A practical extension of the 3ω method to multilayer structures

An improved data reduction method is used to extend the popular 3ω method to general layered geometries. This approach utilizes an unapproximated analytical solution, cast in terms of thermal impedance, to simultaneously measure thermal conductivity, thermal capacity, conductivity anisotropy, and interlayer contact resistance in multilayer planar structures. This method places no restrictions on the number or thickness of individual material layers, and it allows experimental measurements to be taken over a much wider range of frequencies than was previously possible. The search algorithm associated with the model is straightforward, robust, and requires no specialized software to compose. Experimental results are presented for a two-layer borosilicate glass/zeolite structure as well as a Si∕SiO2 structure. In both instances, the algorithm was able to simultaneously extract thermal conductivity and thermal diffusivity values using a single series of 3ω measurements.