Photoacoustic investigation of phase transitions in solids

The use of the photoacoustic effect in the investigation of first- and second-order phase transitions has been examined. Changes in the amplitude of the photoacoustic signal across the phase transition are compared with changes in thermal properties such as specific heat and thermal diffusivity. The systems studied include NaNO2, TlNO3, CsNO3, NH4NO3, BaTiO3, CoO, Cu2HgI4, VO2 and V3O5. The current photoacoustic studies are discussed in the light of the theoretical models available.