Morphological and Optical changes with dopant concentration of Bi₂O₃ in Al₂Bi₂O_6-δ nano-particulates

Abstract

In present scenario, technologies based on nanomaterials applications are taken at the top priorties because of their advanced properties. The materials have colourful size-dependent properties at nanoscale because of its significant ratio of surface area to volume. In this study, different compositions of alumina nanocrystalline materials incorporated with Bi2O3 (5%,10%,20%) were prepared by using micro wave treated (at 100°C for 15 minutes) chemical route techniques at calcination temperature of 600°C for a duration of 2 hours resulted in uniform sized nano-particulates were obtained. The ultrafine powder samples were analyzed by using techniques including UV-Vis- NIR spectrum, XRD, HRTEM, FTIR & FESEM etc. The XRD data reveals that the crystallite size of the nano crystals increased from 28.9nm (Pure alumina), 30.1nm (5% Bi2O3doped), 36.8nm (10% Bi2O3doped), 41.21 nm (20% Bi2O3doped) respectively and indicates increasing trend with dopant concentration for fixed calcination temperature of 600°C for a duration of 2 hours. The IR spectrum were deployed to examine the functional group existing in samples and concluded that corresponding IR alps were found at different wave numbers for each dopant concentration, with multiple alps/peaks attributed at 3300cm−1and at 1600cm−1were due to-OH group’s vibration mode and water content in the surroundings respectively. The alp at 1300 cm−1 was related to the adsorption of NO2 and CO2 in the surroundings and nitrate salt used for preparing the samples, while other alps at 582 cm−1 (O-Al-O) and 512 cm− 1(O-Bi-O) were related to various metal oxide vibrations. In UV-VIS spectroscopy, the tauc plot revealed that the energy band gap was 1.67 eV, 1.85eV, 2.72eV and 2.89 eV respectively. The microscopy through field emission of scanning of electron (FESEM) image displayed truncated spherical particles that were agglomerated in nature. The HRTEM findings are consistent with the results obtained from XRD data and FESEM.