Ho-kwang (Dave) Mao

Ho-kwang (Dave) Mao joins his principal collaborator and fellow Staff Member, Russell Hemley, in the belief that high-pressure research is reaching a turning point and may soon emerge as a dominant branch of modern science. Mao is a pioneer in ultrahigh-pressure technology. He has repeatedly demonstrated how innovative high-pressure experimentation has exposed new scientific phenomena critical to solving problems in physics and the planetary sciences. As the field grows, he foresees that it will also add new dimensions to research in chemistry, the material sciences, and technology.

Mao is a principal investigator at the Center for High Pressure Research (CHiPR) and director of the newly established high-pressure collaborative access team at the Advanced Photon Source at Argonne National Laboratory. Mao is an expert on research using multimegabar techniques, especially with the diamond-anvil cell. He and former colleague Peter Bell first reached 1 megabar static pressure in 1976, an advancement that doubled the previous pressure limit. Three years later, Mao and Bell became the first to compress hydrogen to solid form at room temperature. Mao and his colleagues have been steadily improving the multimegabar technique ever since, integrating it with methods of analysis such as synchrotron x-ray diffraction and infrared, Raman, and other kinds of spectroscopies. By 1990, the high-pressure researchers reached 1.8 megabars and detected evidence of a transition to metallic hydrogen in the molecular form.

Mao and his collaborators have made a myriad of discoveries about physical and chemical phenomena at high pressures, including pressure-induced amorphization and crystallization and electronic and structural phase transitions, as well as discoveries relevant to planetary interiors. Several years ago, for example, Mao participated in an investigation of the core of Mars. With his colleagues, including Charles Prewitt and Yingwei Fei, he suggested that sulfur might be a possible light-element component of the Martian core. The year before, Mao and Fei raised the possibility that sulfur and oxygen could both be components of the Earth's largely iron core.