纳米晶固溶体Ce_(0.8)Nd_(0.2)O_(2-δ)的合成与表征

Synthesis and Characterization of Nanocrystalline Ce_ (0.8) Nd_(0.2) O_(2-δ) Solid Solution

利用溶胶 -凝胶法合成纳米晶固溶体 Ce0 .8Nd0 .2 O2 -δ.XRD测试表明 ,胶体经 2 0 0℃烧结处理就可以得到晶粒尺寸为 7.2 nm的纳米晶 ,随烧结温度的升高 ,晶粒尺寸增大 .EPR测试给出固溶体 Ce0 .8Nd0 .2 O2 -δ存在少量的 Ce3 +离子 .在纳米晶固溶体 Ce0 .8Nd0 .2 O2 -δ的 Raman光谱上观察到两个峰 ,低频的强峰为特征F2 g振动谱带 ,高频谱带的出现与样品中存在氧缺位有关 .固溶体晶粒尺寸的减小不但使 F2 g振动谱带红移 ,而且谱带明显宽化 .复阻抗谱的测量表明 ,固溶体 Ce0 .8Nd0 .2 O2 -δ具有氧离子导电特性 .4 0 0和 50 0℃时的电导率分别为 4 .55× 1 0 -4 和 2 .65× 1 0 -3 S· cm-1,活化能为 0 .82 e

The solid solution Ce 0.8 Nd 0.2 O 2- δ was prepared by sol gel method. The XRD measurements showed that the product obtained by sintering the fresh gel at 200 ℃ crystallized in a single fluorite structure and its grain size was calculated to be ca . 7.2 nm by Scherrer formula. With the increase of sintering temperature, the grain size of solution increases. A few of Ce 3+ ions were detected by EPR measurement. The first order Raman spectra of the solid solutions exhibited two peaks. The strong band F 2g mode at a lower frequency is assigned to symmetric breathing mode of the oxygen atoms around cerium ions, while the weak band at ca . 570 cm -1 is related with the existence of oxygen vacancies. With the grain decrease, the F 2g mode shifts to the lower frequency, while the half height width becomes broaden. The ionic conductivity for the solid solution Ce 0.8 Nd 0.2 O 2- δ at 500 ℃( σ 500 ℃ ) is 2.65×10 -3 S·cm -1 , and the activation energy is 0.82 eV.