Phonon Dispersion in ZnSe

1972 ◽  
Vol 50 (21) ◽  
pp. 2596-2604 ◽  
Author(s):  
J. C. Irwin ◽  
J. LaCombe
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Specific Heat ◽  
Single Crystals ◽  
Raman Spectra ◽  
Density Of States ◽  
Brillouin Zone ◽  
Critical Points ◽  
Phonon Dispersion ◽  
Zone Boundary

Second-order Raman spectra have been obtained from oriented single crystals of ZnSe. The spectra have been interpreted and the results have been used to determine the zone boundary frequencies at the critical points X, L, and W. The resulting set of frequencies are consistent with known polarization selection rules and with a theoretical model. The frequencies in turn serve to determine the parameters in the theoretical model and the resulting model has been used to calculate the phonon dispersion throughout the Brillouin zone, the density of states, and the specific heat. The results are compared to the small amount of experimental data that is available.

Second-Order Raman Spectra of Fluorites. I. Critical Point Analysis

1972 ◽  
Vol 50 (8) ◽  
pp. 849-857 ◽  
Author(s):  
N. Krishnamurthy ◽  
V. Soots
Keyword(s):  
Critical Point ◽  
Single Crystals ◽  
Raman Spectra ◽  
Brillouin Zone ◽  
Critical Points ◽  
Photon Counting ◽  
Second Order ◽  
Selection Rules ◽  
Point Analysis ◽  
Critical Point Analysis

With the use of a high-powered Ar+ laser and conventional photon counting techniques it has been possible to observe the second-order Raman spectra of single crystals of CaF2, SrF2, BaF2, and PbF2. The symmetries of the various parts of the spectra of the latter two were determined by using oriented single crystals of these two fluorides. The main features of the observed spectra have been analyzed, with the aid of group-theoretical selection rules, in terms of calculated phonon frequencies at the critical points of the Brillouin zone of these crystals.

LATTICE DYNAMICS OF NICKEL

1967 ◽  
Vol 45 (5) ◽  
pp. 1655-1660 ◽  
Author(s):  
S. P. Singh
Keyword(s):  
Experimental Data ◽  
Specific Heat ◽  
Debye Temperature ◽  
Density Of States ◽  
Elastic Constants ◽  
Lattice Dynamics ◽  
Vibration Spectrum ◽  
Force Constants ◽  
Effective Force ◽  
Good Agreement

The vibration spectrum of the nickel lattice has been calculated using the simple de Launay method with values for the effective force constants determined from published experimental data for the elastic constants. The density-of-states curve reproduces the same general features found by Birgeneau et al. (1964) using a fourth-neighbor model. The Debye temperature at 0 °K is found to be 474 °K in good agreement with the experimental value of 468 °K, and the calculated variation of the Debye temperature with temperature agrees quite well with that deduced from measurements of the specific heat.

Extended Van Hove Singularity in Raman Spectra of High-Tc Superconductors

1998 ◽  
Vol 12 (24) ◽  
pp. 2455-2473 ◽  
Author(s):  
O. V. Misochko ◽  
E. Ya. Sherman
Keyword(s):  
Experimental Data ◽  
Raman Scattering ◽  
Raman Spectra ◽  
Brillouin Zone ◽  
Van Hove Singularity ◽  
High Tc Superconductors ◽  
High Tc ◽  
Superconducting Cuprates ◽  
Different Parts

We consider theoretically and experimentally how an extended van Hove singularity manifests itself in electronic and phonon Raman scattering in superconducting cuprates. Our analysis and experimental data shows that in the case of singularity carriers redistribution between different parts of the Brillouin zone and/or electronic bands is a common feature of both the electronic and phonon Raman scattering.

Experimental evidence for the Fermi surface overlap effect in ε-phase Ag—Zn alloys, obtained from low temperature specific heats

1975 ◽  
Vol 343 (1634) ◽  
pp. 375-387 ◽  
Keyword(s):  
Theoretical Model ◽  
Low Temperature ◽  
Specific Heat ◽  
Brillouin Zone ◽  
Band Gaps ◽  
Electronic Specific Heat ◽  
Specific Heats ◽  
Ε Phase ◽  
Specific Heat Coefficient ◽  
Zn Alloys

Measurements of the electronic specific heat coefficient and of the limiting Debye temperature are reported for ten Ag-Zn alloys in the range of the h.e.p. ε-phase. After a correction for the electron-phonon enhancement, the trend of the electronic specific heat coefficient is consistent with a nearly rigid band behaviour, showing a general decrease of the density of states at the Fermi level when the corners of the Brillouin zone are filled. A slight deviation from this trend occurs at electron concentration values exceeding approximately 1.85 5 , in agreement with other measured properties and confirming a theoretical model involving overlaps of electrons across the {00.2} planes of the Brillouin zone. The estimated band gaps are of the order of 2 eV. I t appears that whereas in the dilute rj-phase alloys of zinc with silver the rigid band condition is not valid the opposite is true in the concentrated ε-phase alloys.

