Materials Chemistry and Physics 125 (2011) 872–875 Contents lists available at ScienceDirect Materials Chemistry and Physics journal homepage: www.elsevier.com/locate/matchemphys Synthesis of Mn doped ZnO nanocrystals by solvothermal route and its characterization S. John Kennady Vethanathan a , M. Brightson b , S. Meenakshi Sundar c,∗ , S. Perumal d a St. John’s College, Palayamkottai, India b St. Jude’s College, Thoothoor, India c Sri Paramakalyani College, Alwarkurichi, India d S. T. Hindu College, Nagercoil, India article info Article history: Received 19 December 2009 Received in revised form 16 September 2010 Accepted 19 September 2010 Keywords: Dilute magnetic semiconductors Microwave solvothermal synthesis Electron paramagnetic resonance abstract Undoped and Manganese doped Zinc Oxide were prepared by solvothermal technique. The structural analysis was carried out using X-ray diffraction. It showed that the undoped Zinc Oxide and Manganese doped Zinc Oxide nanocrystals to exhibit hexagonal wurtzite structure. Grain sizes were estimated from Atomic Force Microscopy and Transmission Electron Microscopy images. The surface morphological stud- ies from Scanning Electron Microscope, Transmission Electron Microscope and Atomic Force Microscope depicted spherical particles with formation of clusters. The magnetic behavior studied by Vibrating Sam- ple Magnetometer indicated paramagnetic behaviour. Hyperfine splitting is observed using Electron Spin Resonance studies. © 2010 Elsevier B.V. All rights reserved. 1. Introduction The semiconductor ZnO has gained substantial interest in the research community in part because of its wide band gap energy (3.3 eV), eco friendly, transparency, etc. The interest in ZnO is fueled and fanned by its prospects in optoelectronics applications owing to this wide direct band gap energy. Dilute Magnetic Semicon- ductors have attracted a great deal of attention in the past few years as enabling materials in the emerging field of spintronics [1]. It focuses on spin dependent phenomena applied to mod- ern electronic devices. DMS which combine the two interesting properties; magnetic and semiconducting are considered as an ideal system for spintronics [2,3]. DMS are semiconductor solid solutions where a small percentage of cations are replaced by mag- netic impurities such as Mn. Due to the host sp-Mn d interactions in these DMSs, unusual magnetotransport and magneto optical behavior have been observed [2]. Among the DMSs, Mn doped II–VI compounds have been extensively studied. ZnO (diamagnetic) is one of the host oxide to which addition of Mn causes paramag- netic or ferromagnetic depending on the concentration of ‘Mn’, type and concentration of charge carriers [4], preparation methods and processing temperature conditions. The ionic radius of Mn 2+ (0.66 ˚ A) is relatively close to that Zn (0.60 ˚ A), suggesting moder- ate solid solubility without phase segregation [5]. Furthermore, ∗ Corresponding author. Tel.: +91 9442066199. E-mail address: smsun 1964@yahoo.co.in (S.M. Sundar). Mn was assumed to be a deep donor in ZnO with energy levels, 0.4 eV, 0.7 eV or 2.0 eV below the conduction band edge at room temperature [6]. Many researchers have worked on Mn doped ZnO as bulk crys- tals and thin films keeping different views. Kim et al. [2] have studied the change in the microstructure and growth behaviour of Mn doped ZnO films epitaxially grown on Al2O 3 substrates by PLD. Jin et al. [7] have fabricated epitaxial thin films of Zn x Mn 1-x O (x < 0.22) by combinatorial laser molecular beam epitaxy method to study the blue and ultraviolet luminescence from this system. Fukumura et al. [8,9] have obtained epitaxial thin films of Mn doped ZnO by pulsed laser deposition, with Mn substitution as high as 35%, while maintaining the wurtzite structure. Sharma et al. [10] have observed ferromagnetism above room temperature in both bulk and thin film forms of Mn doped ZnO. Mn doped ZnO nanocrystals were synthesized by a co-precipitation method by Paul Joseph et al. [11]. The magnetic properties of ZnO DMS are highly sensitive to the method of preparation and processing conditions. It has been pre- pared by a variety of methods, in this paper we prepare ZnO:Mn by a novel solution phase method employing microwave irradia- tion. Recently microwave irradiation has been found to be a fast and effective technique to the formation of nano particles [12–15]. Microwave heating has unique effects compared with the conven- tional heating, such as rapid volumetric heating, selective heating and energy saving considerations. These effects make microwave heating a promising technology that can increase reaction rates, shorten reaction time and enhance reaction selectivity. 0254-0584/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.matchemphys.2010.09.029