The study of thermophysical properties is of great importance in several scientific fields. Among them, the heat capacity, for example, is related to the microscopic structure of condensed matter and plays an important role in monitoring the changes in the energy content of a system. Calorimetric techniques are thus of fundamental importance for characterizing physical systems, particularly in the vicinity of phase transitions where energy fluctuations can play an important role. In this work, the ability of the Photopyroelctric calorimetry to study the versus temperature behaviour of the specific heat and of the other thermal parameters in the vicinity of phase transitions is outlined. The working principle, the theoretical basis, the experimental configurations, and the advantages of this technique, with respect to the more conventional ones, have been described and discussed in detail. The integrations in the calorimetric setup giving the possibility to perform, simultaneously with the calorimetric studies, complementary kind of characterizations of optical, structural, and electrical properties are also described. A review of the results obtained with this technique, in all its possible configurations, for the high temperature resolution studies of the thermal parameters over several kinds of phase transitions occurring in different systems is presented and discussed.

The critical behavior of the specific heat, thermal conductivity, and thermal diffusivity at the smectic-A–nematic phase transition of aligned octylcyanobiphenyl (8CB) has been studied with the photopyroelectric technique. Though the values of the thermal transport parameters are substantially different for homeotropic and planar alignment, it has been shown that the thermal diffusivity critical behavior is characterized by the same critical exponent in the two cases. This result suggests that the mode couplings that govern the critical dynamics associated with the thermal parameters are isotropic. The thermal conductivity remains substantially flat, with only a minor increase close to the transition temperature. © 1996 The American Physical Society.

In this paper, an overview of the recent applications of pulsed infrared thermography is presented. Pulsed infrared thermography, which provides stratigraphic information by analyzing the heat diffusion process within the sample after a thermal perturbation, is applied to the investigation of different kinds of cultural heritage artefacts. In particular, it is used to analyze repairs, decorative elements, and casting faults on bronzes, to detect texts hidden or damaged in ancient books/documents, and to characterize paint decorations. Moreover, the integration of pulsed infrared thermography and three-dimensional shape recording methods is proposed in order to provide a three-dimensional representation of the thermographic results. Finally, it is shown how the obtained thermographic results may be crucial from the historical and artistic points of view for understanding the modus operandi of a specific artist and/or of a workshop and for reconstructing the manufacturing process of the analyzed artefacts.

Thermal conductivity, diffusivity, and specific-heat studies were carried out simultaneously over the smectic-A–nematic transition in alkylcyanobiphenyl liquid crystals with different nematic ranges. The critical exponents of all the thermal parameters have been calculated and discussed in terms of the dynamic scaling law of the asymmetric planar magnet model, which applies to three-dimensional XY-like transitions.

We report on the simultaneous “absolute” measurements of the thermal diffusivity and of the thermal effusivity in solid and liquid samples by using only the phase of the so called self-normalized Photopyroelectric signal, performing no other normalization/calibration procedure than that carried out during the actual measurements. Measurements, performed as a function of temperature, are characterized by a temperature resolution adequate to study phase transitions. The obtained results are in excellent agreement with those obtained in the previous studies.