scholarly journals LATTICE DYNAMICAL STUDY OF TITANIUM (TI) BY USING CGW-VTBFS MODEL

2021 ◽  
Vol 9 (07) ◽  
pp. 124-129
Author(s):  
U.C Srivastava ◽  
◽  
Shyamendra Pratap Singh ◽  
Keyword(s):  
Experimental Data ◽  
Specific Heat ◽  
Shell Model ◽  
Body Force ◽  
Phonon Dispersion ◽  
Dispersion Curves ◽  
Dynamical Study ◽  
Phonon Dispersion Curves ◽  
Phonon Dynamics ◽  
Experimental Values

In measurements of the phonon dynamics of bcc Titanium (Ti), In the present paper we have reported the lattice dynamical calculations which are performed by using the Clark-Gazis-Wallis (CGW) and Van der Waalsthree body force shell model (VTBFS).The theory is used to compute the phonon dispersion curves(PDC), the Specific heat variation &frequency distribution with the used temperature. The frequencies along the symmetry directions have plotted against the wavevector to obtain the phonon dispersion curves(PDC)from the present models, with the help of available experimental values. The obtained results are agreed well with experimental data.

scholarly journals Resonance Raman Spectra of Erythrocytes: Vibron Model

2018 ◽  
Vol 34 (5) ◽  
pp. 2671-2672
Author(s):  
J. Vijayasekhar
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Raman Spectra ◽  
Vibrational Spectra ◽  
Resonance Raman ◽  
Theoretical Method ◽  
Vibrational Modes ◽  
One Dimensional ◽  
Resonance Raman Spectra ◽  
The One

In this paper, vibrational spectra (infrared and Raman) of oxygenated and deoxynated functional erythrocytes are calculated using theoretical method “Vibron model” in the one-dimensional [U(2)] framework. The determined vibrational modes by Vibron model are compared with experimental data. It has been observed that results from the theoretical model reveal near to the exact, reliable with the experimental data.

Ab initio investigation of the electronic, lattice dynamic and thermodynamic properties of ScCd intermetallic alloy

2016 ◽  
Vol 30 (24) ◽  
pp. 1650175
Author(s):  
B. I. Adetunji ◽  
A. S. Olayinka ◽  
J. B. Fashae ◽  
V. C. Ozebo
Keyword(s):  
Heat Capacity ◽  
Thermodynamic Properties ◽  
Specific Heat ◽  
Density Of States ◽  
Specific Heat Capacity ◽  
Density Functional ◽  
Phonon Dispersion ◽  
Harmonic Approximation ◽  
Generalized Gradient ◽  
Vibrational Free Energy

The electronic structures, lattice dynamics and thermodynamic properties of rare-earth intermetallic ScCd alloy are studied by the first-principles plane-wave pseudopotential method within the generalized gradient approximation in the framework of density functional pertubation theory. The band structure, density of states, phonon dispersion frequencies, vibrational free energy [Formula: see text], specific heat capacity [Formula: see text] and entropy are studied between 0 K and 1500 K. Finally, using the calculated phonon density of states, the thermodynamic properties are determined within the quasi-harmonic approximation and a value of 47.9 (J/mol⋅K) at 300 K for specific heat capacity of ScCd is predicted.

Critical point analysis of cubic ZnS

1970 ◽  
Vol 48 (21) ◽  
pp. 2477-2480 ◽  
Author(s):  
J. C. Irwin
Keyword(s):  
Theoretical Model ◽  
Critical Point ◽  
Infrared Spectra ◽  
Critical Points ◽  
Second Order ◽  
Experimental Results ◽  
Zone Boundary ◽  
Point Analysis ◽  
Critical Point Analysis

An interpretation of the second-order Raman and infrared spectra of cubic ZnS is given. A set of values is obtained for the phonon frequencies at the zone boundary critical points X, L, and W. These values are consistent with both the experimental results and a theoretical model. The frequencies obtained are compared with those proposed by previous workers.

Effect of Tensile Strain on Thermal Properties of Graphene

2014 ◽  
Vol 1661 ◽  
Author(s):  
Ayman Salman Alofi ◽  
Gyaneshwar P. Srivastava
Keyword(s):  
Thermal Conductivity ◽  
Relaxation Time ◽  
Thermal Properties ◽  
Specific Heat ◽  
Density Of States ◽  
Tensile Strain ◽  
Phonon Dispersion ◽  
Analytical Expressions ◽  
Vibrational Density ◽  
Phonon Dispersion Relations

ABSTRACTWe have employed a semicontinuum model to investigate the effect of tensile strain on thermal properties of graphene. Analytical expressions derived by Nihira and Iwata for phonon dispersion relations and vibrational density of states are employed, based on the semicontinuum model proposed by Komatsu and Nagamiya. The thermal conductivity is computed within the framework of Callaway’s effective relaxation time theory. It is found that thermal properties of graphene are quite sensitive to tensile strain. In the presence of tensile strain, the specific heat increases but the thermal conductivity decreases.

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