USA - USA/China

Russell Hemley and Ho-Kwang Mao

2005 Balzan Prize for Mineral Physics

For the impressive impact of their joint work leading to fundamental breakthroughs, theoretical and experimental, in the field of minerals submitted to extreme physical conditions. They have operated as a highly effective team, characterized by twenty years of research contributions at the highest level. They have developed techniques which allow them to study the behaviour of a wide range of materials, such as hydrogen, the most abundant “mineral” in the universe. Their results have deep implications for our understanding of nature.

Russell Hemley and Ho-Kwang Mao have tackled, for the last twenty years of their joint research, some of the fundamental questions in Mineral Physics. One of them is to understand the behaviour of materials at high pressure. They have developed numerous techniques, including the invention and perfection of synchrotron methods as well as a variety of spectroscopy techniques that have become standards in the field since the 1990s. 

They have extended some of their techniques to examine the most abundant “mineral” in the universe, hydrogen, under conditions of extreme pressure to find new states of hydrogen that have transformed our understanding of this fundamental material.

Calculations on deep Earth mantle phases combined with experiments including the first spectroscopy measurements culminated new models for the Earth’s interior. Specifically, that research has led to results that have changed our views on the deep mantle, especially the core-mantle boundary region. 

Their work has also had an impact on our understanding of the elastic anisotropy and super-rotation of the Earth’s core, the enigmatic trapping of volatiles in the Earth and the existence of novel extraterrestrial minerals. Their research has thus contributed to a better knowledge of the chemistry and physics of the Earth’s mantle and core.

Their results have provided a fundamental basis for the understanding of the interiors of large planets, including those found outside the solar system. Moreover, their work has led to discoveries beyond mineral physics in condensed matter physics, chemistry and materials science. These findings include the existence of novel high-pressure superconductors, superhard materials, new classes of molecular compounds, and high-density amorphous materials.

Because of the deep and broad impact of Hemley-Mao’s work, their leadership in the field and their highly innovative research, they are worthy recipients of the Balzan Prize for Mineral Physics.