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.

ELASTIC AND THERMAL PROPERTIES OF Sr1-xCaxRuO3

2013 ◽  
Vol 27 (17) ◽  
pp. 1350054 ◽  
Author(s):  
RASNA THAKUR ◽  
RAJESH K. THAKUR ◽  
N. K. GAUR
Keyword(s):  
Experimental Data ◽  
Thermal Expansion ◽  
Thermal Properties ◽  
Specific Heat ◽  
Debye Temperature ◽  
Cohesive Energy ◽  
Molecular Force ◽  
Almost All ◽  
Good Agreement ◽  
Rigid Ion Model

We have investigated the elastic and thermal properties of Sr 1-x Ca x RuO 3(0≤x ≤1) perovskite using a modified rigid ion model (MRIM). The trend of variation of our computed specific heat in the temperature range 1 K ≤ T ≤ 1000 K are in good agreement with corresponding experimental data for almost all the compositions (x). The specific heat found to increase with temperature from 1 K to 300 K, while they decrease with concentration (x) for these perovskite ruthenates. Besides, we have reported the thermal properties, like thermal expansion (α), molecular force constant (f), Reststrahlen frequency (υ), cohesive energy (ϕ), Debye temperature (θD) and Gruneisen parameter (γ).

Vibrational Spectrum and Specific Heat of Tantalum

1971 ◽  
Vol 49 (21) ◽  
pp. 2727-2730 ◽  
Author(s):  
Satya Pal
Keyword(s):  
Experimental Data ◽  
Vibrational Spectrum ◽  
Specific Heat ◽  
Debye Temperature ◽  
Fair Agreement ◽  
Dynamical Model

The vibrational spectrum and specific heat of tantalum are calculated on the basis of the lattice dynamical model of Sharma and Joshi. The calculated specific heat and the corresponding equivalent Debye temperature show fair agreement with the experimental data of Clusius and Losa.

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.

Pressure Induced Properties of UXLa1-XS Compound

2016 ◽  
Vol 28 ◽  
pp. 108-114
Author(s):  
Ashok K. Ahirwar ◽  
Mahendra Aynyas ◽  
Sankar P. Sanyal
Keyword(s):  
Experimental Data ◽  
Phase Transition ◽  
Thermal Properties ◽  
Bulk Modulus ◽  
Debye Temperature ◽  
Elastic Constants ◽  
Volume Change ◽  
Mechanical And Thermal Properties ◽  
Phase Transition Pressure ◽  
Crystal Structural

The crystal structural, mechanical and thermal properties of UXLa1-XS compound with different concentrations (x= 0.00, 0.08 and 0.40) are investigated using modified inter-ionic potential theory (MIPT), which parametrically includes the effect of coulomb screening by the delocalized f-electrons. Our calculated values of phase transition pressure, bulk modulus and volume change are agree well with the theoretical and experimental data. We have also calculated the second order elastic constants and Debye temperature of these three concentrations.

THE STATIC DIELECTRIC CONSTANT OF NaCl, KCl, AND KBr AT TEMPERATURES BETWEEN 4.2 °K AND 300 °K

1966 ◽  
Vol 44 (10) ◽  
pp. 2211-2230 ◽  
Author(s):  
M. C. Robinson ◽  
A. C. Hollis Hallett
Keyword(s):  
Experimental Data ◽  
Dielectric Constant ◽  
Debye Temperature ◽  
Relative Error ◽  
Low Temperatures ◽  
Absolute Error ◽  
Static Dielectric Constant ◽  
Good Agreement

Measurements of the static dielectric constant, εst, were made, using a transformer bridge with an absolute error of about 0.5% and a relative error of less than 0.02%. At 300 °K, the values obtained for εst were 5.90, 4.81, and 4.88, while 104(1/εst)(∂εst/∂T)p, was found to be 3.21, 2.93, and 3.10 (°K)−1 for NaCl, KCl, and KBr respectively, in good agreement with other recent measurements.At low temperatures, the curve of εst versus temperature was found to show a minimum, but it has not been found possible to explain all of the observed increase in εst with decreasing temperature below the minimum by the presence of impurities.The variation of εst with temperature is analyzed in detail on the basis of the evaluation made by Szigeti of the anharmonic contribution, G, to the dielectric constant. Estimates of (∂εst/∂T)v, which is equal to (∂G/∂T)v according to Szigeti (1961), have been made from the experimental data, and the curves of (∂εst/∂T)v versus temperature show an unexpected maximum at a temperature near θD/4,where θD is the Debye temperature.

