Electron density topology of high-pressure Ba8Si46 from a combined Rietveld and maximum-entropy analysis

John S. Tse, Roxana Flacau, Serge Desgreniers, Toshiaki Iitaka, and J. Z. Jiang
Phys. Rev. B 76, 174109 – Published 15 November 2007

Abstract

Under pressure, Ba8Si46 is found to undergo an isostructural transition, as observed by Raman spectroscopy, extended x-ray-absorption fine structure, and x-ray diffraction. Rietveld analysis of the x-ray diffraction data shows a homothetic contraction of the host lattice after the structural transition at 17GPa. Using the Rietveld and maximum-entropy methods, we have performed an analysis of high resolution x-ray diffraction patterns collected from ambient to 30GPa obtained in a diamond anvil cell using He as a quasihydrostatic pressure transmitting medium. The results indicate unambiguously that the homothetic phase transition at about 17GPa is due to an extensive rehybridization of the Si atoms leading to a transfer of valence electrons from the bonding to the interstitial region. Consequently, the Si–Si bonds are weakened substantially at high density, leading to an abrupt collapse of the unit cell volume without a change in crystalline structure. The transition pressure and the change in the chemical bonding are remarkably similar to that observed in elemental Si–V.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Received 22 January 2007

DOI:https://doi.org/10.1103/PhysRevB.76.174109

©2007 American Physical Society

Authors & Affiliations

John S. Tse1,2, Roxana Flacau2, Serge Desgreniers2, Toshiaki Iitaka3, and J. Z. Jiang4

  • 1Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5E2
  • 2Laboratoire de Physique des Solides Denses, Department of Physics, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5
  • 3Computational Astrophysics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
  • 4International Center for New-Structured Materials (ICNSM) and Laboratory of New-Structured Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, People’s Republic of China

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 76, Iss. 17 — 1 November 2007

Reuse & Permissions
Access Options
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review B

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×