MgTiO3 (MTO) thin films were prepared by the
polymeric
precursor method with posterior spin-coating deposition. The films
were deposited on Pt(111)/Ti/SiO2/Si(100) substrates and
heat treated at 350 °C for 2 h and then heat treated at 400,
450, 500, 550, 600, 650 and 700 °C for 2 h. The degree of structural
order–disorder, optical properties, and morphology of the MTO
thin films were investigated by X-ray diffraction (XRD), micro-Raman
spectroscopy (MR), ultraviolet–visible (UV–vis) absorption
spectroscopy, photoluminescence (PL) measurements, and field-emission
gun scanning electron microscopy (FEG-SEM) to investigate the morphology.
XRD revealed that an increase in the annealing temperature resulted
in a structural organization of MTO thin films. First-principles quantum
mechanical calculations based on density functional theory (B3LYP
level) were employed to study the electronic structure of ordered
and disordered asymmetric models. The electronic properties were analyzed,
and the relevance of the present theoretical and experimental results
was discussed in the light of PL behavior. The presence of localized
electronic levels and a charge gradient in the band gap due to a break
in the symmetry are responsible for the PL in disordered MTO lattice.