钙钛矿结构氧氮化物SrTaO_(2)N的高温高压结构稳定性研究  

Structural stability of the perovskite-structured oxynitride SrTaO_(2)N under high-pressure and high-temperature conditions

作　　者：罗兴丽 谭大勇[1,5] 陈炜珊 李端 曾良 肖万生 LUO Xingli;TAN Dayong;CHEN Weishan;LI Duan;ZENG Liang;XIAO Wansheng(CAS Key Laboratory of Mineralogy and Metallogeny,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;Key Lab of Guangdong Province for Mineral Physics and Materials,Guangzhou 510640,Guangdong,China;CAS Center for Excellence in Deep Earth Science,Guangzhou 510640,Guangdong,China;University of Chinese Academy of Sciences,Beijing 100049,China;Institute of Advanced Science Facilities,Shenzhen 518107,Guangdong,China;Science and Technology on Advanced Ceramic Fibers and Composites Laboratory,College of Aerospace Science and Engineering,National University of Defense Technology,Changsha 410073,Hunan,China)

机构地区：[1]中国科学院广州地球化学研究所矿物学与成矿学重点实验室,广东广州510640 [2]广东省矿物物理与材料研究开发重点实验室,广东广州510640 [3]中国科学院深地科学卓越创新中心,广东广州510640 [4]中国科学院大学,北京100049 [5]深圳综合粒子设施研究院,广东深圳518107 [6]国防科技大学空天科学学院新型陶瓷纤维及其复合材料重点实验室,湖南长沙410073

出　　处：《地球化学》2024年第3期445-453,共9页Geochimica

基　　金：国家自然科学基金项目(41372047、42172046);中国科学院战略性先导科技专项(B类)(XDB18010403)联合资助。

摘　　要：N2是地球大气的主要组分,N元素是生命起源的基础元素,了解N在地球深部高温高压环境中的赋存形式是探讨全球N循环和宜居性地球大气环境的重要基础。本研究应用金刚石对顶砧(DAC)高压装置和激光加温技术模拟地球深部的压力和温度环境,通过高压原位同步辐射X射线衍射和拉曼光谱对钙钛矿结构氧氮化物SrTaO_(2)N开展高温高压结构稳定性研究。高压X射线衍射结果表明,在0~40.5 GPa的压力范围内,四方结构SrTaO_(2)N没有发生相变,其体积模量为K_(0)=290(3) GPa,并具有a轴和c轴的压缩各向异性。压缩过程中,Ta(O,N)_(6)八面体主要发生刚性旋转,旋转角为0.25°~12.64°,但保持四方结构稳定。常温高压(300 K,40.2 GPa)与高温高压(1800±200 K,41.3 GPa)拉曼对比实验结果显示,在高温高压条件下,SrTaO_(2)N仍保持初始的拉曼谱特征,结构稳定。本研究结果揭示,常压高温条件下通过N^(3-)替代O^(2-)合成的钙钛矿结构氧氮化物,能够在地球内部下地幔上部的温压环境下稳定存在。这种以钙钛矿结构存在的氧氮化物可能是地球深部隐藏的N储库,为解释地球N亏损现象提供了重要线索,同时也为探索N在地球深部中的赋存及其对全球N循环和宜居性大气环境的影响提供了新的研究方向。Nitrogen is the main component of the earth’s atmosphere,and it is an essential element of the origin of life.Understanding the occurrence of nitrogen reservoirs in the deep earth is an important and fundamental issue for exploring the global nitrogen cycle and the evolution of habitable atmosphere environment.In this study,the temperature and pressure of the deep mantle was simulated using a heating diamond anvil cell(HDAC),and the stability of perovskite-structured oxynitride SrTaO_(2)N at high pressure and high temperature was investigated using in situ high-pressure synchrotron X-ray diffraction and Raman scattering.The result of high-pressure X-ray diffraction shows that at the room temperature and high pressure condition(0–40.5 GPa),the tetragonal structured SrTaO_(2)N exhibits anisotropic compressibility of the a-axis and c-axis with a compression modulus K_(0)=290(3)GPa,and no structural phase transition was observed.During compression,the adjacent Ta(O,N)_(6) octahedra are rotated from 0.25°to 12.64°,maintaining a stable tetragonal structure.Raman spectra at room temperature and high pressure show that SrTaO_(2)N retains tetragonal perovskite structure at room temperature and high pressure(300 K,40.2 GPa)and at high temperature and high pressure(1800±200 K,41.3 GPa).Our results reveal that perovskite-structured oxynitride can be maintained in the temperature and pressure environment of the upper part of the lower mantle,which indicates that the perovskite=structured oxynitride may be a hidden nitrogen reservoir in the deep earth.Therefore,this study not only provides an important clue to explain the“missing”nitrogen in the earth but also sheds light on research concerning the occurrence of nitrogen in the deep earth and the influence of deep nitrogen on the global nitrogen cycle and habitable atmosphere environment.

关 键 词：N储库 SrTaO_(2)N 高温高压 X射线衍射 拉曼光谱 

分 类 号：P579[天文地球—矿物学]