lattice dynamics, and electronic properties via density functional theory, we studied the origin of the phase stability of the edge-sharing (es) and \"corner-sharing (cs)\" KZnB _3O _6. Lattice dynamics results show that there are no phonon anomalies that could lead to the instability of es-KZnB _3O _6, which is consistent with molecular dynamics analysis. For \"cs-KZnB _3O _6\", a soft mode at the G point in the phonon dispersion is identified that reflects the dynamic instability with respect to small distortions. Eigenvector analysis of the soft mode of \"cs-KZnB _3O _6\" indicates that the instability comes from the linkage of ZnO _5 polyhedra rather than BO _x polyhedra. Electronic property calculation indicates that the edge-sharing BO _4 polyhedra connected by the longest B-O σ bonds provide a solid framework for es-KZnB _3O _6. In the case of \"cs-KZnB _3O _6\", the overlong Zn-O bond possesses the smallest covalent nature and the least orbital overlap among the bonds in a ZnO _5 polyhedron, and these two features of the electronic structure reduce the stability of \"cs-KZnB _3O _6\" compared to es-KZnB _3O _6. The electronic property calculation further confirms the results obtained from lattice dynamics analysis.