Nano-vanadium doping-driven low temperature structural phase transformation in titania

Synthesis, X-ray diffraction (XRD), morphological, and magnetization studies of nano-vanadium doped TiO₂ are reported here. Commercially available anatase nano-TiO₂ and nano-vanadium powders were mixed and heat-treated in air at 600°C. X-ray diffraction revealed a complete anatase to rutile phase transformation at low vanadium content of 5%. Samples annealed under different environments such as Ar and O₂ also exhibited the same trend. Such a phase transformation at relatively low temperature (600°C) has been explained based on enhanced reactivity between vanadium and TiO₂ powders. Scanning electron micrographs elucidated the tunable microstructures from irregular-shaped, in the pristine TiO₂ (x = 0.0), to well-faceted polyhedra V-doped (x = 0.05 to 0.15) samples. Room temperature magnetization results revealed that upto 10% vanadium doping the samples are diamagnetic in nature and exhibit a paramagnetic transition for higher V content which presumably can be attributed to the presence of vanadium pentaoxide observed in the XRD.