(Photo)pyroelectric method and device with modulated Peltier element for thermophysical characterization of materials

Abstract
The modulated Peltier element proves to be a stable, reproducible, easy to control and economic source of low frequency heat waves that can be used in (photo)thermal experiments in combination with (or instead of) currently employed optical excitation. When used with pyroelectric sensors, the device has a flat frequency characteristic between 0.03 and 4 Hz, well above 0.027 Hz that corresponds to the thermal time constant of the Peltier element ( s). The signal-to-noise ratio is more than 50 times better than that achieved with a HeNe laser source, especially at very low frequency. Using the new cell we determined the pyroelectric coefficient Cm^-2K^-1 of the PVDF sensor and the thermal diffusivity m²s^-1 of the ceramic plate of the Peltier element.