Thermodynamic measurements of Zn and Al freezing temperatures using an InGaAs-based, near-infrared radiation thermometer 3 (NIRT3)

Thermodynamic temperature measurements of Al and Zn points using a near-infrared radiation thermometer 3 (NIRT3) are described. The NIRT3 was constructed for long-term stable operation, low size-of-source and characterized for linearity. The spectral responsivity was measured using tuneable near-infrared lasers and window-less InGaAs diodes. The spectral responsivity of the NIRT3 was scaled using a Au freezing-temperature blackbody and an absolute visible radiation thermometer. We then measured both the Al and Zn freezing temperatures and these measurements are compared against T-T ₉₀ values estimated by the Consultative Committee for Thermometry. (paper)