Spatially resolved heat conduction in polar perhydrotriphenylene inclusioncompounds studied by means of thermal waves

Scanning pyroelectric microscopy was applied to study the local thermal dif fusivity in polar perhydrotriphenylene (PHTP) inclusion compounds. A therma l wave technique with special heat flow and pyroelectric detection principl es was used to measure the longitudinal (K-parallel to) and transversal (K- perpendicular to) thermal diffusivity of needle shaped crystals. As expecte d, we have found a higher thermal conductivity along the channel direction: K-parallel to> K-perpendicular to. K-parallel to also showed a variation a long the needle axis, the K-parallel to values near the capping faces being higher than in the center region. Based on these observations we suggest a relation between the longitudinal thermal conductivity and the local densi ty of orientational defects of the dipolar guest molecules which reaches a maximum in the area around the seed. These findings are in agreement with p revious pyroelectric studies, revealing a macrodomain structure and a spati ally dependent pyroelectric activity for two different PHTP inclusion compo unds. (C) 2000 American Institute of Physics. [S0021-8979(00)05416-5].