Elastic and Thermal Properties of SrCo1-xScxO3-δ

2014 ◽  
Vol 975 ◽  
pp. 283-287
Author(s):  
Rasna Thakur ◽  
Rajesh K. Thakur ◽  
N.K. Gaur
Keyword(s):  
Thermal Properties ◽  
Specific Heat ◽  
Debye Temperature ◽  
Elastic Constants ◽  
Cohesive Energy ◽  
Second Order ◽  
Grüneisen Parameter ◽  
Gruneisen Parameter ◽  
Rigid Ion Model

We have investigated the elastic and thermal properties for perovskite SrCo1-xScxO3-d, by means of Modified Rigid Ion Model (MRIM). We have also computed the second order Elastic constants (SOECs) and their combinations. Besides we have reported the cohesive energy (f), Debye temperature (θD) and Gruneisen parameter (γ). The variation of specific heat (C) at temperature 15 K≤x≤1000 K is computed for SrCo1-xScxO3-d. The computed properties reproduce well with the available data in literature.

Size and shape dependence of Debye temperature and Raman frequency of nanomaterials

2015 ◽  
Vol 29 (04) ◽  
pp. 1550004
Author(s):  
Raghuvesh Kumar ◽  
Sandhya Bhatt ◽  
Munish Kumar
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Debye Temperature ◽  
Experimental Studies ◽  
Raman Frequency ◽  
Size And Shape ◽  
Shape Dependence ◽  
Simple Theoretical Model ◽  
Good Agreement

A simple theoretical model is developed to study the size and shape dependence of Debye temperature and Raman frequency of nanomaterial. We have studied the effect of size and shape on Debye temperature of nanocrystalline Fe , Co , Al and Ag . The model is extended to study the effect of size and shape on the Raman frequency of nanocrystalline SnO 2, CeO 2 and CdSe . The results obtained are compared with the available experimental data. A good agreement between the theory and experimental data supports the validity of the model developed. We also report the results for nanowire and nanofilm in the absence of experimental data, which may help the researchers engaged in the experimental studies.

SPECIFIC HEAT OF Tb0.5Sr0.5CoO3 CERAMICS

2013 ◽  
Vol 22 ◽  
pp. 391-396
Author(s):  
RASNA THAKUR ◽  
RAJESH K. THAKUR ◽  
N. K. GAUR
Keyword(s):  
Experimental Data ◽  
Thermodynamic Properties ◽  
Bulk Modulus ◽  
Specific Heat ◽  
Debye Temperature ◽  
Cohesive Energy ◽  
Grüneisen Parameter ◽  
Temperature Range ◽  
Proper Interpretation ◽  
Rigid Ion Model

We have investigated the thermal and allied properties of Tb0.5Sr0.5CoO3 for the temperature range 1K≤T≤300K using the Modified Rigid Ion Model (MRIM). The calculated bulk modulus, specific heat, and other thermodynamic properties obtained from MRIM have presented proper interpretation of the experimental data, for Sr ions doped TbCoO3 . In addition, the results on the cohesive energy (φ), Debye temperature (θD) and Gruneisen parameter (γ) are also discussed.

Electronic and optical properties of ZnSxSe1−x alloys

Open Physics ◽  
2009 ◽  
Vol 7 (2) ◽  
Author(s):  
Zhenbao Feng ◽  
Haiquan Hu ◽  
Shouxin Cui
Keyword(s):  
Experimental Data ◽  
Optical Properties ◽  
Band Structure ◽  
Density Of States ◽  
Absorption Edge ◽  
First Principles ◽  
Semiconductor Alloys ◽  
Electronic And Optical Properties ◽  
Spectral Peaks ◽  
Good Agreement

AbstractA series of calculations from first principles have been carried out to study structural, electronic, and optical properties of ZnSxSe1−x alloys. Our results show that the lattice constant scales linearly with sulfur composition. The imaginary parts of the dielectric function are calculated, which are in good agreement with the experimental data. We have also interpreted the origin of the spectral peaks on the basis of band structure and density of states. Additionally, we find that no bowing effect in the absorption edge is observed, unlike other II-VI semiconductor alloys.

ON THE THERMAL EXPANSION OF METALS AT LOW TEMPERATURES

1961 ◽  
Vol 39 (2) ◽  
pp. 263-271 ◽  
Author(s):  
G. K. Horton
Keyword(s):  
Thermal Expansion ◽  
Elastic Constants ◽  
Lattice Dynamics ◽  
Nearest Neighbor ◽  
Force Constants ◽  
Central Force ◽  
Force Model ◽  
Lattice Thermal Expansion ◽  
Interionic Potential ◽  
The Ideal

A theory is developed which correlates the thermal expansion of crystals to the anharmonicity introduced into Born's lattice dynamics by allowing the force constants of the crystal to vary with volume. This is achieved by identifying the force constants with the elastic constants of the crystal by the method of long waves. It is then assumed that it is primarily the volume dependence of the elastic constants that give rise to their temperature variation. A central force nearest and next-nearest neighbor force model analogous to Leighton's is applied to copper. The values of the lattice thermal expansion coefficient and of Grüneisen's parameter are given as a function of the temperature and found to agree quite well with the latest experimental results. It is pointed out that the description of the interionic potential in metals by a two-body central force is certainly a serious oversimplification and that the theory is likely to be more realistic for, say, the ideal inert solid gases, as soon as the experimental data becomes available.

Sign in / Sign up

Export Citation Format

Share Document