Synthesis of nanocrystalline MgH_2 powder by gas-phase condensation and in situ hydridation: TEM, XPS and XRD study

摘要

In this work, a two-step method for the preparation of nanocrystalline MgH_2 is presented, where the first step consists of synthesis of nanocrystalline Mg powder by the gas-phase condensation method (GPC) and the second of in situ hydridation leading to the formation of MgH_2 nanoparticles. By transmission electron microscopy (TEM) and electron diffraction (ED), crystalline Mg nanoparticles from GPC were found to have mean size within the range of 30-50 nm, while in the case of MgH2 nanoparticles these values increase approximately 2-3 times mainly due to particles growth during the hydridation step. The X-ray diffraction (XRD) analysis shows the high conversion into the MgH_2 phase after hydridation. By X-ray photoelectron spectroscopy (XPS) metallic magnesium was detected below a magnesium oxide layer of 3-4 nm for the Mg sample prepared by GPC, which shows the efficiency of a novel sample transfer system without air exposure between N2-glove-box, preparation chamber and experimental apparatus.