Preparation of nanocrystalline metal oxides and intermetallic phases by controlled thermolysis of organometallic coordination polymers

摘要

Organometallic coordination polymers of the super-Prussian blue type ((Me_3Sn)_nM(CN)_6) (Me = CH_3; n = 3, 4; M = Fe, Co, Ru) were subjected to thermolysis in different atmospheres (air, argon, hydrogenitrogen). In air, oxides were found: Fe_2O_31SnO_2 (crystalline and nanocrystalline), Co_2SnO_4 and RuO_2. In argon and in hydrogen, the intermetallic phases FeSn_2, CoSn_2, Ru_3Sn_7 and Fe_3SnC were obtained. A detailed mechanistic study was carried out using thermogravimetry (TG), X-ray diffraction (XRD), X-ray absorption spectroscopy (EXAES) at Fe, Co, Ru and Sn K-edges, infrared spectroscopy (IR) and elemental analysis. Below 250 deg C, Me_3SnCN and (CN)_2 are released, whereas above 250 deg C oxidation or pyrolysis leads to the corresponding oxides or intermetallic phases. Polymeric cyanides containing at least two metals have turned out to be suitable precursors to prepare well-defined oxides and intermetallic phases at comparatively low temperature.