Dislocation relaxation in tantalum at low temperatures

1968 ◽  
Vol 46 (23) ◽  
pp. 2715-2717 ◽  
Author(s):  
L. Verdini ◽  
L. A. Vienneau
Keyword(s):  
Vibration Frequency ◽  
Low Temperatures ◽  
Permanent Deformation ◽  
Relaxation Times ◽  
Dislocation Motion ◽  
Temperature Curve ◽  
Peierls Stress ◽  
Characteristic Parameters ◽  
Thermally Activated ◽  
A Value

A maximum in the dissipation vs. temperature curve has been observed at about 25 °K in tantalum after a permanent deformation of about 7%. The temperature of the maximum increases with the vibration frequency indicating the presence of a thermally activated relaxation process. This effect is attributed to the dislocation motion (Bordoni peak) and the characteristic parameters are W = 0.038 eV and [Formula: see text]. Using the Seeger equation, a value for the Peierls' stress of about 6.5 × 106 dyn cm−2 is found. The presence of a large spectrum of relaxation times is also discussed.

DISLOCATION MOTION AT LOW TEMPERATURES

1988 ◽  
Vol 49 (C3) ◽  
pp. C3-673-C3-676
Author(s):  
J. M. GALLIGAN ◽  
C. S. KIM ◽  
K. BRIGGS ◽  
Y. CORDON
Keyword(s):  
Low Temperatures ◽  
Dislocation Motion

scholarly journals Theoretical Effect of Temperature on Threshold in the Hodgkin-Huxley Nerve Model

1966 ◽  
Vol 49 (5) ◽  
pp. 989-1005 ◽  
Author(s):  
Richard Fitzhugh
Keyword(s):  
Relaxation Time ◽  
Relaxation Times ◽  
Giant Axon ◽  
Temperature Curve ◽  
Effect Of Temperature ◽  
Threshold Temperature ◽  
Ionic Conductances ◽  
And Shifts ◽  
The Right ◽  
Increasing Temperature

In the squid giant axon, Sjodin and Mullins (1958), using 1 msec duration pulses, found a decrease of threshold with increasing temperature, while Guttman (1962), using 100 msec pulses, found an increase. Both results are qualitatively predicted by the Hodgkin-Huxley model. The threshold vs. temperature curve varies so much with the assumptions made regarding the temperature-dependence of the membrane ionic conductances that quantitative comparison between theory and experiment is not yet possible. For very short pulses, increasing temperature has two effects. (1) At lower temperatures the decrease of relaxation time of Na activation (m) relative to the electrical (RC) relaxation time favors excitation and decreases threshold. (2) For higher temperatures, effect (1) saturates, but the decreasing relaxation times of Na inactivation (h) and K activation (n) factor accommodation and increased threshold. The result is a U-shaped threshold temperature curve. R. Guttman has obtained such U-shaped curves for 50 µsec pulses. Assuming higher ionic conductances decreases the electrical relaxation time and shifts the curve to the right along the temperature axis. Making the conductances increase with temperature flattens the curve. Using very long pulses favors effect (2) over (1) and makes threshold increase monotonically with temperature.

Dislocation motion in pure NaCl at low temperatures

1972 ◽  
Vol 25 (5) ◽  
pp. 1073-1094 ◽  
Author(s):  
A. S. Argon ◽  
G. E. Padawer
Keyword(s):  
Low Temperatures ◽  
Dislocation Motion

scholarly journals THE EFFECT OF POLYANILINE CONTENT DEPOSITED ON SILICA GEL PARTICLES ON THE ELECTRORHEOLOGY OF SILICONE-OIL SUSPENSIONS

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1097-1103 ◽  
Author(s):  
V. PAVLÍNEK ◽  
P. SÁHA ◽  
T. KITANO ◽  
J. HROMÁDKOVÁ ◽  
J. STEJSKAL ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Silicone Oil ◽  
Relaxation Times ◽  
Content Volume ◽  
Interfacial Polarization ◽  
Secondary Importance ◽  
Frequency Spectra ◽  
Pure Silica ◽  
A Value ◽  
Dc Electric Field

Investigation of the electrorheological effect of silicone-oil suspensions of silica particles coated with polyaniline base in a DC electric field revealed that breaking stress, as a criterion the intensity of the electrorheological phenomenon, steeply increased at first with coating thickness. At relatively low polyaniline content (volume fraction ≈ 0.05), it has reached a value several times higher than that with suspension of pure silica. Then they became virtually constant or slightly increased. The frequency spectra of dielectric characteristics of these systems reflect high relaxation times. The results suggest that the interfacial polarization of particles is predominantly controlled by polarizability of their surface layer, and the influence of the thickness is of secondary importance.

scholarly journals The chemical constant of hydrogen vapour and the entropy of crystalline hydrogen

