Structural properties of Zn_1-xMg_xO nanomaterials prepared by sol-gel method

The mixed oxides Zn_1-xMg_xO (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 × < 0.25, Mg replaces Zn substitutionally yielding ZMO single phase, while for × ≥ 0.25 two phases are identified ZMO and MgO. Replacing Zn2+ by Mg²⁺ 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 Mg²⁺ 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.