Synthesis & investigation of novel transition metal oxides
Date of Issue2007
School of Materials Science and Engineering
Many of technologically interesting compounds are only available via high pressure oxygen synthesis at high temperature and are therefore unsuitable for large scale applications. The present project explored a simple, alternative route at near ambient temperatures and pressures to some of these coumpounds. The high temperatures required for solid state reactions are averted by mixing suitable metal salt solutions, coprecipitating at comparably low temperatures and pressures in Teflon clad autoclaves using a suitable mineralizer. The necessity of high oxygen pressures are avoided by using a cheap oxidizing agent during the co-precipitation stage. This approach enabled the synthesis of delafossites of the composition AgNi(1-x)Fe(x)O(2) and AgNi(1-x)Co(x)O(2), Ag(2)BiO(3), Ag(3)BiO(3), Ag(5)BiO(4) and Bi(2)CuO(4). In some cases it could be shown that the final product already forms during the initial co-precipitation step at room temperature. The resulting compounds have been throughly characterized by means of powder X-ray diffraction and scanning electron microscopy. Further studies of thier magnetic, electric and catalytic properties will be carried out at a later stage. The results clearly demonstrate the potential of the new approach. Therefore the project is considered to be successfully concluded.