scholarly journals Lattice Dynamical Study and Elastic Property of Europium Telluride (Eute) Crystal

2021 ◽  
Vol 37 (5) ◽  
pp. 1091-1095
Author(s):  
Shyamendra Pratap Singh ◽  
U C Srivastava
Keyword(s):  
Phonon Dispersion ◽  
Dynamical Study ◽  
Pressure Derivative ◽  
Phonon Dispersion Curves ◽  
Europium Telluride ◽  
Range Overlap ◽  
Three Body ◽  
Rigid Shell ◽  
Phonon Properties ◽  
Rigid Ion Model

In the present work authors are reporting complete lattice dynamical properties of Europium telluride (EuTe). The present model works on three body rigid ion model & three body rigid shell model (TRIM & TRSM). The short-range overlap repulsion is operative up to the second neighboring ions. An excellent agreement has been obtained between theory and experiment for their all-phonon properties of (EuTe) like phonon dispersion curves, Debye temperature variations, two-phonon IR/Raman spectra, third-fourth order lattice constant, pressure derivative and anharmonic elastic properties.

AB INITIO STUDY OF PHONON DISPERSION AND ELASTIC PROPERTIES OF L12 INTERMETALLICS Ti3Al AND Y3Al

2013 ◽  
Vol 27 (30) ◽  
pp. 1350224 ◽  
Author(s):  
N. ARIKAN ◽  
M. ERSEN ◽  
H. Y. OCAK ◽  
A. İYIGÖR ◽  
A. CANDAN ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Phonon Dispersion ◽  
High Symmetry ◽  
Generalized Gradient ◽  
Pressure Derivative ◽  
Phonon Dispersion Curves ◽  
Lattice Constants ◽  
Density Functional Perturbation Theory ◽  
Phonon Properties

In this paper, the structural, elastic and phonon properties of Ti 3 Al and Y 3 Al in L1 2( Cu 3 Al ) phase are studied by performing first-principles calculations within the generalized gradient approximation. The calculated lattice constants, static bulk moduli, first-order pressure derivative of bulk moduli and elastic constants for both compounds are reported. The phonon dispersion curves along several high-symmetry lines at the Brillouin zone, together with the corresponding phonon density of states, are determined using the first-principles linear-response approach of the density functional perturbation theory. Temperature variations of specific heat in the range of 0–500 K are obtained using the quasi-harmonic model.

LATTICE DYNAMICS OF MBa2Cu3O7(M=Y, Gd) and YBa2Cu3O6

1989 ◽  
Vol 03 (08) ◽  
pp. 1277-1286 ◽  
Author(s):  
JIE QIN ◽  
YIMIN JIANG
Keyword(s):  
Density Of States ◽  
Phonon Dispersion ◽  
Experimental Investigations ◽  
Phonon Density ◽  
Phonon Density Of States ◽  
Phonon Dispersion Curves ◽  
Rare Earth Atom ◽  
Range Overlap ◽  
Phonon Properties ◽  
Good Agreement

We have presented a lattice dynamical calculation of phonon dispersion curves and one-phonon density of states for the high-T c superconducting MBa 2 Cu 3 O x (M=Y, Gd : x=7, 6) compounds. The model we used is in the framework of a rigid-ion model which includes long-range Coulomb potential and a short-range overlap. The results of calculation give quite good agreement with the available Raman and infrared data, and the measurements of phonon density of states. These results therefore can serve as a guide for further experimental investigations of the phonon properties in M-Ba-Cu-O (M=rare earth atom) system.

scholarly journals LATTICE DYNAMICALSTUDY OF EUROPIUM SULFIDE (EUS) USING TRI & TRSMODEL

2021 ◽  
Vol 9 (01) ◽  
pp. 472-478
Author(s):  
Shyamendra Pratap Singh ◽  
◽  
U.C Srivastava ◽  
K.S Upadhyaya ◽  
◽  
...  
Keyword(s):  
Phonon Dispersion ◽  
Model Parameters ◽  
Third Order ◽  
Dynamical Study ◽  
Satisfactory Description ◽  
Phonon Dispersion Curves ◽  
Europium Sulfide ◽  
Phonon Spectra ◽  
Frame Work ◽  
Three Body

