High Pressure Collaborative Access Team

News

Graduate students from University of Tennessee, Knoxville, Louisiana State University, University of Maryland, Rice University, University of California, Berkeley, University of Illinois at Urbana, University of Cincinnati, and University of Notre Dame attended the 2018 NX School at 16-BMD

HPCAT hosted a group of eight graduate students as part of the 2018 Neutron and X-ray School on… more

GSECARS, HPCAT and Barnett Technical Services hosted a hands-on workshop on May 10, 2018 dedicated… more

HPCAT enjoys the opportunity to participate in S.T.E.M. outreach activities each year.

On April 19, 2018, HPCAT hosted Chicago-area High School girls for the Science Careers in Search of… more

Itaru Ohira is a visiting scientist to HPCAT for the next year from Tohoku University, Japan, where… more

HPCAT Workshop on Time-resolved Synchrotron Techniques

A Workshop on high-pressure time-resolved synchrotron techniques was held on September 25-27, 2014… more

This report documents the proceedings of the workshop, "Advances in Matter Under Extreme Conditions… more

High Pressure Collaborative Access Team

High Pressure Collaborative Access Team (HPCAT) is a research consortium to advance compression science in multidisciplinary fields using synchrotron radiation.

05/22/2018

Figure caption: Inelastic x-ray scattering data revealing oxygen K-edge in B2O3 glass at pressures ranging from 1 bar to over 100 GPa.

Inelastic x-ray scattering at megabar pressures

When compressed above megabar pressures (>100 GPa), glasses may undergo structural transitions into more densely packed networks that differ from those at ambient pressure. Inelastic x-ray scattering (IXS, or X-ray Raman scattering), which can probe core electron excitation from glasses in a… more

04/3/2018

Figure caption: A selected crystallite of the hexagonal phase (Fe,Al)OOH at 110 GPa.

An ultradense hydrous phase as a candidate for water storage in the lower mantle

Recent discoveries of several stable dense hydrous minerals at high pressure–temperature conditions have led to an important implication of a massive water reservoir in the Earth’s lower mantle. A research team used HPCAT facility and demonstrated that (Fe,Al)OOH can be stabilized in a hexagonal… more

03/19/2018

Figure caption: (a) Pressure dependence of Yb valence. (b) XANES fits under the pressure of 1.4 GPa. (c) A typical fitting result in a mixed-valence state at 41.3 GPa.

YbB6 becoming a topological Kondo insulator under pressure

Topological Kondo insulator possesses characteristics of both the strong electron correlations and the topological configurations, as shown in a mixed-valence material SmB₆. YbB₆ is a structural analog of SmB₆, but remains controversial whether compressed YbB… more

03/19/2018

Figure caption: (a) Unit cell of Cu-S-M9. Atoms are represented by their thermal ellipsoids at the 50% probability level. Copper, sulfur, carbon and boron atoms are represented by red, yellow, grey and pink ellipsoids, respectively. Hydrogen atoms and interstitial solvent (toluene) molecules are omitted for clarity. (b) Cu-S-M9 molecule showing the Cu4S4 mechanophore surrounded by M9 ligands, represented by polyhedra.

Pressure enabling “molecular anvils” and modifying the energy landscape of chemical reactions

By engineering molecules with mechanically heterogeneous components with a compressible (‘soft’) mechanophore and incompressible (‘hard’) ligands, a research team has created ‘molecular anvils’, resulting in isotropic stress that leads to relative motions of the rigid ligands, anisotropically… more

02/13/2018

Caption: An illustration shows how rapid decompression is the key to observing low-density liquid water. Low density water mediates the rapid decompression transition from ice-VIII to ice Ic.

Low-density liquid water upon rapid decompression

At temperatures (<319 K or <46 ^oC) where life is sustained, water is an abnormal liquid, having a number of anomalous properties. For instance, water displays minima of isobaric heat capacity at 308 K and isothermal compressibility at 319 K which are related to entropy and… more

02/7/2018

Figure caption: Structure factor S(Q) of MgSiO3 glass up to 111 GPa, displayed by a vertical offset of +0.42 for B and +0.48 for C and D.

Structure of MgSiO3 glass at pressures near the Earth’s core-mantle boundary

Knowledge on the structure and properties of silicate magma under extreme pressure plays an important role in understanding the nature and evolution of Earth’s deep interior. However, such information is scarce owing to experimental challenges. Using a recently developed double-stage Paris-… more

02/7/2018

Figure caption: The evolution of the CaF2 unit cell volume versus stress/pressure obtained from dynamic (shock at DCS) and from static compression (DAC at HPCAT).

Real-time observations of the kinetics of a shock-driven phase transition using x-ray diffraction

Understanding the behavior of solids under shock compression, including transformations, their pathways, and kinetics, lies at the core of contemporary static and dynamic compression science. A team led by scientists from Sandia National Laboratories is leveraging the capabilities of two sectors… more

01/29/2018

$Figure caption: NCD micro-anvils grown on single crystal diamond anvils and mounted in an opposed anvil configuration before pressurization in a diamond anvil cell. The entire diamond anvil including the NCD micro-anvil has been deposited with a one micron thick layer of tungsten metal for pressure measurement by x-ray diffraction.$

Generating pressures of 500 GPa using nanocrystalline diamond as second stage anvils

Single crystal diamond is the hardest known material and widely used in studies on materials under extreme conditions. Nanocrystalline diamond (NCD) possesses hardness comparable to that of single crystal diamond, while also demonstrating increased fracture toughness and yield strength. Thus,… more

High Pressure Collaborative Access Team (HP-CAT) High Pressure Collaborative Access Team (HP-CAT)

High Pressure Collaborative Access Team