Simultaneous measurement of thethermal diffusivity and specific heat near phase transitions

Abstract

A technique for measuring the absolute thermal diffusivity along with the relative specific heat is introduced which is readily adaptable to a wide variety of applications. The thermal diffusivity and specific heat of CoO, near the antiferromagnetic transition; of SrTiO 3, near the structural phase transition; of Cr, near the first-order SDW-paramagnetic transition; and of EuO, near the ferromagnetic Curie point were measured. Except for SrTiO 3, the thermal diffusivities are found to mirror the specific heats, with no evidence for anomalies in the thermal conductivities, contrary to some earlier reports. A step increase in the thermal conductivity is observed on passing through the structural transition of SrTiO 3 from below which is of the same relative size as the step decrease of specific heat at T c .