Thermal diffusivity measurement of boron nitride by photoacoustic spectroscopy

A photoacoustic spectrometer (PAS) is a very common method to measure non-radiative decay. When modulated electromagnetic light interacts with any solid powder sample, their thermal energy production is due to non-radiative decay. Then acoustic noise is produced due to temperature difference which is formed by the periodic heat transfer from the optical source. In this work, we have fabricated a PA cell and a pre-amplifier circuit and optimized them by parametric studies to get the desired signal. For the optimum signal, the volume of the cell cavity is found to be 5.30 x 10(-6) m(3). We have successfully syn-thesized Boron nitride (BN) by simple hydrothermal method with NH4Cl (Sample I) and without NH4Cl (Sample II). The XRD and FESEM data confirm the crystal phase and morphological structure of the syn-thesized material. The thermal diffusivity of sample I is obtained (7.22-8.31) x 10(-6) m(2)/s. Similarly, for sample II, the thermal diffusivity is found to be (7.38-8.72) x 10(-6) m(2)/s. Copyright (C) 2022 Elsevier Ltd. All rights reserved.