报告题目：Hydrogen under simultaneous high pressure-temperature conditions

报告人：Chang-Sheng Zha，美国卡耐基研究院 研究员

报告时间：2023年10月30日 10：00

报告地点：伟德BETVlCTOR1946中心校区唐敖庆楼B521会议室

报告简介

　　Hydrogen study under extreme pressure-temperature (PT) conditions has fundamental importance for the development of condensed physics, material and planetary sciences. The prediction of an insulator to metallic state transition at sufficient pressure, which was proposed more than eighty years ago, has been a long-standing open question for the high pressure community. Recently, more experimental and theoretical interests were focused on the hot-dense state of hydrogen. Experiments for these studies are mostly conducted in shock compression or pulsed laser heating which resulted in controversy observations. Phase diagram above 300 K to the melting line still remained almost as a virgin territory.

　　Hydrogen study also has been one of the engines driving the advance of static pressure-temperature technologies. New developments in hydrogen study have brought pressure generation and signal probing techniques into over 300 GPa and 900 K range, leading to more new phases found. The experimental results, reported in this talk using new static pressure-temperature DAC techniques, demonstrate that hydrogen has much more complicated phase behaviors at this PT range than it can be expected previously.

报告人简介

　　Chang-Sheng Zha develops and uses a variety of experimental techniques in the study of high P-T physics, chemistry, geosciences and material science. His contributions in high pressure elasticity measurements of the Earth-forming materials using Brillouin scattering spectroscopy and synchrotron x-ray diffraction led to a better understanding of the layered structures of the Earth’s deep interior. Same technique leads to creating a primary pressure scale based on simultaneous elasticity and density measurements that can be used for verifying the validity of all pressure standards. Zha has also been developing the resistive heating techniques in combination with modern diamond anvil cell technique for many years. His newly improved internal resistive heating technique has been a successful tool for studies of phase transitions, equations of state, and material synthesis at simultaneous pressure-temperature conditions of the lower mantle.

　　His recent studies of hydrogen, helium, and water ice at extreme pressure-temperatures are of importance for the Earth-planetary sciences. The achievements for hydrogen study using optical, Raman, and infrared spectroscopy in 300 – 400 GPa and large temperature range are among the world's most challenging high P-T explorations for this very important element.

He was a professor (associate) in USTC; staff scientist (in charge of the high pressure program) at Cornell High Energy Synchrotron Source, Cornell University; and research scientist at Carnegie Institution for Science.

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