A NEW TECHNIQUE TO OBTAIN A FAST THERMOCOUPLE SENSOR FOR THERMAL-DIFFUSIVITY MEASUREMENTS IN AN EXTENDED TEMPERATURE-RANGE

An improved ac method to measure the thermal diffusivity in an extende d temperature range is presented. The basic idea is to solder thermoco uple wires directly on the sample, so that the sample itself acts as a thermocouple junction and the relaxation time for the temperature mea surement becomes negligible. This new technique allows one to measure smaller samples and to increase the frequency of measurement so that t he thermal losses could in principle be completely neglected. Finally, by the particular geometry a concurrent measurement of the electrical resistivity is obtained.