1931 ◽  
Vol 130 (813) ◽  
pp. 367-379 ◽  
Keyword(s):  
Vapour Pressure ◽  
Low Temperatures ◽  
Hydrogen Gas ◽  
Para Hydrogen ◽  
Bose Statistics ◽  
Hydrogen Molecules ◽  
Quantum Numbers ◽  
A Value ◽  
Classical Statistics ◽  
Chemical Constant

In a paper called "The Chemical constant of Hydrogen Vapour and the failure of Nernst's Heat Theorem," R. H. Fowler has investigated the vapour pressure of hydrogen crystals at low temperature; taking account of the existence of two sorts of hydrogen molecules, namely, ortho-hydrogen with even rotational quantum numbers and para-hydrogen with odd rotational quantum numbers, which retain their individuality over long periods at very low temperatures. By the use of the classical statistics, he was able to show that at very low temperatures hydrogen, as obtained by cooling hydrogen gas from ordinary temperatures, ought to have very nearly the experimentally observed chemical constant. Since the theory of the specific heat of hydrogen yielded correct values at low temperatures, it followed that at ordinary temperatures also his theory would yield a correct value for the chemical constant. Finally from the form of the partition function for hydrogen gas, Fowler attempted to obtain inferences concerning the validity of Nernst's heat theorem. By the use of the classical statistics fairly accurate results were obtained. But we shall find that when we make use of the Einstein-Bose statistics-the correct statistics for an assembly of hydrogen moleclues-a result will be obtained for the vapour pressure of hydrogen crystals at low temperatures which will furnish a value for the chemical constant of hydrogen in even closer agreement with experiment than Fowler's result.

Thermally activated flow of H.C.P. metals at low temperatures

1976 ◽  
Vol 33 (1) ◽  
pp. 173-187 ◽  
Author(s):  
D. H. Sastry ◽  
M. J. Luton ◽  
J. J. Jonas
Keyword(s):  
Low Temperatures ◽  
Thermally Activated

Nuclear spin-lattice relaxation times of metallic antimony at low temperatures

1995 ◽  
Vol 101 (3-4) ◽  
pp. 611-615 ◽  
Author(s):  
E. B. Genio ◽  
J. Xu ◽  
T. Lang ◽  
G. G. Ihas ◽  
N. S. Sullivan
Keyword(s):  
Nuclear Spin ◽  
Low Temperatures ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Nuclear Spin Lattice Relaxation

Specific Heat of the Synthetic Rubber Hycar-OR from 15° to 340° K

1943 ◽  
Vol 16 (2) ◽  
pp. 310-317 ◽  
Author(s):  
Norman Bekkedahl ◽  
Russell B. Scott
Keyword(s):  
Heat Equation ◽  
Specific Heat ◽  
Temperature Curve ◽  
Second Order ◽  
Heat Temperature ◽  
A Value ◽  
Synthetic Rubber ◽  
Experimental Values ◽  
Adiabatic Vacuum

Abstract Measurements of specific heat were made on a sample of Hycar-OR synthetic rubber from 15° to 340° K by means of an adiabatic vacuum-type calorimeter. The experimental values of the specific heat between 15° and 22° K were well represented by the Debye specific-heat equation, using a βν value of 80 and, accordingly, the values below 15° K were calculated with this equation. At about 250° K the material has a transition of the second order, the specific heat increasing by about 40 per cent to a value of 1.84 Int. joules · gram−1 · degree−1 just above the transition. From 250° to 340° K the specific heat-temperature curve is nearly linear, and the values can be calculated to within 0.2 per cent from the formula Cp=0.00283T+1.126, in Int. joules · gram−1 · degree−1. At 298.16° K (25° C) the specific heat is 1.971 Int. joules · gram−1 · degree−1 (0.4712 calories · gram−1 · degree−1). The increase in entropy resulting from heating from 0° to 298.16° K was calculated to be 1.743 ± 0.002 Int. joules · gram−1 · degree−1 (0.4167 ± 0.0005 calories · gram−1 · degree−1).

Study of Rheological Properties of Cariphalte Modified Asphalt

2014 ◽  
Vol 638-640 ◽  
pp. 1185-1189
Author(s):  
Tan Hua
Keyword(s):  
Comparative Analysis ◽  
Rheological Properties ◽  
Fatigue Damage ◽  
Systematic Study ◽  
Low Temperatures ◽  
Permanent Deformation ◽  
Asphalt Binder ◽  
Fatigue Properties ◽  
Dynamic Shear ◽  
Modified Asphalt

To explore the effects of different factors on the rheological properties of cariphalte modified asphalt, based superpave asphalt binder relevant norms, through the use of dynamic shear rheometer Shell 70# asphalt under different temperature, frequency and strain conditions and rheological properties of cariphalte modified asphalt carrying on a systematic study, and comparative analysis of the two anti-fatigue properties of asphalt in the middle and low temperature.The results show that: compared with 70# asphalt, cariphalte modified asphalt has better rutting resistance over a wide temperature range; at lower frequencies and high intensity pavement, cariphalte modified asphalt to better resistance to permanent deformation; better fatigue resistance at low temperatures, and more fatigue damage is not easy to achieve.

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