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首页> 外文期刊>Crystal growth & design >Hydrothermal synthesis of CeO _2 nanocrystals: Ostwald ripening or oriented attachment?
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Hydrothermal synthesis of CeO _2 nanocrystals: Ostwald ripening or oriented attachment?

机译：CeO _2纳米晶体的水热合成：奥斯特瓦尔德熟化或定向附着？

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The growth mechanism of CeO _2 nanocrystals prepared by the hydrothermal method has been studied in this article. The synthesis of CeO _2 nanocrystals follows two stages, the initial nucleation of CeO _2 nuclei and the subsequent ripening of nuclei in the hydrothermal process. The nucleation involves the precipitation of Ce ~(3+) cations by OH ~- ions to form Ce(OH) _3 nanoparticles and the transition from Ce(OH) _3 to 2-3 nm CeO _2 nuclei through an oxidation and rapid dehydration process. In the hydrothermal process, the oriented attachment of nuclei through a lattice matched surface and subsequent Ostwald ripening results in the growth of CeO _2 nanocrystals. The dominant mechanism for the ripening of nuclei in hydrothermal reactions is the oriented attachment. The addition of polyvinylpyrrolidone surfactant and adjustment of solution acidity can promote the dispersion of the nuclei and enhance the effective collision among them in the hydrothermal stage, resulting in the oriented aggregation of particles and further growth into larger CeO _2 nanocrystals (～15 nm). Because of the low solubility of CeO _2 crystals in water, the Ostwald ripening process (dissolution/reprecipitation) only plays the second important role in the hydrothermal reactions, which converts the assembly clusters into nanocrystals with/without well-defined edges or contributes to the further growth of nuclei from 2-3 nm to 3-5 nm.
机译：本文研究了水热法制备的CeO _2纳米晶的生长机理。 CeO _2纳米晶体的合成经历两个阶段，即CeO _2核的初始成核和随后在水热过程中核的成熟。成核过程涉及通过OH〜-离子沉淀Ce〜（3+）阳离子以形成Ce（OH）_3纳米颗粒，以及通过氧化和快速脱水过程将Ce（OH）_3转变为2-3 nm CeO _2核。 。在水热过程中，原子核通过晶格匹配表面定向附着并随后进行奥斯特瓦尔德成熟，导致CeO _2纳米晶体的生长。水热反应中原子核成熟的主要机制是定向附着。聚乙烯吡咯烷酮表面活性剂的添加和溶液酸度的调节可促进水热阶段原子核的分散并增强它们之间的有效碰撞，从而导致粒子定向聚集并进一步生长成较大的CeO _2纳米晶体（〜15 nm）。由于CeO _2晶体在水中的溶解度低，奥斯特瓦尔德熟化过程（溶解/再沉淀）仅在水热反应中扮演第二重要角色，它将组装簇转变为具有/不具有明确边界的纳米晶体，或者有助于原子核从2-3 nm进一步生长到3-5 nm。

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