INVERSE PHOTOPYROELECTRIC DETECTION OF PHASE-TRANSITIONS

The inverse photopyroelectric (IPPE) configuration was used in order to detect ther antiferromagnetic-paramagnetic phase transition in Cr2O3. It was demonstrated both theoretically and experimentally that the IPPE scheme is able to detect phase transitions in the case when the pyroelectric sensor is thermally thin and optically opaque. The main advantage of this configuration, compared with the standard one, is the elimination of all the possible detection problems connected with the optical properties of the sample (transparency, thermal reflectance, etc.). For a thermally thin sample the amplitude of the IPPE signal depends only on the specimen specific heat, allowing its direct calculation. A similar direct calculation of the sample effusivity is possible sometimes in the thermally-thick limit.