Multiple Nucleation and Crystal Growth of Barium Titanate

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• 作者：Hongquan Zhan ; Xianfeng Yang ; Chaomin Wang ; Jian Chen ; Yuping Wen ; Chaolun Liang ; Heather F. Greer ; Mingmei Wu ; Wuzong Zhou
• 刊名：Crystal Growth & Design
• 出版年：2012
• 出版时间：March 7, 2012
• 年：2012
• 卷：12
• 期：3
• 页码：1247-1253
• 全文大小：444K
• 年卷期：v.12,no.3(March 7, 2012)
• ISSN：1528-7505

文摘

Crystal growth of cubic BaTiO₃ in the presence of polyethylene glycol-200 (PEG-200) is investigated step by step using powder X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Titanium precursor Ti(OC₄H₉)₄ aggregates with PEG to form spherical colloidal particles at the very beginning. Multiple nucleation of BaTiO₃ takes place on the surface of these colloidal particles. The nanocrystallites then self-adjust their orientations likely under dipole鈥揹ipole interaction and/or intercrystallite interactions enhanced by surface adsorbed polymers, followed by an orientated connection and crystal extension via an Ostwald ripening process. The final BaTiO₃ crystals have a novel dodecahedral morphology. The formation mechanism is proposed to be attributed to the selective adsorption of PEG molecules on the {110} crystal planes, significantly reducing the crystal growth rate on these surfaces. A kinetic model is proposed based on the calculated crystallite sizes using the Scherrer equation. The physical meaning of the model and a significant fake reduction of the crystallite size is discussed.