Structural study for hydrolytic condensed amorphous(Y,Zr)O_x.

以金属烷氧化合物和其他金属有机化合物为母材的溶胶-凝胶技术已经发展成为制造各种先进材料的技术，ZrO_2就是其中之一。溶胶-凝胶法得到的非晶zro_2 （a- zro_2）热分解后，除单斜zro_2 （m-ZrO_2）外，还得到亚稳四边形zro_2 （t-ZrO_2）。为了阐明这种结晶行为，我们系统地分析了a- ZrO_2的结构。采用Zr(OC_4H_9)_4与ZrOCl_2+8H_2O水溶液水解缩合法制备了两种a-ZrO_2。应用异常x射线散射技术，得到了锆周围的环境径向分布函数。锆在0.214nm的距离上被6个氧原子配位，在0.341nm的距离上被另外4个八面体包围。这种典型的局部排序与m-ZrO_2的结构相似，而与t-ZrO_2的结构相似。用同样的方法分析了稀土（Y或Er）取代的a-ZrO_2的结构。在a-ZrO_2中加入稀土元素不会改变其典型的局部结构，而稀土元素取代a-ZrO_2的结晶可以生成立方zro_2。因此，该体系的结晶行为与a-ZrO_2的结构特征无关。由于a-ZrO_2的结构不均匀性是溶胶-凝胶法制备材料的特征性质之一，因此研究a-ZrO_2的结构不均匀性是非常必要的。

The sol-gel technique using metal alkoxides and other metal organic compounds as master materials has been developed for making various advanced materials and ZrO_2 is known to be included in this category. Thermal decomposition of amorphous-ZrO_2(a-ZrO_2) obtained by this sol-gel method produces a metastable tetragonal-ZrO_2(t-ZrO_2) in addition to monoclinic-ZrO_2(m-ZrO_2). In order to clarify this crystallization behavior, we analyzed the structure of a- ZrO_2 systematically. Two kinds of a-ZrO_2 were prepared by the hydrolytic condensation of Zr(OC_4H_9)_4 and the aqueous solution of ZrOCl_2+8H_2O. The anomalous X-ray scattering technique has been applied to obtain the environmental radial distribution function around a zirconium. Zirconium is quantitatively confirmed to be coordinated by six oxygens at a distance of 0.214nm and this Zr-octahedron is surrounded by other four octahedra at a distance of 0.341nm. This typical local ordering is suggested to be similar to that in the structure of m-ZrO_2 rather than that of t-ZrO_2. The structure of REE(Y or Er) substituted a-ZrO_2 have been analyzed in similar way. The typical local structure was not changed by the addition of REE elements to the a-ZrO_2, although cubic-ZrO_2 is produced by the crystallization of REE substituted a-ZrO_2. Therefore, it is rather suggested that the crystallization behavior is independent of the structural feature of a-ZrO_2 in this system. The research by using X-ray small-angle diffraction is strongly required for discussing the structural inhomogeneity in a-ZrO_2, which is one of the characteristic natures of the materials produced by sol-gel technique.