FIRST SOUND IN LIQUID HELIUM AT HIGH PRESSURES

1953 ◽  
Vol 31 (7) ◽  
pp. 1156-1164 ◽  
Author(s):  
K. R. Atkins ◽  
R. A. Stasior
Keyword(s):  
Specific Heat ◽  
Liquid Helium ◽  
Carrier Frequency ◽  
High Pressures ◽  
Constant Pressure ◽  
Constant Density ◽  
Pulse Technique ◽  
Temperature Range ◽  
Specific Heats ◽  
First Sound

The velocity of ordinary sound in liquid helium has been measured in the temperature range from 1.2 °K. to 4.2 °K. at pressures up to 69 atm. A pulse technique was used with a carrier frequency of 12 Mc.p.s. Curves are given for the variation of velocity with temperature at constant pressure and also at constant density. There is no detectable discontinuity along the λ-curve. The results are used to discuss the ratio of the specific heats, the coefficient of expansion below 0.6 °K., and the specific heat above 3 °K.

Specific heats of polymer powders by differential scanning calorimetry

1982 ◽  
Vol 60 (14) ◽  
pp. 1853-1856 ◽  
Author(s):  
Eva I. Vargha-Butler ◽  
A. Wilhelm Neumann ◽  
Hassan A. Hamza
Keyword(s):  
Differential Scanning Calorimetry ◽  
Specific Heat ◽  
Scanning Calorimetry ◽  
Temperature Range ◽  
Specific Heats ◽  
Powdered Form ◽  
Polymer Powders

The specific heats of five polymers were determined by differential scanning calorimetry (DSC) in the temperature range of 300 to 360 K. The measurements were performed with polymers in the form of films, powders, and granules to clarify whether or not DSC specific heat values are dependent on the diminution of the sample. It was found that the specific heats for the bulk and powdered form of the polymer samples are indistinguishable within the error limits, justifying the determination of specific heats of powders by means of DSC.

Specific heats of plutonium and neptunium

1970 ◽  
Vol 317 (1530) ◽  
pp. 303-317 ◽  
Keyword(s):  
Specific Heat ◽  
Smooth Function ◽  
Magnetic Ordering ◽  
Temperature Range ◽  
Specific Heats ◽  
Very High

The specific heats of plutonium and neptunium metal have been measured from 13 and 7.5 K respectively, to 300 K. Both metals have very high electronic specific heats of 15.9 and 14.2 mJ mol -1 K -2 . A small anomaly in plutonium at about 60 K was found and is possibly caused by magnetic ordering. The specific heat of neptunium is a smooth function over the whole temperature range.

Properties of a Lattice Gas Model for 3He–4He Mixtures II: Analysis of High Temperature Series for the f.c.c. Lattice

1975 ◽  
Vol 53 (10) ◽  
pp. 987-1002 ◽  
Author(s):  
M. Plischke ◽  
D. D. Betts
Keyword(s):  
High Temperature ◽  
Specific Heat ◽  
Lattice Gas ◽  
Chemical Potential ◽  
Constant Pressure ◽  
Temperature Series ◽  
Adjustable Parameter ◽  
Constant Density ◽  
Constant Concentration ◽  
Chemical Potential Difference

For the Cheng–Schick model of 3He–4He mixtures high temperature series expansions at (a) constant density and constant concentration and (b) constant pressure and constant chemical potential difference are presented for the f.c.c. lattice for the fluctuation in the superfluid order parameter, the concentration susceptibility, and the specific heat at constant chemical potential. Analysis of the fluctuation series yields well defined lambda temperatures. In addition analysis of the concentration susceptibility series provides a less precise estimate of the tricritical concentration. The specific heat series have not proved very amenable to analysis. Upon fixing a single adjustable parameter the lambda curve of the model agrees precisely with experiment for all 3He concentrations. Estimates of tricritical exponents could not be obtained.

THE SPECIFIC HEAT OF MANGANESE FROM 16° TO 22° K

1940 ◽  
Vol 18a (5) ◽  
pp. 83-89 ◽  
Author(s):  
R. G. Elson ◽  
H. Grayson Smith ◽  
J. O. Wilhelm
Keyword(s):  
Specific Heat ◽  
Liquid Helium ◽  
Temperature Region ◽  
Liquid Hydrogen ◽  
Specific Heats ◽  
Atomic Heat

A calorimeter is described for routine measurements of specific heats in the temperature region of liquid hydrogen and liquid helium. It is designed so that samples can be interchanged without disturbing the calibration of the thermometer, or the water equivalent of the calorimeter. The calorimeter has been used to measure the specific heat of manganese from 16° to 22° K. It was found that the atomic heat of this metal is given by the formula[Formula: see text]

scholarly journals The specific heats of air and carbon dioxide at atmospheric pressure, by the continuous electrical method, at 20° C. and at 100° C

