Automated apparatus for the determination of the specific heat and the thermal diffusivity of nonconducting solids using ac techniques

Abstract

A fully automated experimental setup is described that allows the determination of the heat capacity and thermal diffusivity on the same piece of a nonconducting thin solid sample. Both properties are measured using ac techniques. Measurements have been made on microscope glass cover slides for temperatures between 25 and 300 K. The values obtained for the specific heat are within 5% of those reported in the literature and the values of the thermal diffusivity are within 10% of reported values.

An Analysis for Measurement of Thermal Diffusivity Components of Anisotropic Platelike Samples by AC Calorimetric Method

“…where a sl is the constant slope of the phase vs the square root of the frequency. The result of a sl for isotropic material (κ = 1) in this study is consistent with √ π 3 derived by Yang et al 9) Equation (18) indicates that the anisotropic effect results of thermal diffusivity components, κ = π d 2 /D x a 2 sl . This step then leads to the cross-plane thermal diffusivity, D y = π d 2 /a 2 sl .…”

“…Regarding the measurement of D y , Yang et al 9) and Kato et al 10) have proposed ac calorimetric methods for measuring the cross-plane thermal diffusivity. In a 1D model by Yang et al, 9) the thermal diffusivity perpendicular to the sample surface is determined from the constant slope of the phase vs the square root of the frequency in the high-frequency region. The present study has noted that the ac light heating method is not suitable for determining the D y of semitransparent samples if the thermocouples are placed under the light beam.…”

“…With larger sample thickness, assuming a one-dimensional (1D) temperature distribution becomes invalid. The two-dimensional (2D) effect on the ac temperature must then be included and has been analyzed by Yamane et al, 6) Hatta et al 7) and Takahashi et al 8) The ac calorimetric methods for measuring the cross-plane thermal diffusivity of a film have also been proposed by Yang et al 9) and Kato et al 10) using a one-dimensional model.…”

Heat-capacity study of butane on graphite

“…1 evolved smoothly from the submonolayer triple line, we identify them as corresponding to the continuation of the monolayer melting curve. 23 Similar melting temperature increases near monolayer completion have been observed in other physisorbed systems ͑the noble gases, N 2 , CO, CH 4 , etc.͒. 15 Computer simulations suggest that these increases result from changes in the relative importance of the different vacancy-production processes in the film as a function of increasing coverage.…”

“…Details of the experimental setup, procedures, and of the ac technique have been discussed in some detail elsewhere. 22,23 II. RESULTS…”