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compreslogotiny.jpg COMPRES, the Consortium for Materials Properties Research in Earth Sciences is a community-based consortium whose goal is to enable Earth Science researchers to conduct the next generation of high-pressure science on world-class equipment and facilities. It facilitates the operation of beam lines, the development of new technologies for high pressure research, and advocates for science and educational programs to the various funding agencies.

High Pressure Science at NSLS-II

NSLS-II announces successful beamline development proposals

3 COMPRES - Affiliated Proposals Awarded Type I Status for Beamline Development:

  • 4-Dimensional Studies in Extreme Environments; Spokesperson: Donald J. Weidner
  • Time-resolved X-ray Diffraction and Spectroscopy Under Extreme Conditions; Spokesperson: Alexander Goncharov
  • Frontier Synchrotron Infrared Spectroscopy Beamline Under Extreme Conditions; Spokesperson: Zhenxian Liu

Additional Information about the NSLS:II project can be found here

COMPTECH

COMPRES Technology Center (COMPTECH ) is COMPRES's presence at the Advanced Photon Source, Argonne National Laboratory. It provides tools, software, development and support for High-pressure research at APS.

comptech.compres.us

 

 

Support

nsf1.jpgNSF supports COMPRES, the Consortium for Materials Properties Research in Earth Sciences under NSF Cooperative Agreement EAR 11-43050.


Atomistic insight into vicosity and density of silicate melts under pressure

 Research From A COMPRES Infrastructure Development Project

Wang, Yanbin, Sakamaki, T., Skinner, L., Jing, Z., Yu, T., Kono, Y., Park, C., Shen, G., Rivers, M., and Sutton, S., NATURE COMMUNICATIONS | 4:2117 | DOI: 10.1038/ncomms4241
wangetal2014.jpg

Figure: Different pressure dependence on viscosities of polymerized and depolymerized melts.  (a) Viscosities of polymerized melts (blue symbols and shaded area), generally with higher values at 1 atm, exhibit negative pressure dependence at low pressures.  The range of viscosity variation decreases with pressure (blue shaded area).  For depolymerized melts, viscosities generally increase with pressure (orange symbols and shaded area).  Typical experimental uncertainties are given.  (b) Normalized viscosities with respect to their 1 atm values.  Pressure turnover is clearly seen for the polymerized melts (blue symbols and shaded area).  Approximate values of NBO/T for the polymerized melts are given on the right side of the figure.  Normalized viscosities of depolymerized melts (orange symbols, with NBO/T≈2) fall in a very narrow range and are not shaded. 

 

A defining characteristic of silicate melts is the degree of polymerization, which dictates viscosity and affects compressibility.  While viscosity of depolymerized melts increases with pressure consistent with free volume theory, isothermal viscosity of polymerized melts decreases with pressure up to ~3 - 5 GPa, above which it turns over to normal (positive) pressure dependence.  This viscosity turnover in polymerized liquids corresponds to the tetrahedral packing limit, below which the structure is compressed through tightening of the inter-tetrahedral bond angle, resulting in high compressibility, continual breakup of tetrahedral connectivity, and viscosity decrease with increasing pressure.  Above the turnover pressure, Si and Al coordination increases to allow further packing, with increasing viscosity and density.  These structural responses prescribe the distribution of melt viscosity and density with depth and may play an important role in magma transport in terrestrial planetary interiors.  

posted Feb. 27, 2014

"Research Performed at COMPRES-supported Beamlines X17C and U2A"

Signatures of a Pressure-Induced Topological Quantum Phase Transition in BiTeI

Xi, X. at al., 2013,  Physical Review Letters 111(15): 155701

 

xihilite2014.jpg

 

Figures: (a) The crystal structure of BiTeI with unit cell lengths, a and c. (b) Pressure dependence of the crystallographic c/a ratio (circles) from XRD and the plasma frequency ωp from IR spectroscopy (squares). The minimum in ωp indicates band gap closing and re-opening, signaling the transition.

 

Pressure induced the polar semiconductor BiTeI into a “topological insulator” state. This is the first case of a pressure-induced topological insulator and its discovery could help scientists find ideal TIs for future electronics applications.