均相沉淀法制备Ce_(0.8)Y_(0.2)O_(1.9)氧化物固溶体的研究

Study of Preparing Ce_(0.8)Y_(0.2)O_(1.9) Solid Solution by Homogenous Precipitation

采用草酸二乙酯、Ce（NO3）3.6H2O、Y（NO3）3.6H2O为出发原料,以尿素为pH调节剂达到了Ce^3＋、Y^3＋的均相共沉淀。重点考察尿素对溶液pH以及形成的粒子形貌的影响。实验表明：体系的pH随温度的升高由于草酸二乙酯、金属离子的水解作用加强而下降。尿素的水解一方面促进了草酸二乙酯的水解,另一方面提高了沉淀形成的环境pH。在尿素添加量x=0～35.5（x：尿素与草酸二乙酯的摩尔分数）的情况下,体系升温前及发生沉淀时的pH均随x的增大而上升。经扫描电子显微镜观察,发现生成的草酸盐及相应的氧化物颗粒大小均随x的增大而减小,由x=0时约10μm下降到x=35.5时约0.5μm。沉淀物经500℃,1 h热处理后,得到的氧化物经X-射线衍射仪的结晶相分析表明为Y固溶CeO2,其结晶粒径为9.2 nm。

Oxalate solid solution was obtained in a mixed aqueous solution system of diethyl oxalate, cerium nitrate and yttrium nitrate with urea as pH adjuster by homogenous precipitation. It was found that the pH of the mixed solution system decreased with increasing temperature because of increased hydrolysis of the diethyl oxalate and Ce^3＋ , Y^3＋ ion. The hydrolysis of the urea not only promoted the hydrolysis of the diethyl oxalate but also increased the pH of the mixed solution. Both the pH values before heating and at the precipitation increased with increasing x （x： mole ratio of urea to diethyl oxalate ） when the x is in the range of 0-35. 5. The SEM observation indicated that the precipitate and its corresponding average oxide particle size decreased from about 10μm to 0.5μm with x increasing from 0 to 35.5. The XRD analysis of the oxide from the precipitate by heating at 500 ℃ for lh indicated that the oxide was Y doped CeO2 with crystal size 9.2 nm.