Study of optical and thermal properties of terbium manganate nanoparticles

Abstract

We have studied the optical and thermal properties of terbium manganate (TbMnO3) nanoparticles at room temperature. The sample is successfully synthesized by sol–gel method. An orthorhombic phase of the sample is confirmed from XRD analysis. The Williamson–Hall analysis is done to study the contribution of strain and crystallite size on the peak broadening of the synthesized nanoparticles. Elemental analysis of the sample is evaluated from the EDX profile. TbMnO3 nanoparticles exhibit strong absorption in the UV region. The optical band gap is calculated using the Tauc method from UV–Vis absorption spectroscopic analysis. Urbach energy is found to be 0.28 eV for the existence of band distortion and defects in the material. Thermal behaviour of these nanoparticles is determined by non-isothermal thermogravimetric analysis at inert atmosphere. The effect of different heating rates (10, 12, 15 and 20 K/min) on thermal properties of the sample is also investigated. The kinetic parameters are evaluated using different model-free methods in the analysis of solid-state kinetics for thermal behaviour of TbMnO3 nanoparticles. The Coats–Redfern method is used here to determine the apparent reaction order which is found to be ~ 2.