64 citations · 251 across the 14 of their papers we have counts for
14 papers
A latent heat method to detect melting and freezing of metals at megabar pressures
Zachary M. Geballe, Nicholas Holtgrewe, Amol Karandikar +3
The high-pressure melting curves of metals provide simple and useful tests for theories of melting, as well as important constraints for the modeling of planetary interiors. Here,…
Polymorphism of superionic ice
Vitali B. Prakapenka, Nicholas Holtgrewe, Sergey S. Lobanov +1
Water is abundant in natural environments but the form it resides in planetary interiors remains uncertain. We report combined synchrotron X-ray diffraction and optical spectroscop…
Low thermal conductivity of iron-silicon alloys at Earth core conditions with implications for the geodynamo
Wen-Pin Hsieh, Alexander F. Goncharov, Stéphane Labrosse +5
Earth core is composed of iron (Fe) alloyed with light elements, e.g., silicon (Si). Its thermal conductivity critically affects Earth thermal structure, evolution, and dynamics, a…
Blocked radiative heat transport in the hot pyrolitic lower mantle
Sergey S. Lobanov, Nicholas Holtgrewe, Gen Ito +8
The heat flux across the core-mantle boundary (QCMB) is the key parameter to understand the Earth/s thermal history and evolution. Mineralogical constraints of the QCMB require dec…
Opaque Lowermost Mantle
Sergey S. Lobanov, François Soubiran, Nicholas Holtgrewe +3
Earth/s lowermost mantle displays complex geological structures that likely result from heterogeneous thermal and electromagnetic interaction with the core. Geophysical models of t…
Insulator-metal transition in liquid hydrogen and deuterium
Shuqing Jiang, Nicholas Holtgrewe, Zachary M. Geballe +4
The insulator-to-metal transition in dense fluid hydrogen is an essential phenomenon to understand gas giant planetary interiors and the physical and chemical behavior of highly co…
Observation of a metastable intermediate during solid-solid phase transformation in response to rapid compression
Michael R. Armstrong, Harry B. Radousky, Ryan A. Austin +23
In order to probe the mechanism of solid-solid phase transformations, we have applied ultrafast shock wave compression (120 picosecond duration) and ultrashort (130 femtosecond) x-…
Metallization and molecular dissociation of dense fluid nitrogen
Shuqing Jiang, Nicholas Holtgrewe, Sergey S. Lobanov +4
Diatomic nitrogen is an archetypal molecular system known for its exceptional stability and complex behavior at high pressures and temperatures, including rich solid polymorphism,…
Uranium polyhydrides at moderate pressures: prediction, synthesis, and expected superconductivity
Ivan A. Kruglov, Alexander G. Kvashnin, Alexander F. Goncharov +7
Hydrogen-rich hydrides attract great attention due to recent theoretical (1) and then experimental discovery of record high-temperature superconductivity in H3S (Tc = 203 K at 155…
Radiative conductivity and abundance of post-perovskite in the lowermost mantle
Sergey S. Lobanov, Nicholas Holtgrewe, Jung-Fu Lin +1
Thermal conductivity of the lowermost mantle governs the heat flow out of the core energizing planetary-scale geological processes. Yet, there are no direct experimental measuremen…
Reduced radiative conductivity of high and low spin FeO6 octahedra in the Earth's lower mantle
Sergey S. Lobanov, Nicholas Holtgrewe, Alexander F. Goncharov
The ability of Earths mantle to conduct heat by radiation is determined by optical properties of mantle phases. Optical properties of mantle minerals at high pressure are accessibl…
Synthesis of Polar Ordered Oxynitride Perovskite
Muhtar Ahart, Maddury Somayazulu, Rajasekarakumar Vadapoo +5
For decades, numerous attempts have been made to produce polar oxynitride perovskites, where some of the oxygen are replaced by nitrogen, but a polar ordered oxynitride has never b…
Stable magnesium peroxide at high pressure
Sergey S. Lobanov, Qiang Zhu, Nicholas Holtgrewe +4
Rocky planets are thought to comprise compounds of Mg and O as these are among the most abundant elements, but knowledge of their stable phases may be incomplete. MgO is known to b…
Backbone NxH Compounds at High Pressures
Alexander F. Goncharov, Nicholas Holtgrewe, Guangrui Qian +11
Optical and synchrotron x-ray diffraction diamond anvil cell experiments have been combined with first principles theoretical structure predictions to investigate mixed N2 and H2 u…