溶胶-凝胶法制备的纳米PrOy-ZrO2固溶体的表层和体相结构

用改进的柠檬酸溶胶-凝胶法制备了纳米PrOy-ZrO2固溶体. 采用XRD, Raman和TEM等技术对纳米PrOy-ZrO2进行了表征. 结果表明, 改进的柠檬酸溶胶-凝胶法制备的PrOy-ZrO2固溶体于650 ℃焙烧后晶粒大小在5~10 nm之间; 于950 ℃焙烧(Pr>16%)后晶粒大小在20 nm左右. Pr能有效地使ZrO2稳定在四方或立方晶相. 随Pr含量的增加, PrOy-ZrO2固溶体的物相结构从单斜相逐步向四方和立方相转变. XRD和Raman得到的物相结构的差别表明, PrOy-ZrO2固溶体表层和体相结构存在不一致性, 随Pr含量增加, 体相逐步按照m→t→c的物相转变, 表层按照m→t→t"的物相转变. 表层更易生成低对称性和无序结构.

Structure on Surface and the Bulk Shell of Nanosized PrOy-ZrO2 Solid Solution Prepared by Sol-gel Method

The characterization for PrOy-ZrO2 solid solutions prepared by improved sol-gel method was performed by means of Raman, XRD, TEM and so on. It is found that the grain size of PrOy-ZrO2 solid solution calcined at 650 ℃ is 5—10 nm, and that of PrOy-ZrO2 solid solution calcined at 950 ℃[x(Pr)>16%] is about 20 nm. At a higher Pr content, phase transformation towords a higher-symmetrical phase(tetragonal or cubic) was observed. The results of phase analysis obtained by Raman spectroscopy were different from the corresponding results of XRD, which implies a structure difference between the surface and the bulk shell of the samples. With the increase of the Pr content, the m→t→c phase tramsformation occurred in the bulk area and the m→t→t" phase tramsformation occurred in the surface area. The surface region is more easily to form a low symmetry and disorder structure.