活塞圆筒和多面砧高压装置中常用的氧逸度控制和原位监测方法

Control and monitor of oxygen fugacity in piston-cylinder and multi-anvil apparatus

氧逸度是定量表示一个体系氧化还原能力的指标,反映了体系中氧气的分压或者逃逸能力。在地球科学中,它反映了岩石和矿物中变价元素的氧化还原状态,指示了不同岩石矿物氧化性/还原性的相对强弱。相同岩石矿物不同氧逸度可以导致其物理化学性质发生大的改变,因此在实验地球科学中准确控制并监测高温高压实验条件下的氧逸度具有非常重要的意义。本文从实验技术角度出发,首先介绍了活塞圆筒和多面砧高压装置中利用双胶囊技术在不含水和含水体系中控制氧逸度的方法、原理、装置和注意事项;接着描述了用过渡金属合金固溶体和惰性金属合金作为氧传感器原位测量氧逸度的原理、注意事项和地质应用,然后展示了氧离子固体电解质法控制和监测氧逸度的原理、装置和局限,提出了可能的改进方法。目前由于技术限制,氧逸度在高压实验中的控制和监测方法还不成熟,导致其对矿物和岩石物理化学性质的影响极可能被低估甚至错估。因此积极研究发展并推动高压下氧逸度的控制和监测技术非常重要且必要。

Oxygen fugacity quantifies the oxidizing and reducing capacity of a system,also reflects the oxygen partial pressure or escape ability.In geoscience,it is related with the valence state of redox-sensitive elements of rocks and minerals,and indicates their relative oxidability and reducibility.Rocks and minerals with the same composition under different oxygen fugacities might show contrastingly different physical and chemical properties.Therefore,it is of vital importance to accurately control and monitor oxygen fugacity in high-pressure and high-temperature experiments.This paper focuses on how to control and monitor oxygen fugacity in piston-cylinder and multi-anvil apparatus technically.First,the doublecapsule technique,its principle,set-up configurations and experimental tips under hydrous and anhydrous systems which is well developed for controlling oxygen fugacity is introduced.Then redox sensor method including transition metal-solid solution and inert metal-solid solution which is used for monitoring oxygen fugacity is demonstrated next.Finally,the principle and set-up of oxygen solid electrolyte sensor method is exhibited,with some possible improvement raised up.Due to technical limitation,in-situ oxygen fugacity control and monitor in high-pressure apparatus are far from well-developed,which results in underestimation or even erroneous estimation of the influence of oxygen fugacity on physical and chemical properties of rocks and minerals.Therefore,development in control and monitor of oxygen fugacity in high-pressure apparatus is of great urgent and significance.