File:Bati03.png

English: In this report, barium titanate (BaTiO3) nanoparticles were synthesized at 200°C by sol-gel hydrothermal process and annealed at five different temperatures from 100-500°C. The sample synthesized at 200°C exhibited distorted cubic structure with a mishmash of tetragonal and orthorhombic phase which was analyzed from XRD studies. To further empathize its characteristic features, the samples were annealed for various temperatures. The grain size and lattice parameters of the annealed samples were calculated from the XRD spectrum. When the annealing temperature increases a non-uniformity in the grain size and lattice parameters was observed in the BaTiO3 nanoparticles. XRD also reveals that there was phase transition from distorted cubic to tetragonal phase and this phase was stable for all the annealed samples. The morphology of annealed barium titanate nanoparticles was analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) which specifies the presence of spheres and rods. Optical studies were carried out by UV-Vis, Photoluminescence and Raman Spectroscopy. The change in non-linear optical (NLO) activity of BaTiO3 nanoparticles were studied using second harmonic generation (SHG). Samples that possess phase distortion produced SHG as it lacks center of symmetry. Remarkably, the annealing process created an effective atmosphere for the formation of single crystalline tetragonal phase within 300-500°C, which is normally possible only above 800°C.

MAYANDI, JEYANTHINATH and Mahalakshmi, Selvaraj and Venkatesan, Ragavendran and Asokan, Vijay Shankar and Alam, Mohammed Mujahid and Pearce, Joshua M. and Venkatachalapathy, Vishnukanthan, Effect of Annealing on the Structural, Optical Properties of Barium Titanate Nanoparticles and its Impact on Second Harmonic Generation. Available at SSRN: https://ssrn.com/abstract=4496400 or http://dx.doi.org/10.2139/ssrn.4496400