具有全sp^(2)杂化聚合氮层超氮化合物的高压合成研究

High-pressure synthesis of fully sp^(2)-hybridized polymeric nitrogen layer in potassium supernitride

类石墨烯全sp^(2)杂化二维结构具有承载非平庸的拓扑电子结构的能力.本文利用激光加热对顶砧技术,在高温高压条件下首次获得全sp^(2)杂化类石墨烯二维聚合氮结构.全sp^(2)杂化的聚合氮层由环状N18单元组成,与钾原子层构成了类三明治结构的K_(2)N_(16)超氮材料.K_(2)N_(16)能带结构呈现拓扑半金属特性,是新型的高阶色散狄拉克费米子材料.全sp^(2)杂化的聚合氮的合成研究为探索新型拓扑材料提供了新的高压策略.

Searching for fully sp^(2)-hybridized layered structures is of fundamental importance because of their fascinating physical properties and potential to host topologically non-trivial electro nic states.However,the synthesis of fully sp^(2)-hybridized layered polymeric nitrogen structures remains a challenging work because of their low stability.Here,we report the synthesis of a fully sp^(2)-hybridized layered polymeric nitrogen structure featuring fused 18-membered rings in potassium supernitride(K_(2)N_(16))under high-pressure and high-temperature conditions.Bader charge analysis reveals that the potassium atomic layer stabilizes the unique sp^(2)-hybridized polymeric nitrogen layers through the charge transfer effect in K_(2)N_(16).The calculation of electronic structure indicates that K_(2)N_(16)is a topological semimetal with multiple Dirac points and hosts higher-order Dirac fermions with cubic dispersion,which are contributed by the sp^(2)-hybridized polymeric nitrogen layers arranged in P6/mcc symmetry.The high-pressure synthesis of the fully sp^(2)-hybridized polymeric nitrogen layered structure provides promising prospects for exploring novel topological materials with effective stabilization routes.