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TitleUncertainties in the SPRT subranges of ITS-90: Topics for further research
Publication TypeJournal Article
Year of Publication2010
AuthorsWhite, D.R., Ballico M., Del Campo D., Duris S., Filipe E., Ivanova A., A. Dogan Kartal, Mendez-Lango E., Meyer C., Pavese F., Peruzzi A., Renaot E., Rudtsch S., Wang T., and Yamazawa K.
JournalInternational Journal of Thermophysics
Pagination1749 - 1761
Date Published2010
ISSN0195928X (ISSN)
KeywordsFixed points, Freezing point, high temperature, Impurities, Impurities in, Isotopic effects, Liquidus, Low temperatures, Nonuniqueness, Oxidation, Partial pressure of oxygen, Paucity of data, Platinum, Platinum resistance thermometry, Sources of uncertainty, Standard platinum resistance thermometer, Thermal environment, Thermometers, Triple points, uncertainty, Vacancy effects
AbstractThe CCT has completed the guide summarizing the uncertainties in the realization of the SPRT subranges of ITS-90 between the triple point of neon (24.5561 K) and the freezing point of silver (961.78 °C). This article identifies aspects of standard platinum resistance thermometry where either data or models are lacking and further research is required. In the calibration of SPRTs, the two main concerns are the need for data on liquidus slopes for the different impurities in the fixed points and improved understanding of the impact of the thermal environment of the fixed point on the realized temperature. In the use of SPRTs, the two largest sources of uncertainty are Types 1 and 3 non-uniqueness and oxidation. The causes of Type 3 non-uniqueness are not yet understood, especially at low temperatures, and there is a paucity of data for the high-temperature subranges. In respect of oxidation, there is a need for validation of the models developed in the 1980s, especially in light of the reduced partial pressure of oxygen used in modern SPRTs. A range of other effects including vacancy effects in SPRTs, isotopic effects in fixed points, and improved statistical methods are discussed. © Springer Science+Business Media, LLC 2010.

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