【摘要】 金刚石压腔是被广泛使用的静高压装置之一，具有压力范围宽，光学适用性优良以及使用便利等优点，对高压科学的发展起到了巨大的推动作用。然而，压力较高时，传压介质固化等因素可能造成压腔内静水压环境失衡，从而产生压力梯度。采用皮秒超声技术测量压腔内各处的声学信号，通过声学数据分析获得了高压下样品腔内硅油的压力分布，结果显示：压力梯度随压强的升高而增大，从1 GPa时的1.3×10^-4 GPa/μm增长为30 GPa时的5.3×10^-2 GPa/μm。该方法不仅克服了以往实验技术在信号测量连续性、样品选择等方面的限制，还可在普通实验室搭建和使用。此外，还结合原位拉曼光谱技术，分析了加压过程中硅油中压力标准差的异常波动，该波动可能与硅油在经历了玻璃化转变之后发生固-固相变有关。更多还原

【Abstract】 Diamond anvil cell（DAC） is a kind of widely used static-high-pressure device. Benefitting from its wide pressure range, excellent optical applicability and convenience of use, DAC provides a tremendous boost to the development of high-pressure science. However, at high pressures, factors like solidification of pressure transmitting medium may cause destruction of the hydrostatic pressure condition in the DAC sample chamber, leading to the generation of pressure gradients. In this work, a new method of using the technique of picosecond ultrasonics to investigate acoustic signal distribution at various locations within the sample chamber was proposed, which can analyze the pressure distribution via the acoustic observations.Limitations in the continuity of signal acquisition, sample selection, etc. can be overcome in this experimental technique, which could be built and manipulated in an ordinary laboratory. Here, pressure gradient in silicon oil was carried out under compression using this technique, and the results revealed that the pressure gradient in the sample chamber increased from 1.3×10^-4 GPa/μm at 1 GPa to 5.3×10^-2 GPa/μm at 30 GPa. In addition,the anomalous change of standard deviation of the pressure distribution was analyzed by combining it with in-situ Raman spectroscopy, then the possible phase transitions of silicone oil at high pressures were discussed.更多还原