Enthalpy and Heat-Capacity Standard Reference Material: Synthetic Sapphire (α-Al₂O₃) from 10 to 2250 K.

Area of Science:

• Materials Science
• Thermodynamics
• Physical Chemistry

Background:

• NBS SRM 720 (α-Al2O3) is a critical standard for heat capacity and enthalpy measurements.
• Accurate thermodynamic data is essential for materials characterization and industrial applications.

Purpose of the Study:

• To present previously unpublished high-temperature enthalpy data for α-Al2O3.
• To provide smoothed and revised thermodynamic data for NBS SRM 720.
• To establish reliable enthalpy and heat capacity values across a wide temperature range.

Main Methods:

• High-temperature experimental measurements.
• Least-squares spline technique for data smoothing.
• Analysis of low-temperature measurements from the National Bureau of Standards (NBS).

Main Results:

• Publication of new, unpublished enthalpy data for α-Al2O3.
• Generation of smooth enthalpy and heat capacity data.
• A revised table of certified values for α-Al2O3 from 10 K to 2250 K.

Conclusions:

• The study provides a comprehensive and accurate thermodynamic dataset for α-Al2O3.
• The revised data enhances the reliability of NBS SRM 720 as a standard.
• This work supports precise thermodynamic calculations and material property assessments.