Abstract
The thermal decomposition of ammonium molybdate-basic magnesium carbonate and the solid-solid interactions of the resulting solids were studied for pure and lithium nitrate doped samples. The techniques employed were TG, DTG, DTA and XRD. The composition of pure calcined solids was 0.5 MoO3-MgO and the dopant concentrations were 1, 2 and 4 mol% Li2O. Pure mixed solids were prepared by wet impregnation method using a known mass of finely powdered basic magnesium carbonate with a calculated amount of ammonium molybdate dissolved in the least amount of distilled water. The three doped samples were prepared by treating basic magnesium carbonate with different proportions of lithium nitrate dissolved in the least amount of distilled water prior to impregnation with ammonium molybdate. The results revealed that lithium doping of the reacting solids enhanced their decomposition and stimulated their solid-solid interaction taking place at less than or equal to500degreesC yielding MgMoO4 to an extent proportional to its amount added. Opposite effect was observed when the doped solids were heated at >600degreesC. These results were discussed in terms of an effective increase in the mobility of reacting molybdenum and magnesium species.