Structure, optical properties and antimicrobial activities of MgO–Bi2−xCrxO3 nanocomposites prepared via solvent-deficient method
Annas Al-Sharabi, Kholod S. S. Sada’a, Ahmed AL-Osta, R. Abd‐Shukor
Abstract
Abstract MgO–Bi 2− x Cr x O 3 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 $$\alpha\text{-}{\text{Bi}}_{2}{\text{O}}_{3}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>α</mml:mi> <mml:msub> <mml:mtext>-Bi</mml:mtext> <mml:mn>2</mml:mn> </mml:msub> <mml:msub> <mml:mtext>O</mml:mtext> <mml:mn>3</mml:mn> </mml:msub> </mml:mrow> </mml:math> phase. No peaks attributed to MgO were observed. Cr-doped $$\text{MgO}{-}{\text{Bi}}_{2}{\text{O}}_{3}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mtext>MgO</mml:mtext> <mml:mo>-</mml:mo> <mml:msub> <mml:mtext>Bi</mml:mtext> <mml:mn>2</mml:mn> </mml:msub> <mml:msub> <mml:mtext>O</mml:mtext> <mml:mn>3</mml:mn> </mml:msub> </mml:mrow> </mml:math> in which Bi was substituted showed that $${\text{the tetragonal BiCrO}}_{3}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mrow> <mml:mtext>the tetragonal BiCrO</mml:mtext> </mml:mrow> <mml:mn>3</mml:mn> </mml:msub> </mml:math> phase was also present in the $$\text{MgO}{-}{\text{Bi}}_{2}{\text{O}}_{3}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mtext>MgO</mml:mtext> <mml:mo>-</mml:mo> <mml:msub> <mml:mtext>Bi</mml:mtext> <mml:mn>2</mml:mn> </mml:msub> <mml:msub> <mml:mtext>O</mml:mtext> <mml:mn>3</mml:mn> </mml:msub> </mml:mrow> </mml:math> 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–Bi 2 O 3 and MgO–Bi 1.93 Cr 0.07 O 3 composites consisted of micrometer sized grains and were uniformly distributed. Direct transition energy gap, $${E}_{\text{g}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>E</mml:mi> <mml:mtext>g</mml:mtext> </mml:msub> </mml:math> decreased from 3.14 to 2.77 eV with Cr-doping as determined from UV–Vis spectroscopy. The Cr-doped $$\text{MgO}{-}{\text{Bi}}_{2}{\text{O}}_{3}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mtext>MgO</mml:mtext> <mml:mo>-</mml:mo> <mml:msub> <mml:mtext>Bi</mml:mtext> <mml:mn>2</mml:mn> </mml:msub> <mml:msub> <mml:mtext>O</mml:mtext> <mml:mn>3</mml:mn> </mml:msub> </mml:mrow> </mml:math> 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− x Cr x O 3 nanocomposite against the various types of bacteria.