Investigation of the optical properties of Mg(OH)2 and MgO nanostructures obtained by microwave-assisted methods

► Two new methods for the synthesis of nano Mg(OH)2 and MgO are described. ► Mg(OH)2 was prepared by a simple reaction of Mg powder with H2O under microwave. ► Mg(OH)2 transformed into MgO nanoflakes by rapid microwave hybrid heating. ► SiC-based composite was used as a microwave heater. ► Optical properties of nano Mg(OH)2 and MgO were investigated. Two simple methods for the synthesis of Mg(OH)2 nanostructures, MgO nanoflakes and MgO/Mg(OH)2 nanocomposite using a conventional microwave oven are reported. The first method includes the preparation of Mg(OH)2 by a simple reaction of magnesium powder with deionized water under microwave radiation. The second approach relates to the transformation of Mg(OH)2 to MgO nanoflakes and grass-like nanostructures by rapid microwave hybrid heating using a SiC-based composite susceptor. The as-synthesized samples have been characterized by X-ray diffraction (XRD) and Field Emission Scanning Electron Microscope (FESEM) The optical properties of the samples are investigated using UV–visible spectroscopy to study the reflective index and optical dielectric constant.