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首页> 外文期刊>Physical chemistry chemical physics: PCCP >Electronic structure study of Ce_(1-x)A_xO2 (A = Zr & Hf) nanoparticles: NEXAFS and EXAFS investigations
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Electronic structure study of Ce_(1-x)A_xO2 (A = Zr & Hf) nanoparticles: NEXAFS and EXAFS investigations

机译：CE_（1-X）A_XO2（A = ZR＆HF）纳米粒子的电子结构研究：NEXAFS和EXAFS调查

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摘要

Single phase nanoparticles (NPs) of CeO2, Ce_(0.5)Zr_(0.5)O2, Ce_(0.5)Hf_(0.5)O2 and Ce_(0.5)Hf_(0.25)Zr_(0.25)O2 were successfully synthesized by co-precipitation method at constant pH and temperature. The X-ray diffraction results revealed that the additive atoms did not segregate to form secondary phases but led to grain size variation in the NPs. The 10 Dq values in the near edge X-ray absorption fine structure (NEXAFS) spectra at the O K-edge did not vary in the same way as the average grain size was changed for the doped CeO2 NPs. The deconvolution of Ce M5-edge and detailed analysis of O K pre-edge peak have shown the higher Ce~(+3)/(Ce~(+3) + Ce~(+4)} ratio in the Zr-and Hf-doped samples. The local atomic structure around the Ce, Zr and Hf atoms was investigated using extended X-ray absorption fine structure (EXAFS) spectroscopy at Ce K-edge, Zr K-edge and Hf L3-edge, respectively, and the EXAFS data were fitted with the theoretical calculations. The 4f occupancy, Ce~(+3)/(Ce~(+3) + Ce~(+4)) ratio of Ce ions, coordination number of Ce and Ce-Ce/Ce-O bond distances were sensitive to the additive atoms but not explicitly changed according to the grain size variation in the NPs.
机译：CeO2的单相纳米颗粒（NPS），Ce_（0.5）Zr_（0.5）O 2，Ce_（0.5）HF_（0.5）O 2和Ce_（0.5）HF_（0.25）Zr_（0.25）Zr_（0.25）O2通过共沉淀法合成在恒定的pH和温度下。 X射线衍射结果表明，添加剂原子没有隔离以形成二次相，但导致NPS的晶粒尺寸变化。邻近边缘X射线吸收精细结构（NEXAF）的10 dq值在O k边缘处的光谱与掺杂CEO2 NPS改变的平均晶粒尺寸相同的方式没有变化。 Ce m5边缘的去卷积和OK预先峰的详细分析表明Zr-and hf-中较高的Ce〜（+3）/（Ce〜（+3）+ Ce〜（+4）}比掺杂样品。使用Ce k-Edge，Zr K-Edge和HF L3边缘的延长的X射线吸收细结构（Exafs）光谱，以及外爆来研究Ce，Zr和HF原子周围的局部原子结构数据具有理论计算。4F占用，Ce〜（+3）/（Ce〜（+ 3）+ Ce〜（+4））的Ce离子，Ce和Ce-Ce / Ce的协调数量 - o键距离对添加剂原子敏感但根据NPS的晶粒尺寸变化而没有明确改变。

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