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

E. R. Woolliams et al. ; 23 págs.; 5 figs. 4 tabs.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 ± 0.18 K 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 1234 K (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. © 2016 The Author(s)National Physical Laboratory, Physikalisch-Technische Bundesanstalt, LCM LNE-Cnam, Spanish\udNational Research Council, Centro Español de Metrologia acknowledge funding from the European\udMetrology Research Programme (EMRP) through which the Implementing the new kelvin (INK) project was\udfunded. The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European\udUnion. National Institute of Metrology acknowledges the support from the National Key Technology Support\udProgram (no 2006BAF06B03) and the National Natural Science Foundation of China (no 51206151). A.D.W.T.\udand D.J.W. acknowledge funding by the National Research Council Canada. The All-Russian Research\udInstitute for Optical and Physical Measurements acknowledges funding from the Ministry of Education and\udScience of the Russian Federation (identification number RFMEFI59214X0001).Peer Reviewe