Optical properties of MgO and Mg(OH)2 nanostructures synthesized by a chemical precipitation method using impure brine

In the current study, synthesis of Mg(OH)2 nanostructures from the CaCl2-MgCl2-NaCl-KCl-H2O system under controlled conditions using chemical precipitation method and also their transformation into MgO nanoparticles are reported. Field emission scanning electron microscopy (FESEM) results indicated that the morphology of Mg(OH)2 and MgO nanopowders are in forms of aggregated nanosheets and nanoparticles, respectively. The temperature range of transforming magnesium hydroxide nanostructures into magnesium oxide nanoparticles was determined through the thermal gravity analysis (TGA). Moreover, the characterization through x-ray diffraction (XRD), energy dispersive x-ray spectroscopy (EDAX) and Fourier transform infrared spectroscopy (FTIR) implied that synthesized products are crystallized as well and they lack any defects. Finally, their optical properties were investigated by UV-visible and then the optical band gap of 5.4 eV and 4.6 eV were obtained for Mg(OH)2 and MgO, respectively.