Synthesis of ZnO and ZnS nanocrystals by thermal decomposition of zinc(II) cupferron complex P. Saravanan * , Sarfaraz Alam, G.N. Mathur Defence Materials and Stores Research and Development Establishment, DMSRDE P.O., G.T. Road, Kanpur 208 013, India Received 8 January 2004; received in revised form 25 May 2004; accepted 29 May 2004 Available online 2 August 2004 Abstract A non-hydrolytic single-molecular precursor approach to dispersable nanocrystals of ZnO and ZnS by means of thermal decomposition of zinc(II) Cupferron complex (ZnCup 2 ) in alkylamines, using suitable reaction atmosphere is reported. The obtained ZnO and ZnS nanocrystals were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV–Vis spectroscopy. Structural and optical studies on these semiconductor nanocrystals apparently reveal that the decomposition of ZnCup 2 under Ar atmosphere can yield ZnO nanocrystals; on the other hand, ZnS nanocrystals can be obtained under H 2 S atmosphere. D 2004 Elsevier B.V. All rights reserved. Keywords: Nanomaterials; Semiconductor; Nanocrystals; Cupferron complex; ZnO; ZnS 1. Introduction Among all the semiconductor nanocrystals, zinc oxide, as well as zinc sulphide have been intensively studied during the past years due to their envisaged applications in many technologies, such as optoelectronic devices, gas sensors, solar cells and catalysis [1]. Therefore, a great deal of attention has been focused on the preparation of ZnO nanocrystals employing numerous synthesis techniques including, the solution method [2], evaporation–condensa- tion [3] solid-state thermal decomposition of the precursor [4] and ultrasonic irradiation [5]. Similar methods have also been employed for the synthesis of ZnS nanocrystals [6]. Recently, the use of single-molecular precursors has been widely reported in literature for preparing nano- crystals of metal-chalcogenides. Pickett and O’Brien successfully demonstrated the preparation of chalcogenide nanoparticles using the precursor: M(E 2 CNR 2 ) 2 ; (M=Zn or Cd, E=S or Se, and R=alkyl) [7]. Lieber et al. utilized Cd(S 2 CNEt 2 ) 2 and Zn(S 2 CNEt 2 ) 2 as single-molecular precursors for the growth of CdS and ZnS nanowires by using a nanocluster-catalyzed vapor–liquid–solid mecha- nism [8]. Kim et al. reported the synthesis of ZnO nanocrystals by the thermolysis of (EtZnO i Pr) as a single- molecular precursor and trioctylphosphine oxide (TOPO), without any extra solvent as well as any oxygen source [9]. In this context, it has also been suggested that metal Cupferron complexes M x Cup x (M: metal ion; Cup: N- nitrosophenylhydroxylamine, C 6 H 5 N(NO)O À ), could be used as single-molecular precursors in the synthesis of respective metal oxide nanocrystals [10]. In this non- hydrolytic route, the Cupferron complex (which binds to the metal ion through oxygen) is decomposed, releasing a leaving group such as, nitrosobenzene at 250À300 8C in hot coordinating solvent. Developments in the synthesis of high quality oxide nanocrystals such as, g-Fe 2 O 3 , MnO, Cu 2 O [10] and Fe 3 O 4 [11] have demonstrated the potential of this non-hydrolytic approach, by means of thermal decomposition of their respective metal Cupferron complexes. In this work, we have extended this approach to synthesize both ZnO and ZnS nanocrystals by the thermal decomposition of zinc(II) Cupferron complex (ZnCup 2 ) in the presence of n -octylamine as surfactant. This investigation enables one to synthesize dispersable 0167-577X/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2004.05.084 * Corresponding author. Tel: +91 512 2451761; fax: +91 512 2450404. E-mail address: sar-p@mailcity.com (P. Saravanan). Materials Letters 58 (2004) 3528 – 3531 www.elsevier.com/locate/matlet