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

异金属氧化物是一种很有前途的燃料电池电极材料和化学传感器材料。本文提出了一种制备二、三金属氧化物的新方法--热分解法。我们发现，具有相对较高的比表面积的异金属氧化物在低温下形成时，杂六氰基配合物作为前体。合成了LaMn（dhbaen）（OH）（NO_3）（H_2O）_4配合物，在700 ℃热分解得到钙钛矿型六方LaMnO_3。在600 ℃和700 ℃下分解的样品的粒径约为100 nm。分别为20 nm和50 nm。用<1-x><0.5><0.5>同样的方法制备了LaSmxFeO_3、NdFeCoO_3、YBa_2Cu_3O_7三金属氧化物。将LaFeO_3和SmFeO_3应用于磁控管型NO_2气敏元件，用XPS测定了其表面结构，发现用该方法制备的样品比固相反应法制备的样品具有更多的吸附位。而La_2CuO_4-CuO复合材料的电导率随H_2S气体流量的增加而显著增加。研究了该复合氧化物在H_2S气体中的反应，探讨了其反应机理。

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.