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Size Reducing Rupture during “Growth” of LnF3 (Ln = La, Lu, Y) Nanocrystals Due to Cogeneration of Structure and Stress
Crystal Growth & Design ( IF 3.2 ) Pub Date : 2020-12-01 , DOI: 10.1021/acs.cgd.0c00835
Debadrita Bhattacharya 1 , Sayantan Sasmal 2 , Ganesh Iyer 3 , Sulay Saha 1 , Anandh Subramaniam 4 , Raj Ganesh S. Pala 1, 2 , Sri Sivakumar 1, 2, 5, 6
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Crystal growth involves an increase in the average size of crystals even during Ostwald ripening, wherein larger crystals grow at the expense of smaller crystals. In contrast, we observed particle size reduction due to rupture during the growth of polycrystalline LnF3 (Ln = Lu, Y, La) nanoparticles. We rationalize this by the feature of the growing crystal to evolve toward the most stable native crystal form via several metastable intermediate non-native amorphous or crystalline structures with a significant change in density, resulting in high misfit strain and generation of stress within the single nanoparticle. The stress promotes the propagation of already existing flaws in the crystal, leading to the rupture of nanocrystals and a subsequent decrease in crystallite size. Results from finite element elastic simulations also support the propagation of flaws leading to nanocrystal rupture if the fracture toughness of the materials is low. The ligand plays an essential role in the observation of this phase of crystal growth by retarding the growth kinetics.

中文翻译:

LnF 3(Ln = La,Lu,Y)纳米晶体“生长”过程中由于结构和应力的同时发生而导致的尺寸减小破裂

晶体生长甚至在奥斯特瓦尔德熟化过程中也涉及晶体平均尺寸的增加,其中较大的晶体以较小的晶体为代价生长。相反,我们观察到由于多晶LnF 3生长过程中的破裂而导致的粒径减小(Ln = Lu,Y,La)纳米粒子。我们通过生长中的晶体通过几个亚稳的中间非天然无定形或具有显着变化的晶体结构向最稳定的天然晶体形态发展的特征来合理化这一点,从而导致高失配应变并在单个纳米颗粒内产生应力。应力促进晶体中已经存在的缺陷的传播,从而导致纳米晶体的破裂和随后晶粒尺寸的减小。如果材料的断裂韧性低,则有限元弹性模拟的结果还支持缺陷的传播,从而导致纳米晶体破裂。配体通过阻碍生长动力学在晶体生长的这一阶段的观察中起着至关重要的作用。
更新日期:2021-01-06
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