Thermo and photoluminescence properties of Eu 3+ activated hexagonal, monoclinic and cubic gadolinium oxide nanorods N. Dhananjaya a,b , H. Nagabhushana c,n , B.M. Nagabhushana d , B. Rudraswamy a , C. Shivakumara e , K.P. Ramesh f , R.P.S. Chakradhar g,n,1 a Department of Physics, J.B.Campus, Bangalore University, Bangalore 560 056, India b Department of Physics, B.M.S. Institute of Technology, Bangalore 560 064, India c Department of PG studies & Research in Physics, University Science College, Tumkur University, Tumkur 572 103, India d Department of Chemistry, M.S. Ramaiah Institute of Technology, Bangalore 560 054, India e Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012, India f Department of Physics, Indian Institute of Science, Bangalore 560012, India g Glass Technology Lab, Central Glass and Ceramic Research Institute (CSIR), Kolkata 700031, India article info Available online 14 October 2010 Keywords: Nanorods Gadolinium oxide UV–vis Photoluminescence Thermoluminescence abstract Different phases of Eu 3+ activated gadolinium oxide (Gd (OH) 3 , GdOOH and Gd 2 O 3 ) nanorods have been prepared by the hydrothermal method with and without cityl trimethyl ammonium bromide (CTAB) surfactant. Cubic Gd 2 O 3 :Eu (8 mol%) red phosphor has been prepared by the dehydration of correspond- ing hydroxide Gd(OH) 3 :Eu after calcinations at 350 and 600 1C for 3 h, respectively. When Eu 3+ ions were introduced into Gd(OH) 3 , lattice sites which replace the original Gd 3+ ions, a strong red emission centered at 613 nm has been observed upon UV illumination, due to the intrinsic Eu 3+ transition between 5 D 0 and 7 F configurations. Thermoluminescence glow curves of Gd (OH) 3 : Eu and Gd 2 O 3 :Eu phosphors have been recorded by irradiating with gamma source ( 60 CO) in the dose range 10–60 Gy at a heating rate of 6.7 1C sec 1 . Well resolved glow peaks in the range 42–45, 67–76, 95–103 and 102–125 1C were observed. When g-irradiation dose increased to 40 Gy, the glow peaks were reduced and with increase in g-dose (50 and 60 Gy) results the shift in first two glow peak temperatures at about 20 1C and a new shouldered peak at 86 1C was observed. It is observed that there is a shift in glow peak temperatures and variation in intensity, which is mainly attributed to different phases of gadolinium oxide. The trapping parameters namely activation energy (E), order of kinetics (b) and frequency factor were calculated using peak shape and the results are discussed. & 2010 Elsevier B.V. All rights reserved. 1. Introduction Currently, nanomaterials have become important within the field of luminescence as they exhibit excellent optoelectronic properties. They have potential to be efficient phosphors in display applications like flat panel displays, solar energy converters, optical amplifiers, electroluminescent devices, photodiodes, bio-detec- tors, etc [1–4]. In particular, oxide nanophosphors (Gd 2 O 3 S:Eu, Ti, Mg, Y 2 O 3 :Eu 3+ and Gd 2 O 3 :Tb 3+ ) with the incorporation of activators have revealed major luminescence effects. In addition, various vacancies and defects of host materials result complicate luminescence centres as electron donors and acceptors and show potential to exhibit a wide variety of attractive luminescence features. Significant advancements have been made in thermolumines- cence (TL) experiments during last couple of decades on bulk materials. With the advent of nanotechnology, there is still a considerable amount of research for new nanocrystalline phosphor materials with better TL and dosimetric properties. The importance of nanocrystalline materials has increased tremendously because of the enhanced optical, electronic and structural properties than their bulk counterparts due to quantum size effect and an increased surface to volume ratio [5,6]. In order to use information about luminescence process of phosphors in various applications, the knowledge of defect centres and their distribution in the band gap of solids is very important. Further, it is also important for basic study to understand defects and reorganization of energy levels in nanostructured materials and related phenomena. One of the most sensitive methods of studying radiation induced defects is TL. It is well known that the defect centres created by ionizing radiations are intimately related to the process of TL. Thermoluminescence studies of nanocrystalline phosphors are important not only for application point of view. TL efficiency increases due to increase in the surface states which also increase on increasing the particle Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/physb Physica B 0921-4526/$ - see front matter & 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.physb.2010.10.013 n Corresponding authors. E-mail addresses: bhushanvl@rediffmail.com (H. Nagabhushana), sreechakra72@yahoo.com (R.P.S. Chakradhar). 1 Present address: Scientist, CSIR-NAL, Bangalore 560 017, India. Physica B 406 (2011) 1645–1652