Thermodynamics Research Center / ThermoML | International Journal of Thermophysics

Triple-Point Temperatures of 20Ne and 22Ne

hill, K. D., fahr, M.
Int. J. Thermophys. 2011, 32, 1-2, 173-188
ABSTRACT
Interest in the triple points of neon isotopes has recently arisen as a result of the multi-institute project to understand how variations in the isotopic composition of natural neon influence the triple-point temperature of a particular sample. Given the challenges in determining with sufficiently low uncertainty both the relative isotopic concentrations, particularly of 22Ne relative to 20Ne, and the temperature differences among cells filled from different gas sources in order to determine the sensitivity coefficient with adequate confidence, modeling of the isotopic influence becomes an attractive alternative for correcting the triple points of natural neon samples to a common composition. The modeling requires, among other things, knowledge of the triple-point temperatures of 20Ne and 22Ne. The triple points of these pure neon isotopes have utility in their own right as secondary reference temperatures on the ITS-90, and one or both of these could replace natural neon in a revised International Temperature Scale or approximation to the ITS. The neon isotope triple-point temperatures (on the IPTS-68) reported by Furukawa, Kemp, and Sakurai in various publications from 1972 to 1986 predate the ITS-90, and so there is utility in contemporary measurements (on the ITS-90) with gas samples of recent production. At NRC, we find the triple point of 20Ne to be at 24.54230 K (13.80 mK below the triple point of natural neon) and that of 22Ne to be at 24.68889 K (132.79 mK above the triple point of natural neon), assuming the reference sample of natural neon realizes the ideal ITS-90 temperature of 24.5561 K.
Compounds
# Formula Name
1 Ne neon-20
2 Ne neon-22
Datasets
The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type Compound-# Property Variable Constraint Phase Method #Points
  • POMD
  • 1
  • Triple point temperature, K ; Crystal
  • Crystal
  • Liquid
  • Gas
  • triple pt. cell
  • 1
  • POMD
  • 2
  • Triple point temperature, K ; Crystal
  • Crystal
  • Liquid
  • Gas
  • triple pt. cell
  • 1