Niobium Doped Ti O, (Nb:Ti02) Effects of Doping Concentration on the Optical Properties of Ti O2

Abstract

The optical band gaps and crystal structure were inve stig ated on niobium doped TiO~ (for atomic niobium concentrations ranging from 0.02 -0.06 at. % in the composite) prepared by high temperature diffusion method. The Nb:Ti02 films displayed an enhanced visible light absorption \\ ith a red shift of I S.l I1Ill of the optical absorption edge from 39~ nrn for pure TiCh film to 4 J 2:2 nrn for 0.04 at % niobium concentration representing a band gap lowering of 0 J S J eV due to the donor -t , pe behavior or niobium. :\s the niobium concentration increased. the enhancement in light absorption at the inve sug ated • onccmration range goes through a maximum at 004 at. ';0 ofNbS- with ill In nnurn band gap of3 !Ji/t'V Despite higher rutilization. at the doping temperature of 850°C used. cr:~t," sizes (39-43 nm ) obtained lrorn :\-ray diffraction spectra depicted a significant increase in surface areas which is anribured t() rciardat ion of anatase - rutile phase transformation caused bv NbTiO? m auix