• Journal of Sensor Science and Technology
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• v.17 no.3
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• pp.188-194
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• 2008

For the accurate calibrations of thermometers at low temperatures, triple points of oxygen and argon have been realized using sealed-type triple point cells. The triple points were realized with both adiabatic and continuous heating methods. The resistance of three capsule-type standard platinum resistance thermometers were measured at the triple points of oxygen, argon, mercury and water for the calibrations of these thermometers in the range from $-220^{\circ}C$ to $0.01^{\circ}C$. The extended uncertainty, with the coverage factor of 2, of the calibration in this range is smaller than 1 mK.