Pressure-Raman effects in covalent and molecular solids

Weinstein, B. A.; Zallen, Richard

doi:10.1007/3-540-11942-6_26

Cited by 103 publications

(126 citation statements)

References 123 publications

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“…In comparable studies these vibrations have been assigned to Ge-Ge homopolar bonds [27,28], or to distorted rocksalt units [4]. This feature, at 250 cm −1 , was also found to increase in intensity under high pressure conditions [29]. In our simulation we find that these vibrational modes are localized around 3-fold coordinated sulfur atoms, with a corresponding localization length approximately equal to the first-neighbour distance between the central S atom and the 3 Ge first neighbours.…”

Section: Dynamical Propertiesmentioning

confidence: 77%

Vibrational signature of broken chemical order in aGeS2glass: A molecular dynamics simulation

Blaineau

Jund

2004

Phys. Rev. B

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Abstract. Using density functional molecular dynamics simulations, we analyze the broken chemical order in a GeS 2 glass and its impact on the dynamical properties of the glass through the in-depth study of the vibrational eigenvectors. We find homopolar bonds and the frequencies of the corresponding modes are in agreement with experimental data. Localized S-S modes and 3-fold coordinated sulfur atoms are found to be at the origin of specific Raman peaks whose origin was not previously clear. Through the ring size statistics we find, during the glass formation, a conversion of 3-membered rings into larger units but also into 2-membered rings whose vibrational signature is in agreement with experiments.

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Section: Dynamical Propertiesmentioning

confidence: 77%

Vibrational signature of broken chemical order in aGeS2glass: A molecular dynamics simulation

Blaineau

Jund

2004

Phys. Rev. B

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“…The temperaturedependent measurements (total anharmonicity) include both effects. The present measurements of phonon spectra along with the previously reported pressure dependence of the phonon spectra (implicit anharmonicity) can be used to separate [34] the temperature effect at constant volume (explicit or true anharmonicity) as…”

Section: Anharmonicitymentioning

confidence: 91%

Relationship between phonons and thermal expansion in Zn(CN)2and Ni(CN)2from inelastic neutron scattering andab initiocalculations

et al. 2011

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). We have measured the temperature dependence of phonon spectra in these compounds and analyzed them using ab-initio calculations. The spectra of the two compounds show large differences that cannot be explained by simple mass renormalization of the modes involving Zn (65.38 amu) and Ni (58.69 amu) atoms. This reflects the fact that the structure and bonding are quite different in the two compounds. The calculated pressure dependence of the phonon modes and of the thermal expansion coefficient, α V , are used to understand the anomalous behavior in these compounds. Our ab-initio calculations indicate that it is the low-energy rotational modes in Zn(CN) 2 , which are shifted to higher energies in Ni(CN) 2 , that are responsible for the large negative thermal expansion. The measured temperature dependence of the phonon spectra has been used to estimate the total anharmonicity of both compounds. For Zn(CN) 2 , the temperature-dependent measurements (total anharmonicity), along with our previously reported pressure dependence of the phonon spectra (quasiharmonic), is used to separate the explicit temperature effect at constant volume (intrinsic anharmonicity).

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“…While the optical modes and one acoustic mode all shifted linearly to higher wavenumbers with pressure, three of the measured acoustic modes showed no response to increased lattice compression. This is unexpected based on most tetrahedrally coordinated semi-conductors [68]. The mode-Grüneisen parameters were calculated for each mode with only one, the planar acoustic mode (x = 1), having a slightly negative γ, indicating a softening of that mode with pressure.…”

Section: High-pressure Vibrational Spectroscopymentioning

confidence: 97%

High-Pressure, High-Temperature Behavior of Silicon Carbide: A Review

Daviau

Lee

2018

Crystals

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Abstract:The high-pressure behavior of silicon carbide (SiC), a hard, semi-conducting material commonly known for its many polytypic structures and refractory nature, has increasingly become the subject of current research. Through work done both experimentally and computationally, many interesting aspects of high-pressure SiC have been measured and explored. Considerable work has been done to measure the effect of pressure on the vibrational and material properties of SiC. Additionally, the transition from the low-pressure zinc-blende B3 structure to the high-pressure rocksalt B1 structure has been measured by several groups in both the diamond-anvil cell and shock communities and predicted in numerous computational studies. Finally, high-temperature studies have explored the thermal equation of state and thermal expansion of SiC, as well as the high-pressure and high-temperature melting behavior. From high-pressure phase transitions, phonon behavior, and melting characteristics, our increased knowledge of SiC is improving our understanding of its industrial uses, as well as opening up its application to other fields such as the Earth sciences.

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Pressure-Raman effects in covalent and molecular solids

Cited by 103 publications

References 123 publications

Vibrational signature of broken chemical order in aGeS2glass: A molecular dynamics simulation

Vibrational signature of broken chemical order in aGeS2glass: A molecular dynamics simulation

Relationship between phonons and thermal expansion in Zn(CN)2and Ni(CN)2from inelastic neutron scattering andab initiocalculations

High-Pressure, High-Temperature Behavior of Silicon Carbide: A Review

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