Photopyroelectric (PPE) determination of thermal diffusivity of Bi2Te2.85Se0.15 sintered thermoelectric semiconductors

Abstract

Thermal diffusivity of the sintered semiconductors was measured by the photopyroelectric (PPE) method. The measurement based on the phase-modulation frequency characteristics was shown to give superior results, eliminating errors expected in the conventional signal amplitude-distance characteristics measurements. Thermal diffusivities of the melt-grown and hot-pressed samples were found to be αmelt(c⊥) = 0.014 cm2/s, αmelt(c//) = 0.011 cm2/s, αhot(c⊥) = 0.012 cm2/s, and αhot(c//) = 0.008 cm2/s, depending on the relation between the c-axis direction of grain and thermal flow direction. The thermal diffusivity of the hot-pressed samples shows a strong dependence on the hot-press pressure through the orientation factor.