THERMAL-CONDUCTIVITY MEASUREMENTS OF INSULATING SINGLE-CRYSTALS

We have utilized a new technique, called the 3omega method, to measure the thermal conductivity of insulating solids, triglycine sulfate (TGS) and sodium chloride (NaCl). The method uses, as a heater and sensor simultaneously, a long and thin metallic wire directly evaporated onto the surface of a sample. An ac electric current at angular frequency omega is applied to the wire to generate heat. The thermal response of the sample is then picked up as a voltage at 3omega across the heater. The voltage is inversely proportional to the thermal conductivity of the sample. The temperature dependences of the thermal conductivities of TGS and NaCl are discussed in terms of the kinetic theory of heat transport.X115sci