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A B S T R A C T S WEDNESDAY, JUNE 30 N A N O S E A 2 0 1 0 2 – Abstract We report on the occurrence of enhanced photoluminescence and room temperature ferromagnetism in Codoped ZnO nanoparticles (NPs). Doping is performed by ball milling of 3 wt% of Co mixed with ZnO nanopowders (commercial) for durations of 2-8 hrs. X-ray diffraction data and high resolution transmission electron microscopy (HRTEM) confirm the absence of metallic Co clusters or any other phase different from würtzite-type ZnO. The field dependence of magnetization (M–H curve) measured at room temperature exhibited the clear ferromagnetic characteristic with saturation magnetization (Ms) and coercive field (Hc) of , respectively. Post- -visible absorption spectra show red-shift in the absorption peaks in the Co doped ZnO NPs indicating incorporation of Co atoms in ZnO lattice. Room temperature photoluminescence studies show enhanced near-band-edge emission at 378 nm in the doped NPs as compared to the undoped ZnO NPs indicating negligible presence of defects in the doped ZnO crystals. This work demonstrates the feasibility of large scale production of ferromagnetic semiconductors that are potentially useful for building nanoscale spintronic devices. 3 – Conclusion We have achieved Co doping of ZnO nanoparticles by planetary ball milling technique. Structural analysis confirm the absence of metallic Co clusters or any other phase different from würtzite-type ZnO. We observed clear room temperature ferromagnetism with saturation magnetization (Ms) and coercive field (Hc) of the order o systematically and it is concluded that defects do not play any significant role in the FM of CoZnO. We also observed enhanced PL emission in the Co doped ZnO NPs. 12H20-12H40 Study of Composition, Structure and Optical Properties of Nano-structured ZnS:Mn Thin Films Prepared by Chemical Deposition Method. Alireza Goudarzia, Reza Sahraeib ,Chang-Sik Hac,* (aDept.of Polymer Engineering, Golestan University,Gorgan,Iran.,bDept.of Chemistry, University of Ilam, Ilam, cPolymer Science and Engineering Pusan National University, Busan 609-735,Republic of Korea) csha@pusan.ac.kr 1 – Introduction: Zinc sulfide is a semiconductor suitable for use as a host matrix for a wide variety of dopants on account of its wide energy band gap. The luminescent properties of this material doped with Mn have proven to be suitable for electroluminescence applications. Manganese is generally incorporated as Mn2+ ion in the substitutional sites of the ZnS lattice. ZnS:Mn films, however, have been usually prepared by expensive and difficult (strict) methods. Doping zinc sulfide with manganese is usually made by thermal diffusion of Mn salt at high temperature, such as, for example, spray pyrolysis method1,2. In this work, we report the preparation of Mn2+ doped ZnS thin films by chemical bath deposition (CBD) method at different temperatures and Mn2+ concentrations. The CBD method is simple, convenient and cost effective because it is normally carried out at atmospheric pressure (usually in air) and near ambient temperatures. It has the advantage of not requiring vacuum systems and is compatible with large area deposition. 2 – Abstract 77
A B S T R A C T S WEDNESDAY, JUNE 30 N A N O S E A 2 0 1 0 In this work, ZnS:Mn thin films were deposited on quartz, Si (polycrstal), and glass substrates using a CBD method in an aqueous solution containing ethylene diamine tetra acetic acid disodium salt (Na2EDTA) as the complexing agent for zinc ions and TAA as the sulfide source at different temperatures. ZnS: Mn thin films with thicknesses ranging from 60 to 450 nm were synthesized at various Mn2+/Zn2+ molar ratios ranging from 1 to 4. The effects of the process parameters on the properties of ZnS:Mn films were investigated. The films were characterized by energy dispersive X-ray spectrometer (EDX), inductively coupled plasma atomic emission spectroscopy (ICP-AES), secondary ion mass spectrometry (SIMS), X-ray diffractometer (XRD), high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FE-SEM), ultra violet –visible light (UV-Vis) spectroscopy, and photoluminescence (PL) spectroscopy. 3 – Conclusion The results showed that the deposition time, deposition temperature, and Mn doping concentration can affect the composition, surface morphology, crystallinity, thickness, grain size, and hence the photoluminescence and transmission spectra of the films. The SIMS and Photoluminescence studies revealed the presence of two kinds of Mn in ZnS:Mn films that exhibit their own characteristic emissions. 1)Hernández-Fenollosa, M. A., et al., Thin Solid Films 2008, 516, 1622. 2)López, M. C.,et al., J. Crys. Grow. 2005, 285, 66. 78
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