A chemical synthetic route for the preparation of fine-grained metal molybdate powders

Nanocrystalline metal molybdates [i.e., AMoO(4), where A = Ca(II). Co(II), Cu(II), Ni(II), and Zn(II)] powders have been prepared from the complete evaporation of a polymer-based metal-complex precursor solution. The metal ions are in aqueous solution through complexion with triethanolamine (TEA) and are dispersed in a polymeric reagent composed of an aqueous solution mixture of sucrose and polyvinyl alcohol (PVA), The mesoporous carbon-rich precursor powders has been obtained on complete dehydration of the precursor solution and generates the respective metal molybdate phase after complete removal of carbonaceous residue at a heat treatment temperature less than 500 degreesC. X-ray diffractometry (XRD), Differential Thermal Analysis and Thermogravimetric Analysis (TG/DTA), and Transmission Electron Microscopy (TEM) have been used to characterize the preprecursors and the heat-treated final powders. The average particle sizes as measured from X-ray line broadening and transmission electron microscopy studies are around similar to 10-30 nm. The particles having sizes of the same order with that of crystalline indicates the poor agglomeration of crystallites. (C) 2002 Elsevier Science B.V. All rights reserved.