Morphological control of MnSe 2 /Se nanocomposites by amount of hydrazine through a hydrothermal process Azam Sobhani a , Masoud Salavati-Niasari a,b, * a Department of Inorganic Chemistry, Faculty of Chemistry, University of Kashan, P.O. Box. 87317–51167, Kashan, Islamic Republic of Iran b Institute of Nano Science and Nano Technology, University of Kashan, P.O. Box. 87317–51167, Kashan, Islamic Republic of Iran 1. Introduction Synthesis of metal chalcogenide semiconductor nanocrystals in controllable shape and size is of great significance for modern science and technology. Transition metal dichalcogenides MX 2 (M = Mn, Fe, Co, Ni; X = S, Se) with pyrite structures have been paid much attention due to their electrical, magnetic, and optical properties [1–5]. A great number of experimental and theoretical studies have been reported on the so-called pyrites MX 2 during the last decades [6–9], Due to their application in rechargeable battery electrodes [10] and dilute magnetic semiconductors (DMSs) [11]. The pyrites MX 2 are very attractive to scientists. Recently, many studies have intensely focused on DMSs due to their special physical properties and potential applications such as blue/green light emitters [12]. In particular, manganese selenides (e.g. MnSe 2 , MnSe) possess strong sp–d band electrons exchange interactions between electron/hole band states and Mn 2+ 3d electron states for the introducing of Mn 2+ ions [13,14]; therefore they have unique critical magnetic function and can be used to fabricate DMSs [15]. Additionally, MnSe 2 and MnSe have received increasing interest for their important electrical, magneto-optical, and transport properties and potential applications in such areas as solar cells, infrared detectors and spintronic devices [16,17]. These properties show a considerable increase in MnSe 2 /Se nanocomposites compared to the MnSe 2 . The aim of making the composite nanomaterials in this study was to improve the properties and applications of the MnSe 2 . Traditionally, molecular beam epitaxy (MBE) [18], organome- tallic vaporphase epitaxy (OMVPE) [19], solution-phase synthesis [20], reaction metal Mn with elemental Se [21], hydrothermal [22– 26] and solvothermal process [27] were employed to synthesize manganese selenides. These methods usually need complex apparatus, severe reaction conditions, high temperature or toxic raw materials, which may restrict the large-scale preparation of the materials. In this paper, by using SeCl 4 and MnCl 2 Á4H 2 O as starting materials, we have successfully grown MnSe 2 /Se nanorods on surfaces of microcubes remarkably, under hydrothermal condi- tions. The hydrothermal involves heating of reactants in a particular solvent in a high-pressure system such as an autoclave. This method is simple, convenient and effective controlled synthetic procedure and provided an effective way to the synthesis of selenides and tellurides materials. In our group, for a few years, we have been interested in the synthesis of metal telluride and selenide nanostructures and development of the semiconductors is the major interest [28–30]. Using of the novel compound can be useful and open a new way for preparing metal selenide semiconductors to control nanocrystal size, shape and distribution size. SeCl 4 was selected in our experiments to provide a highly reactive selenium source in aqueous solution and has been lead to Materials Research Bulletin 48 (2013) 3204–3210 A R T I C L E I N F O Article history: Received 17 October 2012 Received in revised form 9 April 2013 Accepted 29 April 2013 Available online 15 May 2013 Keywords: A. Chalcogenides A. Nanostructures A. Semiconductors B. Chemical synthesis C. X-ray diffraction A B S T R A C T MnSe 2 /Se nanocomposites have been successfully synthesized through a hydrothermal process by using SeCl 4 and MnCl 2 Á4H 2 O as starting materials, in presence of polyethylene glycol 600 (PEG 600) and hydrazine (N 2 H 4 ÁH 2 O) as surfactant and reductant, respectively. It was found that hydrazine concentration has significant effect on morphology and phase of the final products. The possible formation mechanism of different morphologies was briefly proposed. This work has provided a general, simple, and effective method to control the composition, phase structure and morphology of metal selenides in aqueous solution, which will be important for inorganic synthesis methodology and further applications of selenides. ß 2013 Elsevier Ltd. All rights reserved. * Corresponding author. Tel.: +98 361 591 2383; fax: +98 361 555 2930. E-mail address: salavati@kashanu.ac.ir (M. Salavati-Niasari). Contents lists available at SciVerse ScienceDirect Materials Research Bulletin jo u rn al h om ep age: ww w.els evier.c o m/lo c ate/mat res b u 0025-5408/$ – see front matter ß 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.materresbull.2013.04.086