The nuclear specific heat in paramagnetic cupric salts at temperatures below 1° K I. Thermodynamic measurements made from a study of the field-dependence of the adiabatic susceptibility

1950 ◽  
Vol 203 (1074) ◽  
pp. 375-391 ◽  
Keyword(s):  
Magnetic Susceptibility ◽  
Specific Heat ◽  
Field Dependence ◽  
Absolute Temperature ◽  
Potassium Sulphate ◽  
Specific Heats ◽  
Magnetic Cooling ◽  
Thermodynamic Measurements ◽  
Small Fields ◽  
The Absolute

Thermodynamic measurements have been made at temperatures below 1°K, obtained by the method of magnetic cooling, on copper potassium sulphate and on a diluted copper Tutton salt. A study has been made of the field- dependence (for small fields) of the adiabatic susceptibility of the cooled and thermally isolated salt, the measurements covering the range of temperature from 1°K down to 0.05°K for copper potassium sulphate, and to 0.025° K for the dilute salt. From these measurements the entropy and magnetic susceptibility are determined as functions of the absolute temperature. It is concluded that for both salts the susceptibility follows a Curie-Weiss law, the values of ∆ being 0.034 and 0.0048º K respectively; the specific heats are of the form ∆ / T 2 , the values found for A being 6.1x10 -4 R for copper potassium sulphate and 1.98x10 -4 R for the dilute salt.Deviations from this behaviour in a ferromagnetic direction are found for copper potassium sulphate below 0.07° K.

The specific heats of three paramagnetic salts at very low temperatures

1956 ◽  
Vol 237 (1210) ◽  
pp. 395-403 ◽  
Keyword(s):  
Specific Heat ◽  
Absolute Temperature ◽  
Magnesium Nitrate ◽  
Paramagnetic Resonance ◽  
Specific Heats ◽  
Ammonium Alum ◽  
Relaxation Measurements ◽  
Ferric Ammonium ◽  
The Absolute ◽  
Measured Specific Heat

The specific heats of three paramagnetic salts, neodymium magnesium nitrate, manganous ammonium sulphate and ferric ammonium alum, have been measured at temperatures below 1°K using the method of γ -ray heating. The temperature measurements were made in the first instance in terms of the magnetic susceptibilities of the salts, the relation of the susceptibility to the absolute temperature having been determined for each salt in earlier experiments. The γ -ray heatings gave the specific heat in arbitrary units. The absolute values of the specific heats were found by extrapolating the results of paramagnetic relaxation measurements at higher temperatures. The measured specific heat of neodymium magnesium nitrate is compared with the value calculated from paramagnetic resonance data, and good agreement is found.

Temperature-dependent Specific Heats of Dry Soil Materials

1975 ◽  
Vol 12 (2) ◽  
pp. 209-212 ◽  
Author(s):  
B. D. Kay ◽  
J. B. Goit
Keyword(s):  
Specific Heat ◽  
Functional Relation ◽  
Absolute Temperature ◽  
Temperature Dependent ◽  
Specific Heats ◽  
Proportionality Constant ◽  
Single Temperature ◽  
Different Temperatures ◽  
Dry Soil ◽  
The Absolute

Specific heat measurements have been made on several soil materials at different temperatures in order to obtain a generalized functional relation between specific heat and temperature. Specific heats were found to vary linearly with temperature from 200 to 300 °K (−73 °C to + 27 °C) and extrapolated close to zero at 0 °K. Consequently, the functional relation between specific heat and temperature for soil materials may be approximated as Cp = mT where Cp is the specific heat, T is the absolute temperature (°K), and m is a proportionality constant. Such a relation permits the prediction of the specific heats at any temperature normally encountered in the field once reliable specific heats have been determined at a single temperature.

Thermal and magnetic properties of ferric methylammonium sulphate

1956 ◽  
Vol 237 (1210) ◽  
pp. 404-412 ◽  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Specific Heat ◽  
Magnetic Anomaly ◽  
Ground State ◽  
Magnetic Contribution ◽  
Lattice Contribution ◽  
Magnetic Cooling ◽  
Maximum Value ◽  
Other Substances

The specific heat and magnetic susceptibility of ferric methylammonium sulphate have been measured at temperatures between 0·17 and 20°K. The specific heat has been analyzed into a lattice contribution and a magnetic anomaly. It is shown that the magnetic contribution to the specific heat can be accounted for almost entirely by the Schottky anomaly due to the Stark splittings of the ground state of the Fe 3+ ions, previously determined by Bleaney & Trenam. These splittings are unusually large in this salt, with the result that the specific heat is very large at temperatures near 1°K, reaching a maximum value of 1·1 cal/mole at 0·33°K. The salt should therefore be useful for magnetic cooling experiments in which other substances are to be kept below 1°K for prolonged periods.

