Nanocrystalline Ce1−xYxO2−x/2 (0≤x≤0.35) Oxides via Carbonate Precipitation: Synthesis and Characterization
Nanocrystalline Ce1−xYxO2−x/2 (0≤x≤0.35) Oxides via Carbonate Precipitation: Synthesis and Characterization
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DOI：
10.1006/jssc.2002.9678
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发表时间：
2002-10
影响因子：
5.4
通讯作者：
Ji-guang Li;T. Ikegami;Yarong Wang;T. Mori
中科院分区：
文献类型：
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作者：
Ji-guang Li;T. Ikegami;Yarong Wang;T. Mori
采用硝酸根为起始盐，碳酸铵为沉淀剂的碳酸盐（co）沉淀法合成了纳米晶CeO2和Ce1−xYxO2−x/2 （x≤0.35）固溶体。通过元素分析、差热分析/热重（DTA/TG）、x射线衍射（XRD）、布鲁诺尔-埃米特-泰勒（BET）分析和高分辨率扫描电镜（HRSEM）对所得粉末进行了表征。由于在沉淀过程中直接形成碳酸盐固溶体，Ce1−xYxO2−x/2固溶体氧化物在极低的温度下（~ 300℃）煅烧2小时直接形成。由此产生的氧化物纳米粉末基本上没有团聚，这是BET和XRD分析相结合的结果。通过XRD测定YO1.5在CeO2中的溶解度在27 ~ 35 mol%之间，在此范围内，最终产物中出现了与y2o3相关的c型相。Y3+的掺杂促进了球形纳米颗粒的形成，延缓了前驱体的热分解，并显著抑制了煅烧过程中氧化物的结晶粗化。晶粒粗化的活化能从纯CeO2的68.7 kJ mol−1逐渐增大到掺35 mol% YO1.5的138.6 kJ mol−1。从固体化学的角度阐述了掺杂剂对晶体粗化的影响。
Abstract A novel carbonate (co)precipitation method, employing nitrates as the starting salts and ammonium carbonate as the precipitant, has been used to synthesize nanocrystalline CeO2 and Ce1−xYxO2−x/2 (x≤0.35) solid-solutions. The resultant powders are characterized by elemental analysis, differential thermal analysis/thermogravimetry (DTA/TG), X-ray diffractometry (XRD), Brunauer–Emmett–Teller (BET) analysis, and high-resolution scanning electron microscopy (HRSEM). Due to the direct formation of carbonate solid-solutions during precipitation, Ce1−xYxO2−x/2 solid-solution oxides are formed directly during calcination at a very low temperature of ∼300°C for 2 h. The thus-produced oxide nanopowders are essentially non-agglomerated, as revealed by BET in conjunction with XRD analysis. The solubility of YO1.5 in CeO2 is determined via XRD to be somewhere in the range from 27 to 35 mol%, from which a Y2O3-related type-C phase appears in the final product. Y3+-doping promotes the formation of spherical nanoparticles, retards thermal decomposition of the precursors, and suppresses significantly crystallite coarsening of the oxides during calcination. The activation energy for crystallite coarsening increases gradually from 68.7 kJ mol−1 for pure CeO2 to 138.6 kJ mol−1 for CeO2 doped with 35 mol% YO1.5. The dopant effects on crystallite coarsening is elaborated from the view point of solid-state chemistry.