1909 ◽  
Vol 82 (553) ◽  
pp. 147-149 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Specific Heat ◽  
Electric Current ◽  
Atmospheric Pressure ◽  
Constant Pressure ◽  
Elementary Theory ◽  
Electrical Method ◽  
Specific Heats ◽  
Platinum Coil ◽  
A Current

A steady stream of gas was passed through a jacketed tube (the calorimeter proper), in which it was heated by a current of electricity passing through a platinum coil of 1 ohm resistance, the rise in temperature being measured by two 12-ohm platinum thermometers used differentially. If C is the electric current, E the potential difference between the ends of the heating coil, δθ the rise in temperature of the gas, Q the rate of flow of the gas in grammes per second, J the mechanical equivalent of heat, and S the specific heat of the gas at constant pressure, the elementary theory of the experiment gives CE = JSQ δθ + h δθ .

Brillouin Scattering in Liquid Benzene Under High Pressure

1983 ◽  
Vol 38 (9) ◽  
pp. 980-986
Author(s):  
A. Asenbaum ◽  
H. D. Hochheimer
Keyword(s):  
Specific Heat ◽  
High Pressures ◽  
Cell Model ◽  
Transport Coefficients ◽  
Energy Relaxation ◽  
Constant Density ◽  
Sphere Diameter ◽  
Vibrational Modes ◽  
Relaxation Rates ◽  
Liquid Benzene

Abstract Brillouin spectra have been measured in liquid Benzene at high pressures up to 1300 bar and at the temperatures 298.15 K, 313.15 K, 323.15 K. and 343.15 K. From the experimental spectra the hypersound velocities and the energy relaxation times were determined. The total velocity dispersion ν2∞/ν20 due to the relaxation of the vibrational specific heat c, is found to be nearly density independent in the pressure interval under study. It follows further that the experimentally determined specific heat corresponds to the theoretical value calculated with the vibrational modes of the Benzene molecule. The energy relaxation time t, connected with all vibrational modes but the lowest decreases with increasing density at constant temperature, at constant density τ1 decreases with growing temperature. The relative relaxation rates were used to test the cell model (CM) with movable walls and the collision theory (HS) of Einwohner and Alder. Using a hard sphere diameter derived from ex-perimental transport coefficients the experimental results were predicted better by HS than by CM.

Crystal Dynamics and Electronic Specific Heats of Palladium and Copper

1971 ◽  
Vol 49 (6) ◽  
pp. 704-723 ◽  
Author(s):  
A. P. Miiller ◽  
B. N. Brockhouse
Keyword(s):  
Specific Heat ◽  
Room Temperature ◽  
Constant Pressure ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Frequency Wave ◽  
Frequency Distributions ◽  
Specific Heats ◽  
Lattice Specific Heat ◽  
Crystal Dynamics

Using inelastic neutron scattering, the frequency – wave vector dispersion relations for the lattice vibrations in a single crystal of palladium have been determined at 120, 296, 673, and 853 °K. Analyses of the results have given force-constant models from which frequency distributions have been computed. First-neighbor interactions are dominant, but weaker interactions also exist, extending beyond sixth-nearest neighbors. The total lattice specific heat (harmonic plus anharmonic) at constant pressure has been calculated, using the frequency distribution at 296 °K and the shifts in the frequencies with changing temperature. Similar calculations were also carried out for copper, using the room temperature distribution reported by Svensson et al.; the temperature dependence of the frequencies was established by carrying out measurements along major symmetry directions of Cu at 296, 473, and 673 °K. The electronic specific heats of Cu and Pd have been calculated at temperatures between 0 and 900 °K. The electronic specific heat of Cu agrees well enough with the linear relation Ce = γT for T < 700 °K. For Pd, Ce is anomalously high at low temperatures, in agreement with experiments at helium temperature, but tends to saturate for temperatures > 200 °K.

scholarly journals Velocity of sound in liquid argon at high pressures and temperatures

1968 ◽  
Vol 46 (8) ◽  
pp. 1175-1180 ◽  
Author(s):  
D. H. Bowman ◽  
C. C. Lim ◽  
R. A. Aziz
Keyword(s):  
Specific Heat ◽  
High Pressures ◽  
Constant Pressure ◽  
Liquid Argon ◽  
Velocity Versus ◽  
Velocity Of Sound ◽  
Temperature Analysis ◽  
Density Data ◽  
Specific Heat Ratio ◽  
High Pressures And Temperatures

Measurements were made of the velocity of sound in liquid argon in the temperature range 86–146 °K and at pressures up to 65 atm. The velocity versus pressure isotherms are steeper and more curved at the higher temperatures. At any one pressure, the velocity is a smoothly decreasing function of temperature. Analysis of the results using existing density data showed that the specific heat ratio, γ, decreases with pressure and increases with temperature in this range. The coefficient in Rao's relation was found to increase with temperature at constant pressure, while that in the relation due to Carnevale and Litovitz exhibited no definite trend with temperature or pressure.

Sign in / Sign up

Export Citation Format

Share Document