Cryst. Res. Technol. 44, No. 2, 153 – 158 (2009) / DOI 10.1002/crat.200800271 © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Synthesis and characterization of nano ZnS doped with Mn P. Vinotha Boorana Lakshmi, K. Sakthi Raj, and K. Ramachandran* School of Physics, Madurai Kamaraj University, Madurai, Tamil Nadu-625021, India Received 3 April 2008, revised 29 May 2008, accepted 24 July 2008 Published online 25 August 2008 Key words diluted magnetic semiconductors, X-ray diffraction, EPR, ferromagnetism. PACS 61.46.+w, 61.10.-I, 76.30.-v, 76.50.+g Nanocrystalline samples of Zn 1-x Mn x S (x = 0.0, 0.02, 0.04) were synthesized by chemical precipitation method and characterized for magnetism. EPR studies showed an evidence of ferromagnetism around room temperature. Hysterisis from vibrating sample magnetometer supports the observation. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 Introduction Zinc sulphide (ZnS), a II-VI semiconductor with a direct band gap of 3.6eV at room temperature and 40meV as exciton binding energy, is a very good luminescence material used in displays, sensors and lasers apart from applications in photocatalysis [1,2]. Nanodimensional ZnS is found to exhibit excellent optical and optoelectronic properties which differ greatly from the bulk ZnS [3-5]. ZnS doped with Mn is also an equally important electroluminescent material. Bhargava et al. [6] first reported luminescence properties of Mn-doped ZnS nanocrystals prepared by a chemical process at room temperature, which initiated investigation on this topic [7-9]. However, when magnetic Mn 2+ ions are introduced into nanoparticles of nonmagnetic ZnS semiconductor, then interesting magnetic and magneto-optical properties are imminent. Wang et al. [10] observed spin-glass behaviour at T c = 15 K in Zn 1-x Mn x S at a high concentration x = 0.32 but a paramagnetic behaviour at a low concentration x = 0.16. Heidrich [11] concluded that there is an antiferromagnetic coupling at the Neel temperature of T N =152 K ,whereas Tsujii et al. [12] found no antiferromagnetic behaviour in ZnS:Mn systems. Yuan et al. [13] reported paramagnetic behaviour in ZnS:Mn nanosystems prepared by co-precipitation method. Apart from these, there is not much work on ZnS:Mn, particularly, on magnetic properties and most of the papers are focused on the efficient luminescent properties. Even the reported magnetic works on ferromagnetism are in the cryogenic temperature. After the work of Dietl et al. [14] attention is towards finding new spintronic materials exhibiting room temperature ferromagnetism. Keeping this mind, the present work on ZnS:Mn nanosystem was carried out. 2 Synthesis Although various methods are available for the synthesis of nano ZnS, chemical precipitation is widely being used for the preparation of colloidal nanoparticles as the possibility of cluster formation is very less in this method when compared to the other methods. Here, 0.5126 M ZnSO 4 solution and 0.069 M Na 2 S solution were prepared in deionized water and were first refluxed for an hour separately. 6 ml Na 2 S solution was then added to the 50 ml ZnSO 4 , which was continuously refluxed to get a colloidal form of ZnS. The colloidal sample was refluxed for another 20 min at 80°C for uniform distribution of the particles. Then this was filtered out and washed with distilled water and ethanol for removing the additional impurities formed during the preparation ____________________ * Corresponding author: e-mail: : thirumalchandran@yahoo.com