Materials Science and Engineering B 178 (2013) 400–408 Contents lists available at SciVerse ScienceDirect Materials Science and Engineering B j o ur nal homep age: www.elsevier.com/locate/mseb Photoluminescence and thermoluminescence studies of Tb 3+ doped ZnO nanorods Partha P. Pal ∗ , Jairam Manam Department of Applied Physics, Indian School of Mines, Dhanbad 826004, India a r t i c l e i n f o Article history: Received 23 July 2012 Received in revised form 22 November 2012 Accepted 6 January 2013 Available online 19 January 2013 Keywords: Photoluminescence Thermoluminescence Zinc oxide Rare-earth Nanorods Nanoflakes a b s t r a c t Here in, the synthesis of the terbium doped zinc oxide (ZnO:Tb 3+ ) nanorods via room temperature chemi- cal 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 crys- talline 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 diam- eter 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 spec- tra of the Tb 3+ -doped sample exhibited bright bluish green and green emissions at 490 nm ( 5 D 4 → 7 F 6 ) and 544 nm ( 5 D 4 → 7 F 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 pro- cess from ZnO host to Tb 3+ is observed in PL emission and excitation spectra of Tb 3+ -doped ZnO ions. The doped sample exhibits a strong TL glow peak at 255 ◦ C compared to the prominent glow peak at 190 ◦ 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 ◦ C for the Tb 3+ doped sample has an activation energy 0.98 eV and frequency factor 2.77 × 10 8 s -1 . © 2013 Elsevier B.V. All rights reserved. 1. Introduction In the present decade, man has become successful to exploit the luminescence properties of phosphor materials to a great extent. The photoluminescence and thermoluminescence phenomena from the materials were thoroughly investigated and applied in different fields to the mankind. The research is still going on for the search of better luminescent materials. For the past few years, zinc oxide (ZnO), one of the II–VI semiconductors, has become one of the most promising luminescent materials for the much needed optoelectronic devices operating in the blue and UV region and the transparent conducting and piezoelectric materials for fabricating solar cells, electrodes, and sensors [1]. Owing to a direct wide band gap (3.37 eV), large exciton binding energy (60 meV), and superior conducting properties based on oxygen vacancies, this material is effectively used for various applications such as vacuum fluorescent display (VFD), field emission display (FED) and electroluminescent ∗ Corresponding author. Tel.: +91 326 2235439; fax: +91 326 2296563. E-mail addresses: phys.ppal@gmail.com, parthapratimpal05@gmail.com (P.P. Pal). display (ELD) [2–6]. Due to its wide band gap, ZnO is regarded as an important candidate for the application in laser diodes and UV light emitting diodes [5,6]. Apart from the wide band gap, the large exciton binding energy (60 meV) at room temperature and an excellent thermal and chemical stability made it an attractive phosphor for the low voltage emissive displays [7]. In order to design the electrical, optical and magnetic properties of ZnO for the practical applications, the control of shape and crystal structure are very important, and the synthesis of novel nanostructures is highly desired. For example, the preparation of various nanostruc- tures, including nanorods, nanowires, nanotubes, nanobelts, and nanobranches, has been widely investigated. However, it has been realized that tuning the band gap only by changing the morphology or size of nanocrystal is not well suited for some applications such as fluorescent imaging and nanoelectronics. It is well-known that the addition of rare earth impurities into a wide-band gap semiconductor can often induce dramatic changes in the optical, electrical, and magnetic properties. Therefore vari- ous rare earth doped nanocrystals exhibit specific properties and ZnO is regarded as an excellent host material for the doping of the rare earth and transition metal ions. The optical proper- ties of ZnO are immensely modified if it is being doped with 0921-5107/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.mseb.2013.01.006