Intercomparison of the Realization of the ITS‐90 in the Temperature Range −40 °C to 420 °C between CENAM and PTB

A comparison of the realization of the temperature scale ITS‐90 was organized between PTB and CENAM in the range from −40 °C to 420 °C which includes the Hg, H₂O, Ga, In, Sn, and Zn fixed points. Measurements were carried out with two platinum resistance thermometers in different schemes. The results obtained with both thermometers coincide well within 0.5 mK for all fixed points except for the Zn freezing point, where the deviation between PTB and CENAM was 1.6 mK with one SPRT and 0.1 mK with the other SPRT. The difference observed between the two Zn measurements resembles results previously obtained during past international comparisons. Some discussion is presented about this subject.