基于拉曼频移的白宝石压腔无压标系统高温高压实验标定

在高压实验科学中, 各类宝石压腔是最为常见的高压设备之一, 其样品腔中压力的精确标定是实验的关键. 目前, 人们主要通过加入红宝石等压标物质来进行定压, 但压标物质的加入会增加实验的装样难度, 改变样品腔中的物理化学环境, 甚至直接与实验样品发生反应, 从而对实验结果产生影响. 在0–6.3 GPa和300–573 K下, 利用共聚焦拉曼显微镜, 根据白宝石压砧砧面的ν₁₂ 拉曼频移与温度和压力的变化关系, 建立了一套适用于高温高压水热体系的无压标白宝石压腔系统. 实验结果表明: 白宝石砧面的ν₁₂ 峰随着压力的升高发生线性蓝移, 而随着温度升高则发生线性红移, 且温度和压力对拉曼频移的影响存在耦合效应. 利用本实验结果, 可在高温高压下根据白宝石砧面的拉曼频移计算出样品腔的压力P=(Δλ-0.01913×ΔT)/(1.9158-0.00105×ΔT), 在物理学、材料学和地球科学等领域具有重要应用.

Raman spectra based pressure calibration of the non-gauge sapphire anvil cell at high temperature and high pressure

Gem anvil cell is on important tool in high pressure experimental research, and the key of its application is the accurate calibration of the pressure in sample chamber. To date, the pressure has been routinely calibrated by the extra gauge such as ruby. This may increase the difficulty in building a setup and changing the chemical environment, even chemical reaction happens with the sample, thereby degrading the experimental results. In this study, using the synthesized pale sapphire and the heatable Zha-Bassett type cell, the relationships between Raman shift of sapphire-anvil interface and the pressure, and also temperature in chamber are investigated by the confocal Raman microscope at 0-6.3 GPa and 300-573 K, which is used to establish a non-gauge sapphire anvil cell system. The result shows that the pressure induced Raman shift of sapphire anvil at room temperature is 1.6443 cm^-1/GPa and the temperature induced shift at room pressure is -0.0198 cm^-1/K. We fit the experimental data at simultaneous high temperature and high pressure (HTHP) and find that: ∂ν₁₂/∂T=-0.01913-0.00105×P, ∂ν₁₂/∂P=1.9158-0.00105×T. The effect between the pressure and temperature can be described by ∂ν₁₂/∂P∂T=-0.00105. After this calibration: P=(Δλ-0.01913×ΔT)/(1.9158-0.00105×ΔT), the pressure in the sample chamber can be calculated by the Raman shift of the interface of anvil cell in the HTHP experiment, which can be directly used in hydro-thermal reaction system and has great importance in physics, material science and geoscience.