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Influence of Crystal Growth Conditions on Formation of Macroscopic Inclusions inside Thiourea Crystals
Author(s) -
Yan Shaofeng,
Xie Chuang,
Zhang Xia,
Zhou Ling,
Hou Baohong,
Huang Jiting,
Zhou Lina,
Yin Qiuxiang
Publication year - 2018
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201702679
Subject(s) - supersaturation , crystallization , thiourea , recrystallization (geology) , ethylene glycol , crystal (programming language) , crystallography , crystal growth , inclusion (mineral) , materials science , solvent , chemistry , chemical engineering , chemical physics , mineralogy , organic chemistry , geology , paleontology , computer science , engineering , programming language
Macroscopic inclusion is an influential defect which affects purity of crystals during crystallization and remains not fully understood. In this work, we chose thiourea as the model material to investigate inclusion formation in detail. Recrystallization of thiourea were performed in deionized water, ethylene glycol, methanol, ethanol, n‐propanol, and n‐butanol under various temperature and supersaturation via cooling or evaporative modes. A series of plate‐like inclusions could form and be parallel to specific crystal faces. Polar solvent was found to be promotive to the inclusion formation due to the enhancing solute‐solvent interaction. The effect of supersaturation on inclusion formation was found to be complicated. A supersaturation window was found in which increasing supersaturation can stimulate forming inclusions. Under the lower threshold of the window, inclusion can seldom form due to low crystal growth. Beyond the upper threshold, however, inclusion formation also decreased. This supersaturation effect was explained using the “hunger center” mechanism in which the growth rate difference between the corners/edges and the center part of crystal face was considered. Moreover, a 4‐stage process during inclusion formation in batch crystallization was also discussed.