限域条件下氮分子的高温高压诱导聚合  

High-pressure high-temperature induced polymerization of nitrogen molecules under restricted condition

作　　者：郭琳琳 赵梓彤 隋明宏 王鹏[1] 刘冰冰[1] Guo Lin-Lin;Zhao Zi-Tong;Sui Ming-Hong;Wang Peng;Liu Bing-Bing(State Key Laboratory of Superhard Materials,Jilin University,Changchun 130012,China)

机构地区：[1]吉林大学,超硬材料国家重点实验室,长春130012

出　　处：《物理学报》2024年第8期237-243,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:12174143)资助的课题.

摘　　要：聚合氮被认为是一种极具潜力的新型高能量密度材料,但是高温高压条件下合成的聚合氮结构往往具有较低热力学稳定性.限域策略有助于聚合氮高压结构的稳定,为氮聚合提供了新的调控途径.本文在氮化硼纳米管中限域分子氮,利用高压原位拉曼散射光谱表征技术研究不同含氮量限域体系的高压诱导氮聚合及聚合氮结构的卸压稳定性.研究表明,在高含氮量的体系中,限域到氮化硼纳米管内的N_(2)与非限域的N_(2)的拉曼特征振动峰表现出不同的拉曼光谱压力响应行为.在123 GPa压力下,利用激光加热诱导氮分子间聚合,生成cg-N聚合氮结构.卸压过程中,未被限域的cg-N在40 GPa左右发生爆炸性分解,分解产生的能量影响了限域cg-N的稳定性,使其同样发生分解.环境压力下限域N_(2)可能以液态形式稳定存在.在低含氮量限域体系中,高温高压下限域N2结晶生成了含有N=N双键的晶体结构,其中的N=N双键有两种长度,分别接近N_(3)阴离子及N_(4)^(+)团簇中N=N双键的键长.在卸压过程中这种结构可以稳定至25 GPa.Polymeric nitrogen has been recognized to be a new type of high-energy density material(HEDM).However,the polymeric nitrogen structure formed under high-pressure and high-temperature conditions is usually is poor thermodynamic stability.Confinement strategy is conductive to the stabilization of the highpressure phase of polymeric nitrogen structures,providing a new modulation approach for realizing the polymerization of nitrogen.In this work,nitrogen molecules are confined into the boron nitride nanotubes(N2@BNNTs)under high-pressure condition.The pressure-induced polymerization of nitrogen in N_(2)@BNNT samples with varying nitrogen content and the stabilities of polymeric nitrogen structure are characterized by high-pressure in situ Raman spectroscopy method.In the N_(2)@BNNT sample with higher nitrogen content,the N_(2) confined to boron nitride nanotubes exhibits different Raman spectral pressure response behaviors compared with that of non confined N_(2),but both of them are transformed into cg-N structure after laser heating at about123 GPa.With pressure decreasing to 40 GPa,the unconfined cg-N decomposes and releases huge energy,which affects the stability and results in the decomposition of the confined cg-N.Under ambient conditions,the confined N_(2) is stabilized in the liquid phase.In the N_(2)@BNNTs sample with lower nitrogen content,the confined N_(2) is transformed into new polymeric nitrogen structure,which possesses N=N double bonds with different bond lengths close to the those in the N_(3)^(-)anion and N_4^(+)clusters,respectively,after laser-heating is the pressure range of 122-150 GPa.This poly nitrogen structure is stable with pressure decreasing to 25 GPa.This work provides new insights into the synthesis and stabilization of polymeric nitrogen structures,opening up new avenues for developing these advanced structures.

关 键 词：限域 聚合氮 高温高压 

分 类 号：TQ560.1[化学工程—炸药化工]