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Title: Structural phase transition in deuterated benzil C{sub 14}D{sub 10}O{sub 2}: Neutron inelastic scattering

Abstract

Neutron inelastic scattering has been used to examine the structural phase transition in deuterated benzil C{sub 14}D{sub 10}O{sub 2}. The transition in benzil, in which the unit cell goes from a trigonal P3{sub 1}21 unit cell above T{sub C} to a cell doubled P2{sub 1} unit cell below T{sub C}, leads to the emergence of a Bragg peak at the M-point of the high temperature Brillouin zone. It has previously been suggested that the softening of a transverse optic phonon at the {gamma}-point leads to the triggering of an instability at the M-point causing the transition to occur. This suggestion has been investigated by measuring the phonon spectrum at the M-point for a range of temperatures above T{sub C} and the phonon dispersion relation along the {gamma}-M direction just above T{sub C}. It is found that the transverse acoustic phonon at the M-point is of lower energy than the {gamma}-point optic mode and has a softening with temperature as T approaches T{sub C} from above that is much faster than that of the {gamma}-point optic mode. This behavior is inconsistent with the view that the {gamma}-point mode is responsible for triggering the phase transition. Rather the structural phase transition inmore » benzil appears to be driven by a conventional soft TA mode at the M-point.« less

Authors:
; ; ;  [1];  [2];  [2]
  1. Research School of Chemistry, Australian National University, Canberra 0200 (Australia)
  2. (United States)
Publication Date:
OSTI Identifier:
20788042
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. B, Condensed Matter and Materials Physics; Journal Volume: 73; Journal Issue: 13; Other Information: DOI: 10.1103/PhysRevB.73.134116; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; BRAGG CURVE; BRILLOUIN ZONES; CARBON OXIDES; DEUTERIUM COMPOUNDS; DISPERSION RELATIONS; ENERGY SPECTRA; INELASTIC SCATTERING; INSTABILITY; MONOCLINIC LATTICES; NEUTRON DIFFRACTION; NEUTRONS; ORGANIC COMPOUNDS; PHASE TRANSFORMATIONS; PHONONS; SOLIDS; TRIGONAL LATTICES

Citation Formats

Goossens, D. J., Welberry, T. R., Hagen, M. E., Fernandez-Baca, J. A., Spallation Neutron Source, Oak Ridge National Laboratory, P.O. Box 2008, Tennessee 37831, and Center for Neutron Scattering, Oak Ridge National Laboratory, P.O. Box 2008, Tennessee 37831. Structural phase transition in deuterated benzil C{sub 14}D{sub 10}O{sub 2}: Neutron inelastic scattering. United States: N. p., 2006. Web. doi:10.1103/PHYSREVB.73.1.
Goossens, D. J., Welberry, T. R., Hagen, M. E., Fernandez-Baca, J. A., Spallation Neutron Source, Oak Ridge National Laboratory, P.O. Box 2008, Tennessee 37831, & Center for Neutron Scattering, Oak Ridge National Laboratory, P.O. Box 2008, Tennessee 37831. Structural phase transition in deuterated benzil C{sub 14}D{sub 10}O{sub 2}: Neutron inelastic scattering. United States. doi:10.1103/PHYSREVB.73.1.
Goossens, D. J., Welberry, T. R., Hagen, M. E., Fernandez-Baca, J. A., Spallation Neutron Source, Oak Ridge National Laboratory, P.O. Box 2008, Tennessee 37831, and Center for Neutron Scattering, Oak Ridge National Laboratory, P.O. Box 2008, Tennessee 37831. Sat . "Structural phase transition in deuterated benzil C{sub 14}D{sub 10}O{sub 2}: Neutron inelastic scattering". United States. doi:10.1103/PHYSREVB.73.1.
@article{osti_20788042,
title = {Structural phase transition in deuterated benzil C{sub 14}D{sub 10}O{sub 2}: Neutron inelastic scattering},
author = {Goossens, D. J. and Welberry, T. R. and Hagen, M. E. and Fernandez-Baca, J. A. and Spallation Neutron Source, Oak Ridge National Laboratory, P.O. Box 2008, Tennessee 37831 and Center for Neutron Scattering, Oak Ridge National Laboratory, P.O. Box 2008, Tennessee 37831},
abstractNote = {Neutron inelastic scattering has been used to examine the structural phase transition in deuterated benzil C{sub 14}D{sub 10}O{sub 2}. The transition in benzil, in which the unit cell goes from a trigonal P3{sub 1}21 unit cell above T{sub C} to a cell doubled P2{sub 1} unit cell below T{sub C}, leads to the emergence of a Bragg peak at the M-point of the high temperature Brillouin zone. It has previously been suggested that the softening of a transverse optic phonon at the {gamma}-point leads to the triggering of an instability at the M-point causing the transition to occur. This suggestion has been investigated by measuring the phonon spectrum at the M-point for a range of temperatures above T{sub C} and the phonon dispersion relation along the {gamma}-M direction just above T{sub C}. It is found that the transverse acoustic phonon at the M-point is of lower energy than the {gamma}-point optic mode and has a softening with temperature as T approaches T{sub C} from above that is much faster than that of the {gamma}-point optic mode. This behavior is inconsistent with the view that the {gamma}-point mode is responsible for triggering the phase transition. Rather the structural phase transition in benzil appears to be driven by a conventional soft TA mode at the M-point.},
doi = {10.1103/PHYSREVB.73.1},
journal = {Physical Review. B, Condensed Matter and Materials Physics},
number = 13,
volume = 73,
place = {United States},
year = {Sat Apr 01 00:00:00 EST 2006},
month = {Sat Apr 01 00:00:00 EST 2006}
}