Evidence for a High-Pressure Isostructural Transition in Nitrogen

• 作者: Chunmei Fan Shan Liu Jingyi Liu Binbin Wu Qiqi Tang Yu Tao Meifang Pu Feng Zhang Jianfu Li Xiaoli Wang Duanwei He Chunyin Zhou Li Lei
• 来源期刊: 中国物理快报（英文版）
• 年，卷（期）: 2022,（2）
• 所属期刊栏目: CONDENSED MATTER:STRUCTURE,MECHANICAL AND THERMAL PROPERTIES
• 页码范围: 63-75
• 页数: 13页
• 语种: 英文
• DOI: 10.1088/0256-307X/39/2/026401

摘要

We observed an isostructural phase transition in the solid nitrogen λ-N2 at approximately 50 GPa accompanied by anomalies in lattice parameters,atomic volume and Raman vibron modes.The anomalies are ascribed to a slight reorientation of the nitrogen molecules,which does not seem to affect the monoclinic symmetry (space group P21/c).Our ab initio calculations further confirm the phenomena,and suggest an optimized structure for the λ-N2 phase.In addition,a new high-pressure amorphous phase of η'-N2 was also discovered by a detailed investigation of the pressure-temperature phase diagram of nitrogen with the aim of probing the phase stability of λ-N2.Our result may provide helpful information about the crystallographic nature of dissociation transitions in diatomic molecular crystals (H2,O2,N2,etc).