高等学校化学学报

高等学校化学学报 ›› 2001, Vol. 22 ›› Issue (4): 524.

• 研究论文 • 上一篇    下一篇

单相Ce0.5Zr0.5O2立方固溶体的高压高温合成

许大鹏1,2, 王权泳1,2, 张弓木1,2, 李莉萍1,2, 苏文辉1,2,3,4   

  1. 1. 吉林大学物理系;
    2. 吉林大学无机合成与制备化学教育部重点实验室, 长春 130023;
    3. 中国科学院国际材料物理中心, 沈阳 110015;
    4. 中国高等科学技术中心(世界实验室)凝聚态和辐射物理分中心, 北京 100080
  • 收稿日期:2000-04-04 出版日期:2001-04-24 发布日期:2001-04-24
  • 通讯作者: 许大鹏(1960年出生),男,硕士,教授,从事凝聚态物理研究.
  • 基金资助:

    国家自然科学基金(批准号:19874023)资助

Synthesis of Single phase Cubic Ce0.5Zr0.5O2 Solid Solution under High Pressure and High Temperature

XU Da-Peng1,2, WANG Quan-Yong1,2, ZHANG Gong-Mu1,2, LI Li-Ping1,2, SU Wen-Hui1,2,3,4   

  1. 1. Department of Physics;
    2. Key Lab of Inorganic Syn thesisand Prepa rative Chemistry, Jilin University, Changchun 130023, China;
    3. International Centerf or Materials Physics, Academia Sinica, Shenyang, 110015, China;
    4. Centerf or Condensed Matterand Radiation Physics, CCAST(World Lab.), Beijing 100080, China
  • Received:2000-04-04 Online:2001-04-24 Published:2001-04-24

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摘要： 以化学沉淀法制备的CeO2和ZrO2纳米微粒为前驱体,首次在高压高温(3.1GPa,1073K)下合成了单相Ce0.5Zr0.5O2面心立方固溶体.使用X射线衍射、TG-DTA、XPS、Raman、电子自旋共振谱和交流阻抗谱等对样品的结构、Ce离子的价态和导电性进行了表征.实验结果表明,纳米CeO2-50%ZrO2混合物在高压(0.9GPa以上)高温(1073K以上)条件下可以发生固态反应,高压下固溶温度明显降低.Ce0.5Zr0.5O2面心立方固溶体在773K以下是热稳定的,不发生结构转变,固溶体中Ce离子完全以Ce4+形式存在,773K退火也不引起Ce4+向Ce3+转变,晶格中氧缺位非常少.Ce0.5Zr0.5O2面心立方固溶体是离子导电,823K时电导率σ=1.2×10-5S/cm,与纯CeO2在同温度下的电导率同数量级;1123K时σ=2.1×10-3S/cm,小于掺入稀土或碱土氧化物的氧化锆和氧化铈基电解质的电导率.在高温区和低温区ln(σT)与1/T的关系满足斜率不同的二条直线,低温活化能小于高温活化能.固溶体的显微硬度(50g载荷)为572HV.

关键词: CeO2, ZrO2, 纳米晶, 高压高温, 固溶体

Abstract: Using nanoparticles of CeO2 and ZrO2 prepared by chemical precipition method as the starting materials, the single phase cubic Ce0.5 Zr0.5 O2 solid solution has been synthesized under high pressure and high temperature for the first time. The structural characteristics and valence state of the single phase cubic Ce0.5 Zr0.5 O2 solid solution were investigated by XRD, TG-DTA, Raman, XPSand EPRmeasurements. The XRDresults showed that the nanocrystalline mixtures of CeO2-50% ZrO2 can form a cubic Ce1-x Zrx O2 solid solution above 1.67 GPa and above 1073 K, but the product is in a mixture state. The single phase cubic Ce0.5 Zr0.5 O2 solid solution can be obtained only under the certain conditions of 3.1 GPa at 1073 K. The high pressure promotes the process of the solid state reaction and the temperature of forming CeO2 ZrO2 solid solution decreases under high pressure. The DTAcurve of the single phase cubic Ce0.5 Zr0.5 O2 solid solution showed a broad exothermic peak between 403 Kand 742 K. But the XRD pattern and Raman spectra displayed that the structure of the solid solution had not been changed before and after annealing at 773 Kfor 1 h. It revealed that the cubic Ce0.5 Zr0.5 O2 solid solution was stable in structure below 773 K. The EPRspectra recorded at room temperature gave an evidence of the presence of Ce 3+ and O2- in CeO2 nanoparticles. However, the signals of Ce 3+ and O2- have not been detected in Ce0.5 Zr0.5 O2 solid solution. An unknown signal( g=1.990) has been observed in cubic Ce0.5-Zr0.5 O2 solid solution which has not been changed after annealing at 773 K for 1 h, exhibiting that there exists no Ce 3+ in cubic Ce0.5 Zr0.5 O2 solid solution and the Ce 4+ has not been reduced into Ce 3+ after annealing. The hyperfine structure in Zr3d XPS spectrum has been observed for the Ce0.5 Zr0.5 O2 solid solution. It shows that there may exist some Zr ions with a low valence state. The ionic conductivity measured by impedance spectroscopy showed that the cubic Ce0.5 Zr0.5 O2 solid solution exhibits only the bulk conductivity. The bulk conductivity( σ=1.2× 10-5 S/cm at 823 K, σ=2.1×10-3 S/cm at 1123 K) is the same as that of CeO2, but smaller than that of Y2O3-stabilized ZrO2. Amarked curvature at T=823 Khas been observed in the Arrhenius plot of the bulk conductivity. The activation energy below 823 Kis lower than that above 823 K, and the reason has been discussed.

Key words: Cerium oxide, Zirconium oxide, Nanocrystalline, High-pressure and high-temperature, Solid solution

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