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Title: New insights into the enigma of boron carbide inverse molecular behavior

Authors:
; ; ; ;  [1];  [2]
  1. (Hawaii)
  2. (
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
NSFDOE - BASIC ENERGY SCIENCES
OSTI Identifier:
1130095
Resource Type:
Journal Article
Resource Relation:
Journal Name: J. Solid State Chem.; Journal Volume: 215; Journal Issue: 07, 2014
Country of Publication:
United States
Language:
ENGLISH

Citation Formats

Dera, Przemyslaw, Manghnani, Murli H., Hushur, Anwar, Hu, Yi, Tkachev, Sergey, and UC). New insights into the enigma of boron carbide inverse molecular behavior. United States: N. p., 2014. Web. doi:10.1016/j.jssc.2014.03.018.
Dera, Przemyslaw, Manghnani, Murli H., Hushur, Anwar, Hu, Yi, Tkachev, Sergey, & UC). New insights into the enigma of boron carbide inverse molecular behavior. United States. doi:10.1016/j.jssc.2014.03.018.
Dera, Przemyslaw, Manghnani, Murli H., Hushur, Anwar, Hu, Yi, Tkachev, Sergey, and UC). Thu . "New insights into the enigma of boron carbide inverse molecular behavior". United States. doi:10.1016/j.jssc.2014.03.018.
@article{osti_1130095,
title = {New insights into the enigma of boron carbide inverse molecular behavior},
author = {Dera, Przemyslaw and Manghnani, Murli H. and Hushur, Anwar and Hu, Yi and Tkachev, Sergey and UC)},
abstractNote = {},
doi = {10.1016/j.jssc.2014.03.018},
journal = {J. Solid State Chem.},
number = 07, 2014,
volume = 215,
place = {United States},
year = {Thu Jul 17 00:00:00 EDT 2014},
month = {Thu Jul 17 00:00:00 EDT 2014}
}
  • Equation of state and compression mechanism of nearly stoichiometric boron carbide B{sub 4}C were investigated using diamond anvil cell single crystal synchrotron X-ray diffraction technique up to a maximum quasi-hydrostatic pressure of 74.0(1) GPa in neon pressure transmitting medium at ambient temperature. No signatures of structural phase transitions were observed on compression. Crystal structure refinements indicate that the icosahedral units are less compressible (13% volume reduction at 60 GPa) than the unit cell volume (18% volume reduction at 60 GPa), contrary to expectations based on the inverse molecular behavior hypothesis, but consistent with spectroscopic evidence and first principles calculations. Themore » high-pressure crystallographic refinements reveal that the nature of the chemical bonds (two, versus three centered character) has marginal effect on the bond compressibility and the compression of the crystal is mainly governed by the force transfer between the rigid icosahedral structural units. - Graphical abstract: Single crystal measurements of equation of state and compression mechanism of B{sub 4}C show that the icosahedral units are less compressibe than the unit cell volume, despite the threei-ceneterd nature of some icosahedral bonds. - Highlights: • Equation of state and compression mechanism of B{sub 4}C were measured to 75 GPa. • No signatures of structural phase transitions were observed on compression. • Icosahedral units are less compressibe than the unit cell volume. • The nature of the chemical bonds has mariginal effect on the bond compressibility. • The compression is governed by force transfer between the rigid icosahedra.« less
  • The difference in adsorption behavior of hydrocarbons on molybdenum and titanium was used to attain area selective deposition of boron carbide to titanium substrate areas. Hydrocarbons, added to the reaction gas mixture, caused a considerable decrease in the nucleation rate on molybdenum but not on titanium. Hence conditions for selective deposition to titanium areas were obtained. The selectivity was improved by increasing the hydrocarbon concentration in the vapor or by substituting ethylene for methane. This demonstrates that molecular masking of substrate areas can be used to induce or improve the selectivity in a chemical vapor deposition process even at highmore » temperatures (1400 K).« less
  • High-pressure neutron diffraction studies of boron carbide, B[sub 4]C, to 11 GPa show that the icosahedral structural units are 23(4)% more compressible than the structure between them. This inverted-molecular compression is in accordance with qualitative predictions based on models of the bonding, but had not previously been observed directly. The results show the effect of the structural compression on the electrical resistivity to be more complex than present, semiquantitative models suggest.