Advances in Materials Physics and Chemistry, 2013, 3, 48-57 http://dx.doi.org/10.4236/ampc.2013.31008 Published Online March 2013 (http://www.scirp.org/journal/ampc) Cu- and Ni-Doping Effect on Structure and Magnetic Properties of Fe-Doped ZnO Nanoparticles Jefferson A. Wibowo, Nadia F. Djaja, Rosari Saleh * Departemen Fisika, FMIPA-Universitas Indonesia, Depok, Indonesia Email: * rosari.saleh@ui.ac.id, * rosari.saleh@gmail.com Received January 7, 2013; revised February 8, 2013; accepted February 18, 2013 ABSTRACT Cu- and Ni-codoped FeZnO particles with the wurzite structure were successfully synthesized at low temperature by a co-precipitation method. The samples were characterized using a vibrating sample magnetometer, X-ray diffraction, energy dispersive X-ray spectroscopy, UV-Vis spectrophotometry and electron spin resonance. The results demonstra- ted that room temperature ferromagnetic order was observed in both samples and the magnetization was higher than that of Fe-doped ZnO. The correlation between the structural and magnetic properties is discussed. Keywords: Codoped ZnO Nanoparticles; Room-Temperature-Ferromagnetic; Co-Precipitation 1. Introduction Dilute magnetic semiconductors (DMSs) in which some of the cations host lattice are replaced by a transition metal ions have attracted considerable attention due to their potential as spin-polarized carrier sources and their potential applications in spintronic devices [1-5]. The main challenge for practical application of DMSs is the attainment of Curie temperature above room tempera- ture [6]. Following the theoretical prediction of room temperature ferromagnetic by Dietl et al. [7], several studies involving magnetic ions doped II-VI semicon- ductors were performed by different researcher in tran- sition metal doped ZnO. It is known that ZnO has high solubility for transition metals and superior semicon- ductor properties [8]. Moreover, ZnO is a wideband gap semiconductor with a relative large exciton binding en- ergy. Among transition metal, ZnO doped with Fe ions without any modification of the structure has been the most considerable interest. Ferromagnetism with Curie temperature higher than room temperature has been ob- served in Fe-doped [9-12], Co-doped [13-15], Mn-doped [16-18], Ni-doped [19-21], Cu-doped [22] and V-doped [23] ZnO nanoparticles. Meanwhile, several codoped ZnO have also been reported with the expectation that codoping can lead to remarkable changes in the proper- ties of the materials [24-26]. Presence of two different kind of transition ions simultaneously in a host material produces magnetic property that can be different from the magnetic property due to single transition metal ions. For instance, Han et al. [27] reported that the Curie tem- perature of bulk Zn 0.94 Fe 0.05 Cu 0.01 O was above room temperature and the maximum saturation of magneti- zation was larger than that of the sample without Cu [27,28]. Shim et al. [29] also prepared FeCu co-doped ZnO sample and reported that the room temperature fer- romagnetic in the sample is due to the secondary phase ZnFe 2 O 4 [27,29]. Despite the considerable amount of data a great deal of controversy remains, especially regarding the fundamen- tal issue of whether the system actually exhibits room temperature ferromagnetic at all; and in the case where it does, whether the effect is intrinsic to the material. Fur- ther studies suggested that the inconsistencies in the lit- erature regarding the ferromagnetic ordering of transition metal doped ZnO indicate that these materials are very sensitive to the fabrication and processing conditions. Therefore, this paper we attempt to study the effect of Cu- and Ni co-doping on the weakest ferromagnetic Fe- doped ZnO (1 at% of Fe). The co-precipitation method was chosen for the synthesis of these materials because it is cost effective, requires low temperature processing and offers a higher degree of solubility. The effects of Cu and Ni doping on the structural, optical and magnetic proper- ties of nanocrystalline Fe-doped ZnO particles was in- vestigated using X-ray diffraction (XRD), energy disper- sive X-ray (EDX), UV-Vis spectroscopy (UV-Vis), elec- tron spin resonance (ESR) and vibrating sample magne- tometer (VSM). It was found that the incorporation of Cu and Ni in Fe-doped ZnO nanoparticles not only enhances ferromagnetic properties to the host materials but also changes lattice constant and the optical properties. * Corresponding author. Copyright © 2013 SciRes. AMPC