Microstructural, optical, and morphological investigations of SnO2 nanomaterials grown by microwave assisted sol gel method

Abstract

Tin Oxide (SnO2) nanomaterials were grown using the microwave-assisted sol–gel method at different concentrations of tin precursor (namely 0.05, 0.1, 0.2, and 0.3 M). Stannous chloride is used as a Sn precursor. Liquid ammonia was used to maintain the pH in the range of 12–13. Synthesis was carried out in an aqueous medium using a Teflon container in a microwave oven for 1 hour. Precipitate was annealed in ambient air for 600oC. Structural, optical, and morphological investigations were done. XRD reveals the growth of the tetragonal phase of SnO2. The prominent presence of (110), (101), and (211) reflections was noticed at 26.6, 33.7, and 52 two-theta values. Tin oxide is transparent in the visible region of the electromagnetic spectrum. However, several attempts have been made to decrease the visible blindness of tin oxide. The band gap is a property of nanomaterials that can tailor their application in the optoelectronic field. Band gap and crystallite size show a prominent relationship in the nano-domain. Strain was not considered while calculating crystallite size using the Scherrer formula. In this investigation, we have measured the crystallite size and other structural features such as strain, stress, deformation energy, dislocation de\ sity, etc using the W-H plot method. All modified models of the W-H method have been utilized for this measurement. A comparative and comprehensive study of structural features was carried out using the Scherrer method, the Williamson–Hall method, and all its modified models. The crystallite size measured by the Scherrer method and various models of the W-H method shows a peak at 0.2 M concentration. Crystallite size plots of various modified W-H methods show similar trends, followed by the Scherrer plot. Strain calculated by Brag’s theory as well as all modified W-H depicts similar behaviour upon changing the concentration. Globular agglomerated morphology was revealed by scanning electron microscopy (SEM). The presence of tin (Sn) and oxygen (O) was confirmed by energy dispersive x-ray spectroscopy. The band gap was obtained using the Tauc theory, which portrays variation in the range of 3.4 to 3.6 eV.