Ho-Kwang (Dave) Mao (Chinese: 毛河光; pinyin: Máo Héguāng; Wade–Giles: Mao Ho-kuang; born June 18, 1941) is a Chinese-American geologist. He is the director of the Center for High Pressure Science and Technology Advanced Research in Shanghai, China.[2] He was a staff scientist at Geophysical Laboratory of the Carnegie Institution for Science[3] for more than 30 years. Mao is a recognized leading scientist in high pressure geosciences and physical science. There are two minerals named after him, Davemaoite and Maohokite.
From 1968 to 1972, Mao did his postdoctoral research at the Geophysical Laboratory of the Carnegie Institution of Washington (CIW). From then on Mao has spent his career at Geophysical Laboratory as a Senior Staff scientist.
In 2013, Mao founded Center for High Pressure Science and Technology Advanced Research in his birthplace, Shanghai.[2][6] He takes the director role at the center and leads a group of international scientists to tackle world-class scientific challenges.[6] The center has a Nature index of 17.68 in 2021 and was on an increasing trend since 2016.[7]
Mao has three daughters - Cyndy, Linda, and Wendy. His youngest daughter, Wendy Mao, is a professor of geological sciences at Stanford University.[8]
Research
Achieving high pressure and pressure calibration methods
Mao is one of the most prolific users of the diamond anvil cell for research at high pressures. Although at the time the claim was controversial,[9] his work with Peter M. Bell is now generally accepted as being the first verified static pressure in excess of 1 Megabar.[10][11]
Mao and colleagues first calibrated ruby fluorescence pressure scale to 80 GPa and this method has been widely used in almost every diamond anvil cell experiments.[12] This work has been cited by 3921 times as of Jan 15, 2022, according to google scholar.
In 2018, 400 GPa was achieved by his team and a detailed description of pressure loading and distribution, gasket thickness variation, and diamond anvil deformation was reported.[13][14]
Towards metallic hydrogen
Mao is a pioneer in experimentally exploring the possible metallic hydrogen phase under high pressure. His work on solid hydrogen starts in 1988, where he reported single-crystal structure of hydrogen up to 26.5 GPa.[15] He later published a review paper on transitions in solid hydrogen in 1994.[16] In 1996, his team's work[17] suggested a more compressible solid hydrogen than previously thought. More recently in 2019, his team published results on single crystal diffraction of the lightest material in the world, hydrogen, up to 254 GPa and revealed isostructural electronic transitions in solid hydrogen at around 220 GPa.[18]
Mao discovered formation of FeO2Hx from goethite FeOOH[20] or from iron-water reaction[21] under Earth's lower mantle conditions. The novel FeO2Hx phase processes a pyrite structure. Since this phase can contain varied amount of hydrogen,[22] it would have important implications for the deep water cycle.[23][24]
In 2021, davemaoite, a mineral found only in the deep mantle of the earth, was named after Mao. It is estimated to make 5–7% of the Earth's lower mantle.[3]
^Prewitt, C. T. (1 May 2006). "Presentation of the Roebling Medal for 2005 of the Mineralogical Society of America to Ho-kwang Mao". American Mineralogist. 91 (5–6): 965–966. Bibcode:2006AmMin..91..965P. doi:10.2138/am.2006.459.
^Mao, H.-k. D. (1 May 2006). "Acceptance of the Mineralogical Society of America Roebling Medal for 2005". American Mineralogist. 91 (5–6): 967–968. Bibcode:2006AmMin..91..967M. doi:10.2138/am.2006.460.
