Hydrostatic Pressure Effects in Carbon and Germanium Thermometers
The electrical resistance of materials is a function of temperature, pressure, strain, and magnetic fields, as well as other possible variables, This study is concerned with the effect of pressure change, at various temperatures, of two commonly used thermometers in the absence of other extraneous effects. Herr et al.  have reported the pressure dependency of carbon resistors at liquid hydrogen temperature, while Miller et al.  have reported the value at room temperature. Van Itterbeek et al.  have reported the pressure sensitivity to germanium at liquid nitrogen temperature. Van Itterbeek was concerned with exploring the physics of electron mobility through the range where the electrical conduction changes from the intrinsic to the extrinsic mode. The work reported here is concerned with the application of low-temperature thermometers in a varying pressure environment. A 1000-Ω, 1/4-W carbon composition Ohmite resistor and a Honeywell Series III germanium resistance thermometer were pressurized with gaseous helium up to 1000 psig (7.0 × 106N/m2 at the local barometric pressure), The temperature was held constant to better than ±0.01°K near 295°, 76°, 20°, and 4°K. The change in resistance with pressure was observed and the hydrostatic pressure coefficient determined.
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- 1.A. C. Herr, H. G. Terbeek, and M. W. Tieferman, in: Temperature, Its Measurement and Control in Science and Industry, Part 2, Vol. 3, C. M. Herzfield, ed., Reinhold, New York (1962) p. 355.Google Scholar