Methylmagnesium Alkoxide Clusters with Mg4O4 Cubane- and Mg7O8 Biscubane-Like Cores: Organometallic Precursors for Low-Temperature Formation of MgO Nanoparticles with Variable Surface Defects

摘要

Nanocrystalline MgO powders with variable surface defect concentrations are simply accessible by solid-state thermolysis at relatively low temperatures utilizing the molecular single-source precursors (SSPs) [MeMgOR]₄ (R = iPr, tBu, CyHex) and the first bis-cubanes Me₆Mg₇(OR)₈ (Et, Pr, Bu). The decomposition conditions including heating rates, tempering times, and atmospheres have been varied, and the structure and purity of the obtained samples were analyzed by means of different analytical techniques (TGA, PXRD, TEM, EDX, elemental analysis and BET measurements). The crystal sizes vary from approximately 8 to 15 nm depending on the heating rates, tempering times and nature of the applied SSP. Photoluminescence spectroscopy (PLS) of the samples suggests the presence of defects, which could be attributed to different surface oxide sites of the MgO particles depending on the thermolysis conditions, in particular the heating rate and tempering time.