Journal of Alloys and Compounds 506 (2010) 249–252 Contents lists available at ScienceDirect Journal of Alloys and Compounds journal homepage: www.elsevier.com/locate/jallcom Temperature dependence of morphology, structural and optical properties of ZnS nanostructures synthesized by wet chemical route M. Navaneethan a,c , J. Archana a , K.D. Nisha b , Y. Hayakawa c , S. Ponnusamy a,∗ , C. Muthamizhchelvan a a Center for Materials Science and Nano Devices, Department of Physics, SRM University, Kattankulathur 603 203, Kancheepuram (D.t), Tamil Nadu, India b Department of Physics, Asan Memorial College of Engineering and Technology, Chengalpattu 603105, Tamil Nadu, India c Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu, Shizuoka 432-8011, Japan article info Article history: Received 24 March 2010 Received in revised form 23 June 2010 Accepted 1 July 2010 Available online 7 July 2010 Keywords: Nanostructured materials Optical materials Semiconductors Chemical synthesis Luminescence abstract ZnS nanostructures have been synthesized by simple wet chemical route and annealed at two differ- ent temperatures of 50 ◦ C and 180 ◦ C. From the measurements of transmission electron microscopy and contact-mode atomic force microscopy, it is found that annealed temperature changes the morphology from nanoparticles to nanorods. The optical properties of the synthesized ZnS nanomaterial have been characterized by UV–visible absorption spectroscopy and photoluminescence spectroscopy. The struc- tural and elemental analyses were carried out by powder X-ray diffraction pattern and energy dispersive X-ray absorption spectroscopy, respectively. Absorption edge of the nanoparticles (295 nm) and nanorods (326 nm) was shifted towards shorter wavelength compared to bulk ZnS (337 nm) due to the quantum confinement effect. © 2010 Elsevier B.V. All rights reserved. 1. Introduction In the past decade, semiconducting nanoparticles have received a considerable attention because of their excellent size depen- dent electrical and optical properties suitable for applications in optoelectronic devices [1,2]. Since the optical band gap of these semiconductors can be tuned by varying the size of the parti- cles, these tuned optical properties of the materials have potential applications in the field of solar cell [3], light emitting diode [4], telecommunications [5], etc. Among the semiconducting particles, II–VI binary semiconductors are widely used in technological appli- cation. In particular, ZnS has a wide band gap of 3.68 eV, it is widely used in cathode ray tubes and field emission display [6], electrolu- minescent devices [7] and photodiodes [8]. Several methods have been adopted for the synthesis of nanoparticles, such as wet chem- ical method [9], microwave irradiation [10], micro emulsion [11], chemical vapor deposition [12], etc. ZnS can be synthesized by dif- ferent routes, such as chemical route, microwave irradiation, etc. In the present work, ZnS nanostructures were synthesized by wet chemical route without non toxic precursors annealed at two different temperatures. Surface morphology and structural property have been measured by atomic force microscopy (AFM), transmission electron microscopy (TEM) and X-ray diffraction ∗ Corresponding author. Tel.: +91 44 27452818; fax: +91 44 27456255. E-mail address: suruponnus@gmail.com (S. Ponnusamy). (XRD). The optical properties of the synthesized materials were investigated by ultra violet (UV) spectrophotometer and photo- luminescence (PL) spectrophotometer. The elemental analysis has been performed by energy dispersive X-ray spectroscopy (EDAX). 2. Experimental All chemicals used were of analytical grade without further purification. ZnS nanoparticles were synthesized using zinc acetate and thioacetamide as source materials. 0.2 M Zinc acetate and 0.2 M thioacetamide were dissolved in 50 ml of ethanol and stirred at a constant rate for 8 h. This resulted in a milky white solu- tion, indicating the formation of ZnS. Subsequently, the resulting milky white solid products were centrifuged and washed using ethanol. Finally, a part of the product (sample A) was dried at temperature of 50 ◦ C for 10 h and remaining part (sample B) was dried at 180 ◦ C in hot air oven for 10 h. AFM studies were carried out with Pico Scale SPM (Molecular Imaging, USA). TEM images were taken with JEM 3010(JEOL) TEM with an accelerating voltage of 200 keV. X-ray diffraction (XRD) pattern was recorded using X’perPRO (PANalytical) advanced X-ray diffractometer with CuK1 radiation ( = 1.5406 Å), with 2 ranging between 20 ◦ and 80 ◦ at a scanning rate of 0.5 ◦ /s. Absorption spectrum was mea- sured using PerkinElmer lambda 5 UV–visible spectrophotometer. PL spectrum was obtained using Flurolog-3 spectrophotometer (Jobin Yvon) in the range 200–900 nm. EDAX analysis was performed by Hitachi S 3400 SEM working at 25 kV accelerating voltage. Ethanol was used as a medium to prepare the sample for UV, PL, AFM and TEM studies. 3. Results and discussion Fig. 1(a) shows the AFM image of sample A annealed at tem- perature of 50 ◦ C and it reveals the formation of nanoparticles. In this image, all the particles exhibited uniform size and spherical 0925-8388/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2010.07.002