Sublimation studies of NpO sub 2 F sub 2
- Nuclear Materials Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
- SRI International, Menlo Park, California 94025 (United States)
Using Knudsen effusion mass spectrometry, we have identified the following reaction as the sublimation decomposition mechanism of NpO{sub 2}F{sub 2}({ital s}): 2NpO{sub 2}F{sub 2}({ital s})=NpO{sub 2}({ital s})+O{sub 2}({ital g})+NpF{sub 4}({ital g}). From second-law analysis of the measured pressures of NpF{sub 4}({ital g}) over the temperature range 820--985 K the derived enthalpy change at 298 K is 556.8{plus minus}12.2 kJ/mol and the entropy change is 342.4 {plus minus}13.8 J/K mol. From these values and enthalpies of formation and entropies reported in the literature for the other species we calculate the enthalpy of formation of NpO{sub 2}F{sub 2}({ital s}) to be {minus}1608{plus minus}10 kJ/mol and the entropy to be 147{plus minus}9 J/K mol.
- OSTI ID:
- 7200669
- Journal Information:
- Journal of Chemical Physics; (United States), Vol. 97:4; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
NEPTUNIUM COMPOUNDS
SUBLIMATION
OXYFLUORIDES
DECOMPOSITION
ENTHALPY
KNUDSEN FLOW
MASS SPECTROSCOPY
STABILITY
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0400-1000 K
THERMODYNAMICS
ACTINIDE COMPOUNDS
CHEMICAL REACTIONS
EVAPORATION
FLUID FLOW
FLUORINE COMPOUNDS
GAS FLOW
HALOGEN COMPOUNDS
OXYGEN COMPOUNDS
OXYHALIDES
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
SPECTROSCOPY
TEMPERATURE RANGE
THERMODYNAMIC PROPERTIES
TRANSURANIUM COMPOUNDS
400702* - Radiochemistry & Nuclear Chemistry- Properties of Radioactive Materials
400800 - Combustion
Pyrolysis
& High-Temperature Chemistry