Cryst. Res. Technol. 44, No. 8, 845 – 850 (2009) / DOI 10.1002/crat.200900101 © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Structural properties of Zn 1-x Mg x O nanomaterials prepared by sol-gel method Z. K. Heiba* 1 and L. Arda 2 1 Ain Shams University, Faculty of science, physics department, Cairo, Egypt 2 Bahcesehir University, Faculty of arts and sciences, Besiktas, 34100, Istanbul, Turkey Received 20 February 2009, accepted 8 May 2009 Published online 12 June 2009 Key words nanomaterials, ZnMgO, microstructure. PACS 81.20.Fw The mixed oxides Zn 1-x Mg x O (ZMO) were prepared as nano-polycrystalline powders and thin films by a simple sol–gel process and dip coating method. Thermogravimetric (TG) and differential thermal analysis (DTA) were used to study the thermal chemistry properties of dried gel. Structural and microstructural analysis was carried out applying x-ray diffraction (XRD) and Rietveld method. Analysis showed that for x < 0.25, Mg replaces Zn substitutionally yielding ZMO single phase, while for x ≥ 0.25 two phases are identified ZMO and MgO. Replacing Zn 2+ by Mg 2+ distorts the cation tetrahedrons and decreases the lattice constants ratio c/a of the wurtzite ZMO which deviate the lattice gradually from the hexagonal structure as Mg 2+ increases. These distortions are attributed to the difference in electronic configuration of the two cations which suppress the paraelectric-ferroelectric phase transition in the ZMO wurtzite. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 Introduction Recently, there has been a great deal of interest in the physical properties of diluted magnetic semiconductors (DMSs) for their potential technological applications to optoelectronics, magnetoelectronics, and microwave devices. The substitution of the cations of III–V or II–VI nonmagnetic semiconductors by magnetic transition- metal ions such as Mn, Fe, and Co allows the existence of charge and spin degree of freedom in a single substance [1], which leads to a number of magnetic, optical, and magneto-transport phenomena. The development of magnetic semiconductors with practical ordering temperatures could lead to new classes of device and circuits, including spin transistors, and ultradense nonvolatile semiconductors memory [1–4]. The wurtzite-type Mg x Zn 1-x O alloys possess attractive properties for possible applications in optoelectronic and display devices. Alloying of wurtzite ZnO [5] with cubic MgO [6] results in metastable wurtzite (x <0.5) or zincblende (x > 0.5) crystals [7]. Wurtzite ZnO and Mg x Zn 1-x O crystals are uniaxial with ordinary and extraordinary dielectric functions. From recent optical studies of Mg x Zn 1-x O the energies of the fundamental band-to-band transitions were found to be strongly blue shifted with increasing Mg content [7–10]. Spectroscopic ellipsometry (SE) studies of Mg x Zn 1-x O in the transparency and E 0 -band-gap region were reported by Kang et al. [11]. The ordinary and extraordinary refractive indices and the properties of the fundamental band-gap region (E 0 -transitions) including energies of the band-to-band transitions, free exciton binding energy and broadening parameters of c-plane were determined [8]. In order to extend the band gap energy so as to achieve the true blindness, the Mg content in ZnMgO must be high. Magnesium oxide (MgO) has a band gap of 7.8 eV and cubic crystal structure. The ionic radius of Mg 2+ (0.57 Å ) is similar to that of Zn 2+ (0.60 Å) [11], so replacement of Zn by Mg should not cause a significant change in lattice constants. By ____________________ * Corresponding author: e-mail: zein_kh@yahoo.com