Phonon density of states of tetracyanoethylene from coherent inelastic neutron scattering at Dhruva reactor

Pramana ◽  
1989 ◽  
Vol 33 (5) ◽  
pp. 595-602 ◽  
Author(s):  
S L Chaplot ◽  
R Mukhopadhyay ◽  
P R Vijayaraghavan ◽  
A S Deshpande ◽  
K R Rao
Keyword(s):  
Neutron Scattering ◽  
Density Of States ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Phonon Density ◽  
Phonon Density Of States

PHONON DENSITY OF STATES IN THE SUPERCONDUCTING Y-Ba-Cu-O SYSTEM

1989 ◽  
Vol 03 (01) ◽  
pp. 55-59
Author(s):  
J.H. RUAN ◽  
A.S. YU ◽  
J. QIN ◽  
C. GOU ◽  
T.H. YANG ◽  
...  
Keyword(s):  
Energy Spectrum ◽  
Neutron Scattering ◽  
Density Of States ◽  
Inelastic Neutron Scattering ◽  
Meissner Effect ◽  
Inelastic Neutron ◽  
Scattering Method ◽  
Phonon Density ◽  
Large Decrease ◽  
Phonon Density Of States

The generalized phonon density of states for the high-T c superconductor YBa 2 Cu 3 O 7.1 with high Meissner effect (50%) and for its retreated sample with low Meissner effect (15%) at T=300 K and T=86 K respectively was measured by using inelastic neutron scattering method. The density of states of the superconductor YBa 2 Cu 3 O 7.1 at temperatures of both 300 K and 86 K shows a similar energy spectrum below 95 meV. However, above this energy there are evident softening of modes at 86 K. In addition, a large decrease of 92 meV peak in the density of states for a sample with lower Meissner effect was observed, this effect is supposed to be a result of an increase of vacancies on O 4 site.

Phonon density of states of model ferroelectrics

2010 ◽  
Vol 1262 ◽  
Author(s):  
Narayani Choudhury ◽  
Alexander I Kolesnikov ◽  
Helmut Schober ◽  
Eric J Walter ◽  
Mark Johnson ◽  
...  
Keyword(s):  
Density Of States ◽  
First Principles ◽  
Density Functional ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Cubic Phase ◽  
Phonon Density ◽  
Phonon Density Of States ◽  
Phonon Spectra ◽  
Quantum Paraelectric

AbstractFirst principles density functional calculations and inelastic neutron scattering measurements have been used to study the variations of the phonon density of states of PbTiO3 and SrTiO3 as a function of temperature. The phonon spectra of the quantum paraelectric SrTiO3 is found to be fundamentally distinct from those of ferroelectric PbTiO3 and BaTiO3. SrTiO3 has a large 70-90 meV phonon band-gap in both the low temperature antiferrodistortive tetragonal phase and in the high temperature cubic phase.Key bonding changes in these perovskites lead to spectacular differences in their observed phonon density of states.

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