Photoluminescence and thermoluminescence studies of Tb 3+ doped ZnO nanorods

Here in, the synthesis of the terbium doped zinc oxide (ZnO:Tb3+) nanorods via room temperature chemical co-precipitation was explored and their structural, photoluminescence (PL) and thermoluminescence (TL) studies were investigated in detail. The present samples were found to have pure hexagonal wurtzite crystal structure. The as obtained samples were broadly composed of nanoflakes while the highly crystalline nanorods have been formed due to low temperature annealing of the as synthesized samples. The diameters of the nanoflakes are found to be in the range 50-60 nm whereas the nanorods have diameter 60-90 nm and length 700-900 nm. FTIR study shows Zn-O stretching band at 475 cm(-1) showing improved crystal quality with annealing. The bands at 1545 and 1431 cm(-1) are attributed to asymmetric and symmetric C=O stretching vibration modes. The diffuse reflectance spectra show band edge emission near 390 nm and a blue shift of the absorption edge with higher concentration of Tb doping. The PL spectra of the Tb3+-doped sample exhibited bright bluish green and green emissions at 490 nm (D-5(4) -> F-7(6)) and 544 nm (D-5(4) -> F-7(5)) respectively which is much more intense then the blue (450 nm), bluish green (472 nm) and broad green emission (532 nm) for the undoped sample. An efficient energy transfer process from ZnO host to Tb3+ is observed in PL emission and excitation spectra of Tb3+-doped ZnO ions. The doped sample exhibits a strong TL glow peak at 255 degrees C compared to the prominent glow peak at 190 degrees C for the undoped sample. The higher temperature peaks are found to obey first order kinetics whereas the lower temperature peaks obey 2nd order kinetics. The glow peak at 255(degrees)C for the Tb3+ doped sample has an activation energy 0.98 eV and frequency factor 2.77 x 10(8) s(-1). (C) 2013 Elsevier B.V. All rights reserved.