Simultaneous measurement of thermal diffusivity, thermal conductivity and specific heat by impulse-response photopyroelectric spectrometry

Abstract

A novel photothermal technique is developed, which enables the simultaneous measurement of the thermal diffusivity α, thermal conductivity κ, and the specific heat C of a sample. The technique is based on frequency-modulated time-delay photopyroelectric spectrometry (FM-TDPS), which consists of chirped laser excitation of the sample and detection of the thermal impulse response by a thin-film pyroelectric detector. No calibration is required for the measurements; absolute values for α, κ, and C may be obtained without having to employ a reference sample. Results on superconducting YBa2Cu3O7−x are reported for the temperature range 50–300 K; the values obtained compare favorably with reported measurements of α, κ, and C for YBa2Cu3O7−x , which previously required separate experiments for their determination.