Ne
Ne provides ideal gas thermodynamic properties for neon valid over the temperature range from 200 K to 6000 K based on the property information in McBride et al. (2002).
Bonnie J. McBride, Michael J. Zehe, and Sanford Gordon
"NASA Glenn Coefficients for Calculating Thermodynamic Properties of Individual Species"
NASA/TP-2002-211556, Sept. 2002
https://www.grc.nasa.gov/WWW/CEAWeb/
The reference state for specific enthalpy is 0 at 25 C. The reference state for specific entropy is 146.323 kJ/kmol-K at 298.15 K and 101.3 kPa.
Thermal conductivity data are from:
"Reference Handbook of Thermal Conductivity of Liquids and Gases, Vargaftik et al., 1994, CRC Press
These data are provided in the range from 70 K to 5000 K.
Viscosity data are from:
"Thermodynamic Properties of Refrigerants",
P.E. Liley and P.D. Desai, ASHRAE, ISBN 1-883413-10-9, 1993.
These data are provided in the range from 25 K to 1000 K
Note that Ne provides thermodynamic properties assuming ideal gas behavior. Use Neon to provide real fluid properties in the subcooled, saturated mixture, and superheated regimes.