arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 1705.02463cond-mat.mtrl-sci
收藏

X射线驱动下GeO2玻璃的一级相变

X-ray driven first-order phase transition in GeO2 glass under pressure

Xinguo Hong, Matt Newville, Ho-Kwang Mao, T. Irifune, L. Huang

摘要:

前所未有的明亮和强烈的同步辐射X射线已被广泛用于解开许多引人注目的电子和结构性质使用各种各样的物理技术,而令人困惑的现象是测量的不确定性,由于X射线引起相当大的电子和结构变化的物质正在研究。本文利用X射线吸收精细结构(XAFS)和纳米多晶金刚石对顶砧(NPD)装置研究了高压下X射线驱动GeO 2玻璃的一级四面体-八面体相变。在来自波荡器装置的X射线照射下,在低于四面体到五面体转变的阈值压力的5.4GPa下的XAFS谱开始逐渐接近在20.4GPa下的八面体GeO 2的谱。详细的分析表明,GeO 2玻璃在5.4 GPa下的最近距离和配位数增加到20 GPa以上的完全八面体玻璃,而在其他低压下的变化可以忽略不计。这些观察表明,X射线辐照可以作为一种替代刺激,形成致密物质的压力下,众所周知的外部刺激的压力和温度。在外部刺激下形成的致密物质对于理解行星和地球的形成,分化和演化至关重要。注意X射线引起的结构不确定性被称为,特别是在极端条件下,可能成为无法检测的强烈的同步辐射X射线作为结构工具的解决亚稳态。

英文摘要:

Unprecedented bright and intense synchrotron X-rays have been widely used to unravel numerous compelling electronic and structural properties using a large variety of physical techniques, while the puzzling phenomenon is the uncertainties of measurements due to X-ray induced considerable electronic and structural changes of a matter under study. Here, we report an X-ray driven first-order tetrahedral-octahedral phase transition in GeO2 glass at high pressure using X-ray absorption fine structure (XAFS) with a nano-polycrystalline diamond anvil (NPD) cell. Upon X-ray irradiation from an undulator device, the XAFS spectrum at 5.4 GPa, which is below the threshold pressure of tetrahedral to pentahedral transition, starts to progressively approach the spectrum of octahedral GeO2 at 20.4 GPa. Detailed analysis indicates that both the nearest distance and coordination number of GeO2 glass at 5.4 GPa increase to those of a fully octahedral glass above 20 GPa, while negligible changes were found at other low pressures. These observations demonstrate that X-ray irradiation can be served as an alternative stimulus for forming dense matter under pressure, as the well-known external stimuli of pressure and temperature. Dense matter formed under external stimuli is crucial for understanding the formation, differentiation and evolution of planet and Earth. Attention for the X-ray induced structural uncertainties is called, especially for addressing metastable states under extreme conditions which may become undetectable in terms of intense synchrotron X-rays as structural tools.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