Synthesis, characterization and optical properties of Mg(OH)2 micro-/nanostructure and its conversion to MgO

Magnesium hydroxide (Mg(OH)2) micro- and nanostructures have been synthesized by a single step hydrothermal route. Surface morphology analysis reveals the formation of micro- and nanostructures with varying shape and size at different synthesis conditions. Structural investigations by X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirm that the synthesized material is Mg(OH)2 with hexagonal crystal structure. An optical band gap of 5.7 eV is determined for Mg(OH)2 nanodisks from the UV–vis absorption spectrum. A broad emission band with maximum intensity at around 400 nm is observed in the photoluminescence (PL) spectra of Mg(OH)2 nanodisks at room temperature depicting the violet emission, which can be attributed to the ionized oxygen vacancies in the material. Furthermore, Mg(OH)2 has been converted to MgO by calcination at 450 °C. Optical studies of the MgO nanodisks have shown an optical band gap of 3.43 eV and a broadband PL emission in the UV region. Mg(OH)2 and MgO nanostructures with wide-band gap and short-wavelength luminescence emission can serve as a better luminescent material for photonic applications.