Determination of Freezing Point of Silver usinga Detector Based PhotoelectricLinear Pyrometer

International Journal of Applied Physics

© 2019 by SSRG - IJAP Journal

Volume 6 Issue 2

Year of Publication : 2019

Authors : Arti Rani , Y.P. Singh

10.14445/23500301/IJAP-V6I2P108

How to Cite?

Arti Rani , Y.P. Singh, "Determination of Freezing Point of Silver usinga Detector Based PhotoelectricLinear Pyrometer," SSRG International Journal of Applied Physics, vol. 6,  no. 2, pp. 48-54, 2019. Crossref, https://doi.org/10.14445/23500301/IJAP-V6I2P108

Abstract:

The freezing point of silver (1234.93K) is defined as the junction temperature in the current international temperature scale, ITS-90 to measure it using a contact method by a high temperature platinum resistance thermometer (HTPRT) in the fixed-point cell and using a non-contact method by a radiation pyrometer with a fixed-pointcavity to ascertain the linearity, uniformity and continuity of the scale above 1234 K. In the present work, the temperature of freezing silver was determined using a recently procured and calibrated spectral photoelectric linear pyrometer, LP4. The pyrometer has the traceable calibration from PTB Institute Germany and used as a transfer standard in the measurement process. A silver metal-in-graphite blackbody cavity containing a known quantity of pure silver with a cavity aperture of 10mmwas used in the measurement. The melting and freezing plateaus during phase transitions of silver metal were measured and are shown. The freezing temperature of silver was determined to be 1234.86 K(±0.367 K at k=2),differing by 0.07 K lower than the assigned value in the International Temperature Scale of 1990 (ITS-90) respectively. The fixed point of Ag would serve a unique standard of temperature for calibration of variable sources of transfer standards like tungsten strip filament lamps and spectral and optical pyrometers in the range from 1000 K to 2500 K.

Keywords:

Fixed point, photoelectric pyrometer, blackbody cavity, ITS-90, uncertainty.

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