Pressure coefficient of thermoelectric power of platinum/platinum−10% rhodium and Chromel/Alumel thermocouples

Abstract

A differential measurement between two thermocouples of the same type, one under hydrostatic pressure and the other at zero pressure, was undertaken at temperatures up to 950 °C and pressures to 2 kbar, for platinum/platinum−10% rhodium (P/P10R) and Chromel/Alumel (C/A) couples, using an externally heated pressure cell. The correction term for P/P10R rises monotonically and levels off to a value of −0.44±0.02 °C/kbar at 800 °C. The correction term for C/A is in the opposite sense: it remains less than 0.1°C/kbar up to 450 °C where it begins to rise, eventually reaching 0.42±0.02 °C/kbar at 950 °C.