SOL-GEL SYNTHESIS OF TERNARY METAL-OXIDES .1. SYNTHESIS AND CHARACTERIZATION OF MAL2O4 (M = MG, NI, CO, CU, FE, ZN, MN, CD, CA, HG, SR, AND BA) AND PB2AL2O5

Several ternary metal oxides having the formula MAl2O4 where M = Mg, Ni, Co, Cu, Fe, Zn, Mn, Cd, Cu, Hg, Sr, and Ba and the compound Pb2Al2O5 have been synthesized with sol-gel methods and compared to materials produced by traditional high-temperature solid-state procedures. These transparent sol-gel materials are crystalline as shown by powder X-ray diffraction methods. The size and charge of M ions and their corresponding resultant structures are found to be related to crystal field and octahedral stabilization energies. Particle sizes range from 20 to 200 mum as determined by scanning electron microscopy experiments. Thermal stability of the NiAl2O4 material has been studied by differential scanning calorimetry methods. Small metal (M) ions form different structures such as the cubic Pb2Al2O5 phase, the hexagonal phase of BaAl2O4, the monoclinic phase of CaAl2O4, and the hexagonal CdAl2O4 and HgAl12O13 phases.