Influence of Mn Doping on the Crystal Structure, and Optical and Magnetic Properties of <inline-formula> <tex-math notation="TeX">${\rm SrTiO}_{3}$ </tex-math></inline-formula> Compounds

Abstract

This paper presents the influence of Mn doping on the structural characterization, and optical and magnetic properties of ${\rm SrTi}_{1-x}{\rm Mn}_{x}{\rm O}_{3}(x=0.0\hbox{--}0.1)$ materials prepared by a solid-state reaction method. The detailed analyses of X-ray diffraction patterns indicate an incorporation of Mn dopants into Ti sites of the ${\rm SrTiO}_{3}$ host lattice. There is a cubic to tetragonal transformation, which takes place at a threshold concentration $x\approx 0.04$ . The optical absorption spectra show a rapid increase in the absorption coefficient. The bandgap energy $(E_{g})$ related to the direct electron transition decreases with increasing Mn concentration: $E_{g}$ decreases from 3.15 eV for $x=0$ to 1.28 eV for $x=0.10$ . From this point of view, the ${\rm SrTi}_{1-x}{\rm Mn}_{x}{\rm O}_{3}$ materials are considered as promising materials for photocatalytic applications. Interestingly, while the samples with $x=0.0\hbox{--}0.02$ are diamagnetic, the others with $x=0.04\hbox{--}0.10$ exhibit weak ferromagnetism. The ferromagnetic order increases with increasing Mn concentration. Based on the results of structural and optical analyses, the nature of magnetism in the samples is explained thoroughly.