A Novel Technique for the Determination of Thermal Diffusivities and Conductivities and its Application to Porous PZT Samples

A modification of a technique for the measurement of the thermal diffusivity of thin solid materials is presented. It is based on the measurement of the phase retardation of a thermal wave passing through the test material by means of a PZT pyroelectric detector. It is not necessary to know either the pyroelectric coefficient of the detector or the intensity of the laser beam. The technique was applied to the study of several sets of Ferroperm Pz27 ceramic samples with porosities of 20, 25 and 30%. One sample set was poled and the pores were partially filled with the fluid using during poling. A second set was not poled. Scanning electron micrographs indicated that the 20 and 25% samples had 0-3 connectivity with a small amount of 3-3 connectivity. The connectivity of the 30% porosity sample was almost completely 3-3. The heat capacity of the Pz27 was determined in order that thermal conductivities could be calculated. The poled porous samples had thermal conductivities intermediate between that of a commercial dense Pz27 sample and those of unpoled materials.