Figure 1

Valence states and defect characterization of Mg + Ta co-doped rutile TiO₂. (a–c) Core level XPS (open circle) and corresponding fitting results (solid lines) of Ti 2p (a), Ta 4 f (b), O 1 s (c) electrons of 5% Mg + Ta co-doped rutile TiO₂. (d) EPR spectrum of 0.5% Mg + Ta co-doped rutile TiO₂ measured at 10 K. Insets in (a) and (c) are enlarged views to clearly show the shoulders in the blue dotted boxes.