Structure, optical properties and antimicrobial activities of MgO-Bi_2-xCr_xO₃ nanocomposites prepared via...

MgO-Bi_2-xCr_xO₃ nanocomposites for x = 0 and 0.07 were fabricated using the solvent-deficient route. X-ray diffraction method, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDXA) and UV-Vis spectroscopy were employed to study the properties. The samples were also evaluated for the antibacterial activity. The x = 0 sample showed a dominant monoclinic crystalline structure of [Formula: see text] phase. No peaks attributed to MgO were observed. Cr-doped [Formula: see text] in which Bi was substituted showed that [Formula: see text] phase was also present in the [Formula: see text] composite. The Scherrer formula was employed to determine the crystallite size of the samples. The Cr-doped sample showed a decrease in the crystallite size. The microstructures of the non-doped MgO-Bi₂O₃ and MgO-Bi_1.93Cr_0.07O₃ composites consisted of micrometer sized grains and were uniformly distributed. Direct transition energy gap, [Formula: see text] decreased from 3.14 to 2.77 eV with Cr-doping as determined from UV-Vis spectroscopy. The Cr-doped [Formula: see text] nanocomposites exhibited two energy gaps at 2.36 and 2.76 eV. The antibacterial activity was determined against gram-negative bacteria (Salmonella typhimurium and Pseudomonas aeruginosa) and gram-positive bacteria (Staphylococcus aureus) by disc diffusion method. Cr-doping led to a decrease in inhibitory activity of MgO-Bi_2-xCr_xO₃ nanocomposite against the various types of bacteria.