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Thermodynamic temperature assignment to the point of inflection of the melting curve of high-temperature fixed points



Howard W. Yoon, John T. Woodward IV, E. R. Woolliams, Joaquin Campos-Acosta


The thermodynamic temperature of the point of inflection of the melting transition of Re-C, Pt-C and Co-C eutectics has been determined to be 2747.84±0.35 K, 2011.43±0.18K and 1597.39±0.13 K, respectively, and the thermodynamic temperature of the freezing transition of Cu has been determined to be 1357.80±0.08 K, where the ± symbol represents 95% coverage. These results are the best consensus estimates obtained from measurements made using various spectroradiometric primary thermometry techniques by nine different national metrology institutes. The good agreement between the institutes suggests that spectroradiometric thermometry techniques are sufficiently mature (at least in those institutes) to allow the direct realization of thermodynamic temperature above 1234K (rather than the use of a temperature scale) and that metal-carbon eutectics can be used as high-temperature fixed points for thermodynamic temperature dissemination. The results directly support the developing mise en pratique for the definition of the kelvin to include direct measurement of thermodynamic temperature.
Philosophical Transactions of the Royal Society A-Mathematical Physical and Engineering Sciences


high-temperature fixed points, thermodynamic temperature, thermometry, temperature scale, kelvin, eutectics
Created March 28, 2016, Updated November 10, 2018