Abstract
In this study, Ti
0.95
Mn
0.05
O
2−δ
nanostructured thin films were fabricated by pulsed laser deposition technique followed by rapid thermal annealing (RTA) in pure O
2
and N
2
atmospheres. The RTA process induced a substantial change in the surfaces morphology and local atomic structure around Ti
4+
cation that have been studied by means of atomic force microscopy, Raman scattering and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. Raman spectra of the films were resembled to that of TiO
2
rutile phase, and the change in the width of E
g
(434 cm
−1
) Raman active modes has been attributed to oxygen non-stoichiometry. NEXAFS spectra were carried out in synchrotron facility at Ti/Mn
L
3,2
edges and O-
K
edge. The ligand-field splitting, estimated from the energy difference between t
2g
and e
g
features in O K-edge spectra were ~ 2.81 eV for pristine and annealed film, which is a characteristic of the TiO
2
rutile structure, and the asymmetry of t
2g
and e
g
bands at the O-
K
edge has been ascribed to oxygen vacancy (Vo
2+
). The annealing of film in O
2
gas optimized the surface structure and healed the Vo
2+
bridging, while the RTA in N
2
gas introduced Vo and reduced the valence state of Ti
4+
(TiO
2
) into Ti
3+
(Ti
2
O
3
) that have been probed by comparing the NEXAFS spectra of N
2
annealed film with the reference spectra of Ti
2
O
3
. Experimental and atomic multiplet calculations revealed that the Mn ions exist in 2+ valence state.