Rotational Specific Heat and Rotational Entropy of Simple Gases at Moderate Temperatures

1930 ◽  
Vol 26 (3) ◽  
pp. 402-418 ◽  
Author(s):  
G. B. B. M. Sutherland
Keyword(s):  
Specific Heat ◽  
Absolute Temperature ◽  
Moment Of Inertia ◽  
Planck’S Constant ◽  
Diatomic Gas ◽  
The Absolute ◽  
The Moment ◽  
Image Position ◽  
Planck's Constant

It is well known that the rotational specific heat of a diatomic gas is given bywhere R is the gas constant, σ = h2/8π2AKT, h is Planck's constant, T is the absolute temperature, K is Boltzmann's constant, and A is the moment of inertia of the molecule.

scholarly journals III. On the specific heats of gases at constant volume. Part I. Air, carbon dioxide, and hydrogen

1891 ◽  
Vol 48 (292-295) ◽  
pp. 440-441 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Specific Heat ◽  
Mean Value ◽  
Constant Volume ◽  
Specific Heats ◽  
Absolute Density ◽  
The Mean ◽  
The Absolute

In this first notice the specific heats, at constant volumes, of air, carbon dioxide, and hydrogen are treated over pressures ranging from 7 to 25 atmospheres. The range of temperature is not sensibly varied. It is found that the specific heats of these gases are not constant, but are variable with the density. In the case of air the departure from constancy is small and positive; that is, the specific heat increases with increase of the density. The experiments afford directly the mean value 0·1721 for the specific heat of air at the absolute density of 0·0205, corresponding to the pressure of 19·51 atmospheres. A formula based on the variation of the specific heat with density observed in the experiments ascribes the value 0·1715 for the specific heat at the pressure of one atmosphere.

Thermal properties of potassium chromic alum between 0.05 and 1°K

1950 ◽  
Vol 204 (1077) ◽  
pp. 216-223 ◽  
Keyword(s):  
Thermal Properties ◽  
Specific Heat ◽  
Preceding Paper ◽  
Absolute Temperature ◽  
Paramagnetic Resonance ◽  
The Absolute

The entropy, specific heat and magnetic temperature (reciprocal of the susceptibility) of potassium chromic alum are measured as functions of the absolute temperature between 0.05 and 1° K. Their interpretation in the light of paramagnetic resonance measurements (preceding paper) is discussed.

scholarly journals The ratio of the specific heats of nitrogen and of oxygen

1924 ◽  
Vol 105 (730) ◽  
pp. 225-243 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Large Volume ◽  
Ideal Gas ◽  
Absolute Temperature ◽  
Specific Heats ◽  
Previous Communication ◽  
Free Air ◽  
Before And After ◽  
The Absolute

The investigation of the ratio of the specific heats, c p / c v = γ , of nitrogen and oxygen described in the following paper was undertaken by a method substantially the same as that used previously with air and carbon dioxide, and described in an earlier communication. This consists in measuring the fall in temperature which occurs when a large volume of the gas is allowed to expand adiabatically. If a vessel filled with the gas at a pressure p 1 , slightly greater than atmospheric, is put into communication with the free air, at a pressure p 2 , by suitable means, so that the equalisation of pressures occurs as nearly as possible adiabatically, and if T 1 and T 2 are the absolute temperature of the gas before and after expansion, then, for an ideal gas , it is known that γ = c p /c v = log p 1 - log p 2 /(log p 1 - log p 2 ) - (log T 1 - log T 2 ) (1) Before considering the details of the method used in the present research reference may be made to the experiments of Mercer, in 1914, and of Shields, in 1917, supplementing the work discussed in the previous communication.

ON THE SPECIFIC HEATS OF TUNGSTEN, MOLYBDENUM, AND COPPER

1933 ◽  
Vol 8 (3) ◽  
pp. 282-303 ◽  
Author(s):  
H. L. Bronson ◽  
H. M. Chisholm ◽  
S. M. Dockerty
Keyword(s):  
Specific Heat ◽  
Linear Equations ◽  
Adiabatic Calorimeter ◽  
Absolute Temperature ◽  
Large Temperature ◽  
Average Deviation ◽  
Specific Heats ◽  
New Type ◽  
The Individual ◽  
Theoretical Considerations

This paper contains the results of a long series of determinations of the specific heats of tungsten, molybdenum, and copper from − 20° to 500 °C.A new type of all-copper adiabatic calorimeter has been designed and used. The complete elimination of water from the calorimeter removed several sources of error and resulted in increased reliability and accuracy.Two entirely different methods were used in determining the specific heats. The usual "method of mixtures" was used to determine the mean specific heat for a large temperature change and was applied to all three metals over the entire range of temperature. The specific heat of copper was also determined for 5- or 10-degree intervals from − 5° to 110 °C. by heating the calorimeter electrically.It has been quite definitely shown that the specific heats of these metals over a temperature range as large as 0° to 500 °C. cannot be expressed as a linear function of the temperature. An equation of the form Cp = A + BT − C/T2 was arrived at from theoretical considerations and the constants determined empirically with the following results:—[Formula: see text]where the unit of heat is the 20-degree calorie and T is absolute temperature. The average deviation of the individual determinations from the values calculated by these equations was only about 0.1%.As a matter of convenience and for purposes of comparison, linear equations applicable over smaller ranges of temperature have also been given.

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