A physics-based understanding of the behavior of materials under conditions of high pressure, high temperature, and high strain rate is at the heart of all Department of Energy (DOE)/National Nuclear Security Administration (NNSA) national laboratory programs. Consequently, Lawrence Livermore National Laboratory (LLNL) is a world-leading institute for high pressure materials research with an integrated program of static high pressure shock wave research, high power lasers, condensed matter theories, and computational capabilities. The High Pressure Physics Group leads the experimental static high pressure program at the Laboratory in support of DOE, DOD, and LLNL programs, including NNSA Campaign-2, the Physics Data Research Program, the Laboratory Directed Research and Development Program, DOE's Basic Energy Science organization, and DOD's Office of Munitions.
The research of the High Pressure Physics Group focuses on scientific challenges in condensed matter under extreme conditions of pressure and temperature, including the synthesis and characterization of novel materials. The group uses state-of-the-art experimental facilities and technologies such as third-generation synchrotron sources and laser spectroscopic technologies. Materials of particular interest to the group include f-electron rare earths and actinides, d-band transition metals and transition metal compounds, low-Z elemental solids, and novel superhard and high-energy-density materials of scientific and programmatic importance.
The group consists of highly talented and motivated scientists at all levels: researchers, post-doctoral fellows, pre-doctoral students, and technical and administrative personnel. Much of the research conducted is carried out in a collaborative manner among those scientists and their colleagues.
Squeezed at high temperatures and pressures, carbon dioxide transforms from a molecular solid to a polymeric solid with a structure like quartz [Science, 283, 1510 (1999)]. Raman spectroscopy indicates each carbon atom is bonded to four oxygen atoms, yielding a three-dimensional network like the quartz polymorph of silicon dioxide. The fundamentally different state of CO2 shows interesting nonlinear optical behavior, strongly emitting light at a wavelength that corresponds to the second harmonic of the exciting laser. Once formed, the quartzlike CO2 remains stable at room temperature at pressures above 1 GPa and the researchers hope to able to isolate it at ambient pressures in the near future. One can expect that this new material has high thermal conductivity, just like diamond, and is also a very good candidate for a superhard material similar to diamond and cubic-boron nitride.