讲座时间：2024年6月13日 15：00-17：00
讲座地点：地质楼204会议室
主持人：吴嘉 副教授
专家介绍：周义明，中国科学院深海科学与工程研究所特聘研究员。他于1945年出生于台湾，并在1968年获得台湾大学地质学学士学位，后于1974年取得美国约翰霍普金斯大学地球与行星科学系地球化学博士学位，并在原校及NASA各当两年博后。在1979年到2013年的34年间，他工作于美国内政部地质调查局（USGS），并于2013年入职中国科学院深海科学与工程研究所，创建深海极端环境模拟研究实验室。周义明研究的研究范围主要涵盖实验地球化学的技术开发，地质流体、矿物及气体水合物（包括天然气水合物）在不同条件下的物理化学性质。他在Science、PANAS、Geology、EPSL、GPL、GCA等国际知名期刊上发表了200余篇论文，论文总引数超过8000次。
讲座内容：Dr. Zhou’s talk focus on how to control and measure Redox in hydrothermal experiments. In addition to pressure (P) and temperature (T), oxygen fugacity is another important extensive parameter in hydrothermal experiments simulating natural geological processes, especially for those related to the stabilities of minerals and metal-chloride complexes in aqueous fluids containing multivalence elements. The oxygen buffer and Shaw membrane techniques have been widely used in these experiments, but they can only be applied for experiments above 500ºC, because at lower T’s the permeability of hydrogen through the osmotic membrane of H2 commonly used in these experiments (e.g., Pt or Ag-Pd alloys) is quite low, and therefore, equilibrium control of the redox state of the sample cannot be reached in a reasonable experimental duration (weeks or month). Fortunately, their ability to control the redox state of hydrothermal experiments at lower temperatures became possible, when fused silica was used as the osmotic membrane of H2. Furthermore, the exact redox state of an experimental system can be checked by using the hydrogen fugacity sensor, in the form of either Pt capsule or fused silica capillary capsule, at temperatures above or below 500ºC, respectively. Also, it is now possible to determine the redox state of a sample in an optical cell, with either diamond or fused silica window, at elevated P-T conditions by using in situ quantitative Raman spectroscopic analysis method.