In the present communication authors are reportinglattice dynamical study of Europiumsulfide (EuS).Which is based on the two phenomenological models, by including the effect of three-body interactions(TBI) in the frame work of rigid ion model(TRIM) & rigid shell model (TRSM) with the satisfactory description of all phonon properties.The model parameters of both have used to the phonon spectra for the allowed 48-nonequivalent wave vectors in the first Brillouin zone.The frequencies along the symmetry directions have plotted against the wavevector to obtain the phonon dispersion curves(PDC)from both the models. With the help of available experimentaldata.We have also reportedthe Specific heat variation& Combined density of states (CDS) for complete description of the frequencies for the Brillouin zone included theoretical Debye temperature and elastic property of (second-third order) of EuS. So by using the present model the complete lattice property of EuS is reported successfully.

scholarly journals Lattice Dynamical Study of Platinum by Use of van der Waals Three Body Force Shell Model

2020 ◽  
Author(s):  
U C Srivastava
Keyword(s):  
Shell Model ◽  
Body Force ◽  
Present Model ◽  
Van Der Waals ◽  
Dynamical Study ◽  
Stiffness Constant ◽  
Phonon Spectra ◽  
Three Body ◽  
Rigid Shell ◽  
Fcc Structure

In present article author considered the lattice dynamical study of platinum by use of van der Waals three body force shell model [VTBFSM] due to high stiffness constant C11 and C12 . The present model uses with the frequencies of the optical and vibrational branches in the direction [100] and phonon density of states.The study of phonon spectra are important in determining the mechanica1, electrical and thermodynamical properties of elements and their alloys. The present model incorporates the effect of (VWI) and (TBI) into the rigid shell model with fcc structure, operative up to the second neighbors in short range interactions. The available measured data for platinum (Pt) well agrees with our results.

LATTICE DYNAMICS OF α-LiIO3

1991 ◽  
Vol 05 (17) ◽  
pp. 1167-1173
Author(s):  
YIMIN JIANG ◽  
HONG LIN ◽  
CHENG GOU ◽  
SHIWEN NIU
Keyword(s):  
Lattice Dynamics ◽  
Molecular Crystal ◽  
Field Model ◽  
Phonon Dispersion ◽  
Normal Modes ◽  
Coulomb Force ◽  
Strong Mixing ◽  
Phonon Dispersion Curves ◽  
Good Agreement ◽  
Rigid Ion Model

The phonon dispersion curves of α- LiIO 3, which exhibit a characteristic molecular crystal behaviour, are calculated on the basis of a modified rigid-ion model in which a Born-Mayer potential is used for short-range repulsive interactions between Li ions and [Formula: see text] groups and a central force constant model is used for internal interactions in the [Formula: see text] group. The computed phonon frequencies are in good agreement with those of Raman, infrared and neutron measurements. The calculations show a strong mixing of the pre-normal modes given by Crettez et al.,4 therefore indicating that the long-range Coulomb force may change greatly the assignments previously obtained from a force-field model.

Phonons in SiC from INS, IXS, and Ab-Initio Calculations

2006 ◽  
Vol 527-529 ◽  
pp. 689-694 ◽  
Author(s):  
Dieter Strauch ◽  
B. Dorner ◽  
A.A. Ivanov ◽  
M. Krisch ◽  
J. Serrano ◽  
...  
Keyword(s):  
Density Functional ◽  
Phonon Dispersion ◽  
Inelastic Neutron ◽  
First Principles Calculations ◽  
Phonon Dispersion Curves ◽  
Functional Methods ◽  
X Ray Scattering ◽  
Density Functional Perturbation Theory ◽  
Phonon Properties

Preliminary results for the phonon dispersion curves of hexagonal 4H-SiC from experimental inelastic neutron (INS) and X-ray scattering (IXS) are reported and contrasted with those of cubic 3C-SiC and silicon. The experimental frequencies and scattering intensities are in excellent agreement with those from first-principles calculations using density-functional methods. The relative merits of the two experimental techniques and aspects of the density functional perturbation theory and the so-called frozen phonon method for the determination of the basic phonon properties are briefly outlined.

