The 3 omega technique for measuring dynamic specific heat and thermal conductivity of a liquid or solid

We show how to measure dynamic specific heat and thermal conductivity of a solid or liquid sample using the 3 omega technique, which is an ac-modulation method where we use a heater simultaneously as the sensor. By varying the width of the heater relative to the thermal decay length, one can choose the proper regime to measure thermal conductivity or specific heat. The technique is applied to window glass and the results confirm the validity of the method. Experimental results for potassium dihydrogen phosphate crystal demonstrate the first-order transition at the Curie point, and the dynamic specific heat of supercooled liquid potassium-calcium nitrate is shown. (C) 1996 American Institute of Physics.