The preparation of molybdenum carbonitrides bysingle source routes and a study of their latticereactivity

QD Chemistry;Q Science (General)

Al shalwi, Matar ; Hargreaves, Justin

University:University of Glasgow

Department:School of Chemistry

关键词: molybdenum oxycarbonitride;   

Others  :  http://theses.gla.ac.uk/3346/1/2012alshalwimsc.pdf

来源: University of Glasgow

【 摘 要 】

Thermal decomposition of hexamethylenetetramine molybdate and ethylenediammoniummolybdate were studied using a temperature programmed reaction procedure underdifferent reaction atmospheres. The obtained materials were characterised by X-raydiffraction (XRD), surface area measurement (BET), scanning electron microscopy(SEM), elemental analysis (CHN), thermogravimetric analysis (TGA) and X-rayphotoelectron spectroscopy (XPS). The results indicated that the decomposition of bothprecursors under H2/N2 in a ratio of 3:1 or 1:3 leads to production of molybdenumcarbide, and also a mixture of molybdenum metal and molybdenum carbide is obtainedfrom the thermal decomposition of both precursors under 1:3 Ar/H2. In contrast, thedecomposition of hexamethylenetetramine molybdate under N2 or Ar leads to productionof Ɣ-Mo2N, whereas impure phases were obtained from the decomposition ofethylenediammonium molybdate where molybdenum carbide, molybdenum metal andmolybdenum oxide were obtained under an Ar atmosphere while gamma molybdenumnitride, molybdenum carbide and molybdenum oxide were obtained under a N2atmosphere. In order to characterise the reactivity of the lattice carbon and nitrogenspecies within the obtained materials various techniques have been applied. The resultshave indicated that nitrogen is much more reactive than carbon and the nature of itsreactivity is influenced by composition. The difference in reactivity observed indicatesthat molybdenum carbonitrides are not suitable candidates as reagents for which thesimultaneous loss of nitrogen and carbon from the lattice would be desirable.