Temperature Coefficients of Resistivity of Rh-Fe Thin Films for Cryogenic Thermometer Use

Abstract

The resistivity and its temperature coefficients were measured on Rh-Fe thin films between 4.2 K and room temperature to estimate their thermometric sensitivity. The films were sputter deposited on sapphire substrates from a Rh-Fe(0.5 atm%) target. The temperature coefficients are close to those of high-purity, well-annealed Rh-Fe(0.5 atm%) wires although the resistivity is higher than that of the wires. Rh-Fe thin film resistors have a high potential for cryogenic thermometers because dilute iron in the films is as effective as that in bulk wires to enhance the temperature coefficients.

Tests of the Stability of Chinese RhFe Resistance Thermometers at Low Temperatures

“…RIRTs were developed by R. Rusby at National Physical Laboratory and produced by H. Tinsley and Co Ltd in the early 1970s [2,3]. Later, they were produced by other companies and institutes [4][5][6], but despite this the availability of the thermometers decreased and a new source of supply was needed. Several years ago, the Technical Institute of Physics and Chemistry (TIPC), Chinese Academy of Sciences, developed its own technology for making wire of Rh-0.5 at% Fe alloy which was used in the production of new thermometers [7,8].…”