Scelta Demetrio, Dziubek Kamil F, Ende Martin, Miletich Ronald, Mezouar Mohamed, Garbarino Gaston, Bini Roberto
ICCOM-CNR, Institute of Chemistry of OrganoMetallic Compounds, National Research Council of Italy, Via Madonna del Piano 10, I-50019 Sesto Fiorentino, Firenze, Italy and LENS, European Laboratory for Non-linear Spectroscopy, Via N. Carrara 1, I-50019 Sesto Fiorentino, Firenze, Italy.
LENS, European Laboratory for Non-linear Spectroscopy, Via N. Carrara 1, I-50019 Sesto Fiorentino, Firenze, Italy.
Phys Rev Lett. 2021 Feb 12;126(6):065701. doi: 10.1103/PhysRevLett.126.065701.
We present a study on the phase stability of dense carbon dioxide (CO_{2}) at extreme pressure-temperature conditions, up to 6200 K within the pressure range 37±9 to 106±17 GPa. The investigations of high-pressure high-temperature in situ x-ray diffraction patterns recorded from laser-heated CO_{2}, as densified in diamond-anvil cells, consistently reproduced the exclusive formation of polymeric tetragonal CO_{2}-V at any condition achieved in repetitive laser-heating cycles. Using well-considered experimental arrangements, which prevent reactions with metal components of the pressure cells, annealing through laser heating was extended individually up to approximately 40 min per cycle in order to keep track of upcoming instabilities and changes with time. The results clearly exclude any decomposition of CO_{2}-V into the elements as previously suggested. Alterations of the Bragg peak distribution on Debye-Scherrer rings indicate grain coarsening at temperatures >4000 K, giving a glimpse of the possible extension of the stability of the polymeric solid phase.
我们展示了一项关于致密二氧化碳（CO₂）在极端压力 - 温度条件下相稳定性的研究，压力范围为37±9至106±17 GPa，温度高达6200 K。对在金刚石对顶砧细胞中致密化的激光加热CO₂记录的高压高温原位X射线衍射图谱进行研究，在重复激光加热循环所达到的任何条件下，均一致再现了聚合四方CO₂ - V的唯一形成。通过精心设计的实验装置（可防止与压力细胞的金属成分发生反应），每个循环通过激光加热进行的退火时间可单独延长至约40分钟，以便跟踪即将出现的不稳定性和随时间的变化。结果明确排除了如先前所建议的CO₂ - V分解为元素的情况。德拜 - 谢乐环上布拉格峰分布的变化表明在温度>4000 K时晶粒粗化，这让我们得以瞥见聚合固相稳定性可能的扩展情况。
