Temperature dependence of resistance in Black's equation and in calibration for SWEAT and NIST structures: the parameter T/sub EO/

The equation for resistance R(T) at temperature T can be expressed in the form R(T)=(dR/dT).(T-T/sub EO/. When dR/dT is constant over the range of your experiment, T/sub EO/ is then a constant, the temperature at which R(T) extrapolates to zero. If we wish to express the corresponding relationship with /spl beta/(T/sub r/), the temperature coefficient of resistivity (TCR) at temperature T/sub r/, /spl beta/(T/sub r/) is defined in the form /spl beta/(T/sub r/)=(dR/dT/sub r/).(1/R(T/sub r/))=1/(T/sub r/-T/sub EO/). For both these equations it is desirable to use the Kelvin scale for T, especially when activation energy terms occur in the test under consideration. Our experimental measurements of temperature calibration have yielded T/sub EO/ values less than 40 degrees Kelvin, and with sufficient accuracy such that materials properties can be usefully determined provided that the test temperature is not too high. When /spl beta/(T/sub r/) is specified by an independent source, it is necessary that T/sub r/ be included in both theoretical and experimental cases.