Abstract
Defects in cerium oxide, especially oxygen vacancies, play an essential role in its versatile applications and are efficiently preserved at ambient conditions in a nonequilibrium process. Herein, defective CeO2-x with heterogeneous structure was synthesized by high-energy laser melting, where a large amount of oxygen vacancies and Ce3+ could be introduced, leading to improved visible light absorption, narrowed bandgap and room temperature ferromagnetism. Moreover, this laser melted CeO2-x exhibits significantly enhanced low-temperature oxidation behaviors than the counterpart prepared by normal hydrogen-reduction. This unique redox performance could be attributed to the intragranular diffusion at the boundaries of assembled nanocrystallites. This method paves a new way for introducing unique multi-functions in oxide ceramics.
摘要
本文采用高能激光熔化技术制备出具有非平衡非均匀结构的CeO2−x纳米晶. 大量氧空位和Ce3+的使可见光吸收率提升, 禁带宽度变窄及室温铁磁性增强. 此外, 与通常氢还原的样品比较, 这种激光熔融得到的CeO2−x呈现出增强的低温氧化能力. 这种独特的氧化还原行为可归因于通过聚并的纳米晶的晶界扩散. 这一方法为多功能氧化物陶瓷的制备提供了一条新的途径.
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Acknowledgements
We thank Dr. Jiang H (Center for Testing & Analyzing of Materials, School of Materials Science and Engineering, Tsinghua University) for the help in XPS data processing and analyzing, and Prof. Chen C and Prof. Thommy Ekstrom for valuable advices and revising the manuscript. This work was supported by the National Natural Science Foundation of China (51272124 and U1605243).
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Lu Song is currently a PhD candidate in the School of Materials Science and Engineering, Tsinghua University. His current study focuses on the effects of laser melting on the microstructure and functional performance of oxide ceramics.
Zhijian Shen is a joint professor in Tsinghua University and Stockholm University. He has long been engaged in the research of material chemistry and manufacturing engineering, and has conducted systematic research work in the fields of advanced ceramic materials, biomaterials and nanomaterials. His current research focuses on increasing the complexity of material structures through additive manufacturing or biomimetic design to improve material properties and multifunctional composites.
Jing Ma is an assistant professor in the School of Materials Science and Engineering, Tsinghua University. Her researches include high performance multiferroic composites and device prototypes, oxide heterostructures and novel microstructure and functional properties of oxide ceramics.
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Song, L., Ma, J., Zhang, Q. et al. Unique redox properties in defective CeO2-x nanocrystallines synthesized by laser melting. Sci. China Mater. 61, 1078–1084 (2018). https://doi.org/10.1007/s40843-017-9226-5
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DOI: https://doi.org/10.1007/s40843-017-9226-5