Our ability to determine the density (specific volume) as a function of pressure and temperature has drastically improved in the last several decades, with the combination of synchrotron X-ray diffraction and high-pressure techniques such as laser-heated diamond-anvil cell and large-volume multi-anvil press. The improvements are in both pressure–temperature range and data quality, and obtaining high-resolution 2D angle-dispersive diffraction data at over a megabar pressure and above 2,500 K is now routine. In parallel, dynamic compression techniques, such as laser-driven shock wave and magnetically accelerated flyer plate-impact experiments, have provided new ways to measure density at extreme conditions. The combination of static and dynamic compression data allows us to examine internal consistency in pressure determination and establish reliable pressure scales. Internally consistent pressure scales for several pressure standards are emerging through extensive comparison of compression data over a large pressure range and simultaneous measurements of elasticity and density. A concerted effort is needed to further expand and improve measurements under simultaneous high pressure and temperature, particularly at temperatures above 2,500 K, in order to accurately model the thermal pressure. To decipher the compositions of the Earth’s interior based on density observations from seismology requires high accuracy in measuring the subtle compositional effects on the density of mantle and core materials. For a universal understanding of the thermal equations of state of solids, the emphasis should be on reconciling the static and dynamic data of well-studied materials that have substantial overlap in pressure–temperature ranges.

In October of 2018, a group of scientists gathered at the Broad Branch Road campus of the Carnegie Institution for Science to celebrate 50 years of high-pressure research by Ho-Kwang “Dave” Mao at the Geophysical Laboratory. The celebration highlighted the growth of high-pressure mineral physics over the last half century, which has matured into a vibrant discipline in the physical sciences because of its intimate connections to Earth and planetary sciences, solid-state physics, and materials science. Dave’s impact in high-pressure research for over a half a century has been immense, with a history of innovation and discovery spanning from the Earth and planetary sciences to fundamental materials physics. Dave has always been an intrepid pioneer in high-pressure science, and together with his numerous colleagues and collaborators across the world he has driven the field to ever higher pressures and temperatures, guided the community in adopting and adapting a spectrum of new technologies for in situ interrogation of samples at extreme conditions, and relentlessly explored the materials that make up the deep interiors of planets. In this volume, we assemble 15 chapters from authors who have worked with, been inspired by, or mentored by Dave over his amazing career, spanning a range of subjects that covers the entire field of high-pressure mineral physics.

In October of 2018, a group of scientists gathered at the Broad Branch Road campus of the Carnegie Institution for Science to celebrate 50 years of high-pressure research by Ho-Kwang “Dave” Mao at the Geophysical Laboratory. The celebration highlighted the growth of high-pressure mineral physics over the last half century, which has matured into a vibrant discipline in the physical sciences because of its intimate connections to Earth and planetary sciences, solid-state physics, and materials science. Dave’s impact in high-pressure research for over a half a century has been immense, with a history of innovation and discovery spanning from the Earth and planetary sciences to fundamental materials physics. Dave has always been an intrepid pioneer in high-pressure science, and together with his numerous colleagues and collaborators across the world he has driven the field to ever higher pressures and temperatures, guided the community in adopting and adapting a spectrum of new technologies for in situ interrogation of samples at extreme conditions, and relentlessly explored the materials that make up the deep interiors of planets. In this volume, we assemble 15 chapters from authors who have worked with, been inspired by, or mentored by Dave over his amazing career, spanning a range of subjects that covers the entire field of high-pressure mineral physics.

The combination of double-sided laser heating in the diamond anvil cell and detailed chemical analysis of the recovered samples is a promising approach to explore the chemistry of the Earth’s deep interior from the lower mantle to the core. Routine recovery of laser-heated samples coupled with chemical and textural characterization at the submicron scale is the key to expand knowledge of chemical interactions and melting at extreme conditions, particularly in complex systems. Recent technical developments have allowed us to investigate element partitioning and melting relations at pressures approaching the Earth’s inner-core boundary. In this chapter, we review the techniques used for recovering tiny laser-heated samples and analyzing their chemical compositions and quenched textures, while highlighting key experiments that address silicate–metal element partitioning during mantle–core differentiation, silicate melting relations with applications to early magma ocean crystallization and deep mantle melting, and melting relations in iron-alloy systems relevant to the core. The results have drastically expanded our understanding of element redistribution at deep chemical boundaries and the chemical evolution of the deep mantle and the inner core. Finally, we emphasize the need for standardized protocols to obtain consistent, reproducible results and streamlined procedures to promote good practice and increase productivity. A broad collaboration with a systematic approach would further advance the field of high-pressure geochemistry.

Our ability to determine the density (specific volume) as a function of pressure and temperature has drastically improved in the last several decades, with the combination of synchrotron X-ray diffraction and high-pressure techniques such as laser-heated diamond-anvil cell and large-volume multi-anvil press. The improvements are in both pressure–temperature range and data quality, and obtaining high-resolution 2D angle-dispersive diffraction data at over a megabar pressure and above 2,500 K is now routine. In parallel, dynamic compression techniques, such as laser-driven shock wave and magnetically accelerated flyer plate-impact experiments, have provided new ways to measure density at extreme conditions. The combination of static and dynamic compression data allows us to examine internal consistency in pressure determination and establish reliable pressure scales. Internally consistent pressure scales for several pressure standards are emerging through extensive comparison of compression data over a large pressure range and simultaneous measurements of elasticity and density. A concerted effort is needed to further expand and improve measurements under simultaneous high pressure and temperature, particularly at temperatures above 2,500 K, in order to accurately model the thermal pressure. To decipher the compositions of the Earth’s interior based on density observations from seismology requires high accuracy in measuring the subtle compositional effects on the density of mantle and core materials. For a universal understanding of the thermal equations of state of solids, the emphasis should be on reconciling the static and dynamic data of well-studied materials that have substantial overlap in pressure–temperature ranges.

The combination of double-sided laser heating in the diamond anvil cell and detailed chemical analysis of the recovered samples is a promising approach to explore the chemistry of the Earth’s deep interior from the lower mantle to the core. Routine recovery of laser-heated samples coupled with chemical and textural characterization at the submicron scale is the key to expand knowledge of chemical interactions and melting at extreme conditions, particularly in complex systems. Recent technical developments have allowed us to investigate element partitioning and melting relations at pressures approaching the Earth’s inner-core boundary. In this chapter, we review the techniques used for recovering tiny laser-heated samples and analyzing their chemical compositions and quenched textures, while highlighting key experiments that address silicate–metal element partitioning during mantle–core differentiation, silicate melting relations with applications to early magma ocean crystallization and deep mantle melting, and melting relations in iron-alloy systems relevant to the core. The results have drastically expanded our understanding of element redistribution at deep chemical boundaries and the chemical evolution of the deep mantle and the inner core. Finally, we emphasize the need for standardized protocols to obtain consistent, reproducible results and streamlined procedures to promote good practice and increase productivity. A broad collaboration with a systematic approach would further advance the field of high-pressure geochemistry.