Effect of specimen thickness on the thermal diffusivity of (Sr, K)Zr4(PO4)6 ceramic via a laser-flash technique

Abstract

It has recently been found that the thermal diffusivity of materials determined by means of a pulse method is strongly dependent on the specimen size, due to factors such as a strongly negative temperature-dependent diffusivity and the non-linearity of the detector response, etc. In polycrystalline (Sr, K)Zr4(PO4)6(SrKZP) ceramic, which has a low and weak temperature-dependent thermal conductivity, it has been found the thermal diffusivity increases with increasing specimen thickness and decreases with increasing specimen temperature rise, ΔT. In the limiting of ΔT→0, the SrKZP ceramic shows a thickness-dependent thermal diffusivity. The limiting diffusivity of the ceramic for different thicknesses can be corrected to a value of 7.84 × 10−3cm2s−1 by taking the radial heat conduction effect into account. A reliable measurement of the thermal diffusivity of the SrKZP ceramic can be obtained by using a specimen with thickness not exceeding ∼1 mm and keeping the specimen temperature rise to less than ∼3 °C.