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.

Contributions to Silicon-Hydrogen Bond-Stretching Frequency in Amorphous Si Alloys

1992 ◽  
Vol 258 ◽  
Author(s):  
Z. Jing ◽  
J. L. Whitten ◽  
G. Lucovsky
Keyword(s):  
Experimental Data ◽  
Hydrogen Bond ◽  
Dielectric Constant ◽  
Ab Initio ◽  
Effective Dielectric Constant ◽  
Bond Energies ◽  
Calculated Frequency ◽  
Bond Stretching ◽  
Amorphous Si ◽  
Good Agreement

ABSTRACTWe have performed ab initio calculations and determined the bond-energies and vibrational frequencies of Si-H groups that are: i) attached to Si-atoms as their immediate, and also more distant neighbors; and ii) attached to three O-atoms as their immediate neighbors, but are connected to an all Si-atom matrix. These arrangements simulate bonding geometries on Si surfaces, and the calculated frequency for i) is in good agreement with that of an Si-H group on an Si surface. To compare these results with a-Si:H alloys it is necessary to take into account an additional factor: the effective dielectric constant of the host. We show how to do this, demonstrating the way results of the ab initio calculations should then be compared with experimental data.

Collision–induced absorption in gaseous methane at low temperatures

1986 ◽  
Vol 64 (7) ◽  
pp. 763-767 ◽  
Author(s):  
I. R. Dagg ◽  
A. Anderson ◽  
S. Yan ◽  
W. Smith ◽  
C. G. Joslin ◽  
...  
Keyword(s):  
Experimental Data ◽  
Low Temperatures ◽  
Low Frequency ◽  
Frequency Region ◽  
Experimental Results ◽  
Published Data ◽  
Frequency Range ◽  
Simple Method ◽  
Induced Absorption ◽  
Good Agreement

A recently developed theory for collision-induced absorption in methane is compared with experimental results over a wider spectral range and at lower temperatures than previously reported. The present experimental results covering the frequency range below 400 cm−1 exhibit good agreement with other recently published data. The theory shows excellent agreement with experiment in the low-frequency region below approximately 200 cm−1 but underestimates the experimental data somewhat at higher frequencies. Possible theoretical reasons for this discrepancy are given. The theory represents a simple method of obtaining a good estimate of the collision-induced absorption spectra of methane in this frequency region and for extrapolating to lower temperatures for which experimentation is not feasible. In addition, the moments α1 and γ1are compared with earlier determinations and indicate good agreement with the previously obtained values for the octupole and hexadecapole moments of methane.

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.

The magnitude of the anharmonic contribution to the static dielectric constant

1961 ◽  
Vol 261 (1305) ◽  
pp. 274-280 ◽  
Keyword(s):  
Dielectric Constant ◽  
Debye Temperature ◽  
Alkali Halides ◽  
Static Dielectric Constant ◽  
Ionic Crystals ◽  
Lattice Contribution ◽  
Temperature And Pressure ◽  
Derivatives Of

It is shown that in ionic crystals the anharmonic contribution to the static dielectric constant can be calculated above the Debye temperature if the derivatives of the dielectric constant with respect to temperature and pressure are known. The necessary data are available for three alkali halides. For these, the anharmonic contribution is found to amount to a few parts per cent of the total lattice contribution.

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.

THERMAL EXPANSION OF SINGLE CRYSTALS OF ZINC AT LOW TEMPERATURES

1965 ◽  
Vol 43 (7) ◽  
pp. 1328-1333 ◽  
Author(s):  
D. A. Channing ◽  
S. Weintroub
Keyword(s):  
Experimental Data ◽  
Thermal Expansion ◽  
Single Crystals ◽  
Low Temperatures ◽  
Linear Thermal Expansion ◽  
Optical Interference ◽  
Temperature Range ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Good Agreement

The linear thermal expansion coefficients αψ of two single crystals of Zn of orientations ψ = 10.8° and 63.9 ° with the hexad axis were measured over the temperature range of about 20–270 °K using an absolute Fizeau optical interference technique. The two principal coefficients, [Formula: see text] and [Formula: see text], corresponding to ψ = 0° and 90 ° respectively, were calculated from the Voigt relation, and their values are compared with previously reported experimental data. Above 60 °K there is good agreement with previous work, and below 60 °K the results confirm, in general, the data obtained by McCammon and White. The Grüneisen parameter γ is essentially constant at about 2.1 in the range 100–270 °K, but below 100 °K γ rises appreciably with decreasing temperature and reaches the value of about 3.5 at 20 °K.

The anharmonic attenuation of surface waves on crystals at low temperatures

1970 ◽  
Vol 320 (1541) ◽  
pp. 175-186 ◽  
Keyword(s):  
Experimental Data ◽  
Surface Wave ◽  
Surface Waves ◽  
General Formula ◽  
Attenuation Coefficient ◽  
Transverse Wave ◽  
Low Temperatures ◽  
Simplified Model ◽  
Integral Expression ◽  
Good Agreement

A general formula for the attenuation of a surface wave by interaction with thermal phonons at low temperatures is given and compared with the results of Maradudin & Mills (1968) for a simplified model. It is argued that the attenuation coefficient will often be qualitatively similar to that of the slow transverse wave propagating in the same direction. Approximations to our integral expression for the attenuation coefficient are discussed and numerical calculations for quartz described in detail. Good agreement with the experimental data of Salzmann, Plieninger & Dransfeld (1968) is obtained.

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