Preparation, characterizations, and applications for heterometallic-oxides prepared by thermal decomposition of new heteronulear complexes

杂金属烯丙基氧化物是一种很有前途的燃料电池电极和化学传感器材料。我们提出了异核配合物热分解作为制备二、三金属氧化物的一种新方法。我们发现，以异核六氰基络合物为前驱体，在较低的温度下形成了具有较高比表面积的异金属氧化物。合成了LaMN(Dhbaen)(OH)(NO3)(H2O)4异核配合物，在700℃下热分解得到了钙钛矿型六方相LaMnO3。在600℃和700℃下分解的样品的粒径分别约为20 nm和50 nm。此外，用同样的方法制备了均匀的La_&lt；1-x&gt；Sm_xFeO_3，NdFe_&lt；0.5&gt；Co_&lt；0.5&gt；O_3，YBa2Cu3O_7三金属氧化物。将LaFeO_3和SmFeO_3应用于半导体型NO_2气敏元件，并用X射线光电子能谱(XPS)对其表面结构进行了测定。而10ppm的H_2S气体对La_2CuO_4-CuO复合体系的电导率变化影响较大。研究了复合氧化物在H_2S气体中的反应，以确定其反应机理。

Heterometalllic oxides are one of the promising material as electrodes of fuel cells and chemical sensors. We have been proposed the thermal decomposition of heteronuclear complexes as a new method for the preparation of di- or tri-metallic oxides. We found that heterometallic oxides with relatively high specific surface area were formed at low temperatures when heteronuclear hexacyano-complexes were used as precursors. The heteronuclear LaMn(dhbaen)(OH)(NO_3)(H_2O)_4 complex was synthesized and perovskite-type hexagonal LaMnO_3 was obtained by its thermal decomposition at 700 ℃. Particle size of the samples decomposed at 600 ℃ and 700 ℃ is ca. 20 nm and 50 nm, respectively. Furthermore, homogenious La_<1-x>Sm_xFeO_3, NdFe_<0.5>Co_<0.5>O_3, YBa_2Cu_3O_7 tri-metallic oxides were prepared using same method. LaFeO_3 and SmFeO_3 were applied for semiconductor-type NO_2 gas sensors and determined its surface structure using XPS.The number of adsorption sites for the sample prepared by this method was larger than that by solid reaction method. On the other hand, the change of the electrical conductivity for composite La_2CuO_4-CuO was strongly changed by the 10 ppm H_2S gas flow. The reaction of the composite oxide in H_2S gas was investigated to determine its mechanism.