The Pressure Dependence of Structural, Electronic, Mechanical, Vibrational, and Thermodynamic Properties of Palladium-Based Heusler Alloys

2017 ◽  
Vol 72 (9) ◽  
pp. 843-853 ◽  
Author(s):  
Cansu Çoban
Keyword(s):  
Thermodynamic Properties ◽  
Elastic Constants ◽  
Phonon Dispersion ◽  
Electronic Band Structure ◽  
Heusler Alloys ◽  
Dispersion Curves ◽  
Pressure Derivative ◽  
Electronic Band ◽  
Phonon Dispersion Curves ◽  
The Stability

AbstractThe pressure dependent behaviour of the structural, electronic, mechanical, vibrational, and thermodynamic properties of Pd2TiX (X=Ga, In) Heusler alloys was investigated by ab initio calculations. The lattice constant, the bulk modulus and its first pressure derivative, the electronic band structure and the density of states (DOS), mechanical properties such as elastic constants, anisotropy factor, Young’s modulus, etc., the phonon dispersion curves and phonon DOS, entropy, heat capacity, and free energy were obtained under pressure. It was determined that the calculated lattice parameters are in good agreement with the literature, the elastic constants obey the stability criterion, and the phonon dispersion curves have no negative frequency which shows that the compounds are stable. The band structures at 0, 50, and 70 GPa showed valence instability at the L point which explains the superconductivity in Pd2TiX (X=Ga, In).

Structural, electronic, elastic, thermodynamic and phonon properties of LaX (X = Cd, Hg and Zn) compounds in the B2 phase

2016 ◽  
Vol 30 (24) ◽  
pp. 1650169 ◽  
Author(s):  
Osman Örnek ◽  
Nihat Arıkan
Keyword(s):  
Density Functional ◽  
Phonon Dispersion ◽  
Band Structures ◽  
Pressure Derivative ◽  
Electronic Band ◽  
Lattice Constants ◽  
Density Functional Perturbation Theory ◽  
Densities Of States ◽  
Electronic Band Structures ◽  
Phonon Properties

The ab initio computations have been performed to examine the structural, elastic, electronic and phonon properties of cubic [Formula: see text] [Formula: see text], [Formula: see text] and [Formula: see text] compounds in the [Formula: see text] phase. The optimized lattice constants, bulk modulus, and its pressure derivative and elastic constants are evaluated and compared with available data. Electronic band structures and total and partial densities of states (DOS) have been derived for [Formula: see text] [Formula: see text], [Formula: see text] and [Formula: see text] compounds. The electronic band structures show metallic character; the conductivity is mostly governed by [Formula: see text]-[Formula: see text] states for three compounds. Phonon-dispersion curves have been obtained using the first-principle linear-response approach of the density-functional perturbation theory. The specific heat capacity at a constant volume [Formula: see text] of [Formula: see text] [Formula: see text], [Formula: see text] and [Formula: see text] compounds are calculated and discussed.

Phonon Properties of Americium Sulphide

2016 ◽  
Vol 28 ◽  
pp. 125-128
Author(s):  
Balwant Singh Arya ◽  
Mahendra Aynyas ◽  
Sankar P. Sanyal
Keyword(s):  
Present Model ◽  
Phonon Dispersion ◽  
Dispersion Curves ◽  
Phonon Interaction ◽  
Phonon Dispersion Curves ◽  
Electron Phonon Interaction ◽  
Breathing Motion ◽  
Shell Models ◽  
Phonon Properties

We have reported the phonon properties of AmS by using breathing shell models (BSM) which includes breathing motion of electrons of the Am atoms due to f-d hybridization. The phonon dispersion curves, density of states and specific heat calculated from present model. The calculated phonon dispersion curves of AmS are presented follow the same trend as observed in uranium sulphide. We have discussed the significance of this approach in predicting the phonon dispersion curves of this compound and examine the role of electron-phonon interaction.

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.

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