The Entropy and Low Temperature Heat Capacity of Neptunium Dioxide
Open Access
- 1 March 1953
- journal article
- research article
- Published by AIP Publishing in The Journal of Chemical Physics
- Vol. 21 (3), 419-423
- https://doi.org/10.1063/1.1698923
Abstract
The heat capacity of a two‐gram sample of neptunium dioxide was determined from 10 to 315°K in an adiabatic calorimeter. At 298.16°K the molal entropy and enthalpy calculated from the heat capacity data are 19.19±0.1 cal deg−1 and 2770±15 cal, respectively. A pronounced hump was found in the heat capacity curve of neptunium dioxide at 25.3°K similar to that found by Jones, Gordon, and Long in uranium dioxide at 28.7°K. This anomaly in the heat capacity is suggestive of a cooperative phenomenon and is attributed to the incidence of antiferromagnetism below the temperature of the maximum in the heat capacity. A calorimeter for gram scale samples and a modification of the cryostat design of Ruehrwein and Huffman so as to employ only liquid helium and liquid nitrogen as refrigerants are described.Keywords
This publication has 9 references indexed in Scilit:
- The Heat Capacities of Uranium, Uranium Trioxide, and Uranium Dioxide from 15°K to 300°KThe Journal of Chemical Physics, 1952
- The International Temperature Scale of 1948Journal of Research of the National Bureau of Standards, 1949
- The First Isolation of Element 93 in Pure Compounds and a Determination of the Half-life of 93Np237Journal of the American Chemical Society, 1948
- Low-temperature Calorimetry at the Bartlesville Station of the Bureau of Mines.Chemical Reviews, 1947
- Thermal Data. XVII. The Heat Capacity, Entropy, and Free Energy of Formation of Cyclohexane. A New Method of Heat Transfer in Low Temperature CalorimetryJournal of the American Chemical Society, 1943
- Specific Heats at Low Temperatures of Manganese Carbide and Manganese Dioxide1Journal of the American Chemical Society, 1943
- Magnetism and the Third Law of Thermodynamics. The Heat Capacity of Manganous Fluoride from 13 to 320°K.Journal of the American Chemical Society, 1942
- Further measurements of the magnetic properties of some salts of the iron group at low temperaturesPhysica, 1940
- Establishment of a temperature scale for the calibration of thermometers between 14 degrees and 83 degrees KJournal of Research of the National Bureau of Standards, 1939