【摘要】 用Al(NO3)3和ZrO(NO3)2混合溶液,加氨水共沉淀制备了一系列Al2O3含量由低到高的ZrO2-Al2O3复合氧化物,用XRD、XPS、BET等实验手段对其进行了表征.结果表明,随着一种组分含量由低到高,其主要存在形式按形成固溶体-表面单层分散-析出单独晶相的规律变化,而一种组分的加入均使另一种组分的XRD衍射峰明显宽化,晶粒变细;复合氧化物的比表面明显大于两种组分纯样品比表面的简单加和.实验表明体系中两种组分存在相互表面单层分散,即在一定的相对含量范围内,该体系的任一组分的微晶固溶体都既接受另一组分在其表面上的单层分散,同时也在另一组分的微晶固溶体表面上单层分散.相互单层分散和固溶体的生成都可能使高温焙烧时微晶的增大受到抑制,从而维持了样品的高比表面.更多还原

【Abstract】 A series of ZrO2 Al2O3 composites with various compositions were synthesized through heat decomposition of metal hydroxides, which were prepared by co precipitation with NH4OH from aqueous solution of nitrates. The samples were characterized by XRD, XPS and BET measurements. It was found that with content increasing, one component tended to dissolve into the bulk phase of the other to form solid solution first. After the dissolution reached saturation, a component started to disperse onto the surface of the crystallite of the solid solution of the other component. The formation of the separate crystalline phase of one component was observed only when its content was higher than a certain percentage. The XRD peaks of the composites were significantly broadened, and the BET specific surface areas of the composites were larger than those of the pure oxides, which suggested that the crystallites became smaller. The experimental results showed the existence of mutual dispersion of both components in this system. It means that in a certain content range, the the crystallite of the solid solution of each component can accept the dispersion of the other component. The phenomenon of mutual dispersion and formation of solid solution would make the crystallites smaller, and lead to higher surface area, since the process could hinder the interface diffusion and crystallite sintering.更多还原