SOL-GEL PREPARATION AND CHARACTERIZATION OF MAGNESIUM PEROXIDE, MAGNESIUM-HYDROXIDE METHOXIDE, AND RANDOMLY AND (111) ORIENTED MGO THIN-FILMS

A H2O2-assisted sol-gel method for the preparation of precursors for f ormation of thin films of MgO is described. Sols were prepared from th e addition of Mg(OCH3)(2) to methanolic H2O2. Two such sols, with Mg t o H2O2 ratios of 1:1 and 1:10, were used to prepare, respectively, ran dom or (111) oriented MgO thin films on Si(100). The xerogel from a so l with a 1:10 Mg:H2O2 ratio contained nanocrystalline MgO2 . nH(2)O, w hereas the xerogel from a comparable sol with a 1:1 Mg:H2O2 ratio cont ained nanocrystals of MgO2 . nH(2)O, and Mg(OH)(OCH3). The latter comp ound was the hydrolysis product of methanolic Mg(OCH3)(2) even when tr eated with up to 4 equiv of water. The thermal decomposition propertie s of this compound are reported. Using the published method of treatin g Mg(NO3)(2) with excess 30% H2O2, MgO2 . nH(2)O, with a Mg2+:O-2(2-) ratio of 1:0.74, was prepared. Based on IR, TGA, and DTA results, it i s proposed that the material also contained oxide, and possibly hydrox ide ions for charge balance. These ions were present either in an amor phous phase, or possibly substituted for O-2(2-) in the MgO2 crystal s tructure.