“…For all the samples, four Raman bands centered at ∼144, ∼396, ∼518, ∼639 cm −1 , and a weak shoulder at ∼197 cm −1 were observed. It has been reported previously that anatase TiO 2 has six active Raman modes including 3E g modes at ∼145, ∼197, and 638 cm −1 , 2B 1g mode at ∼399 and ∼519 cm −1 , as well as a A 1g at ∼513 cm −1 [8,[40][41][42][43]. On the other hand, rutile phase has 4 Raman active modes at 143, 447, 612, and 826 cm −1 [44] while brookite phase has 3 Raman active modes at 247, 326, and 366 cm −1 [45,46].…”