Study on Charge Transfer Mechanism in Mechanically Milled Co3O4 by UV-Vis Spectral Analysis. (2019) - Raval, P.Y.
Abstract: The consequences of mechanical milling instigated strain and particle size reduction on optical properties of cobalt oxide (Co3 O4 ) have been deliberated by virtue of X-ray powder diffractometry, transmission electron microscopy and UV-Vis spectroscopy at 300 K. Based on this study it is deduced that: (i) the lattice constant and thus X-ray density values are not affected by mechanical milling induced particle size reduction but the strain is generated on 7 hrs. of milling in Co3 O4 spinel composition (ii) the UV-Vis spectra for un-milled and 7 hrs milled samples show two absorption bands corresponding to Co 2+ -O 2- and Co 3+ -O 2- charge transfer mechanisms. The observed redshift in energy band gap is mainly due to the milling induced vacancies but vacancy formation is not identical at the tetrahedral and octahedral environments. The red-shifted electronic band for the milled sample is also due to the highly stressed particles. The mean refractive index, molar electronic polarizability, and optical energy band gap have been determined from X-ray density value.