Measurement of thermal diffusivity of small, high conductivity samples using a phase sensitive technique

Abstract

We have developed a phase sensitive technique for measuring the thermal diffusivity of thin samples which is particularly useful for high conductivity materials such as diamond. The technique is based on a relationship between the experimentally determined frequency dependent phase shift of a thermal wave, and the geometry and thermal diffusivity of the sample. Our analysis correctly describes the phase shift for both thermally thick and thermally thin samples, which greatly expands the useful frequency range of phase shift measurements. The experimental apparatus consists of common laboratory electronics, is relatively easy to implement, and is useful over a wide range of temperatures. Measurements on glass, copper, and diamond samples at room temperature show that the accuracy and precision of the technique compares favorably with standard methods.