CHARACTERIZATION OF THE THERMAL GENESIS COURSE OF ZINC-OXIDE FROM ZINC ACETOACETONATE DIHYDRATE

The thermal decomposition course of Zn(acac)2, Zn(C5H7O2)2.2H2O, was characterised to the onset of formation of ZnO. The techniques employed were thermogravimetry (TG), differential thermal analysis (DTA), infrared spectroscopy (IR) and X-ray diffractometry (XRD). The results obtained showed that Zn(acac)2 dehydrates in two consecutive steps at 87 and 110-degrees-C, melts at 143-degrees-C and, then, releases C3H4 to yield Zn(CH3COO)2 at 209-degrees-C. Subsequently, the acetate released CH3COCH3 and CO2 to give (ZnCO3)x.(ZnO)y at 240-degrees-C, which on further heating to 665-degrees-C, decomposed giving ZnO. IR spectroscopy of the gaseous products revealed that a profound chemical reactivity at the gas/solid interfaces was generated throughout the decomposition course. As a result, CH3COCH3 was involved in bimolecular interactions over freshly genesised ZnO surfaces, producing CH4 and (CH3)2C = CH2 (isobutene) in the gas phase and acetate surface species.