In Situ Observation of the Humidity Controlled Polymorphic Phase Transformation in Glycine Microcrystals

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• 作者：Dmitry Isakov ; Daria Petukhova ; Semen Vasilev ; Alla Nuraeva ; Timur Khazamov ; Ensieh Seyedhosseini ; Pavel Zelenovskiy ; Vladimir Ya. Shur ; Andrei L. Kholkin
• 刊名：Crystal Growth & Design
• 出版年：2014
• 出版时间：August 6, 2014
• 年：2014
• 卷：14
• 期：8
• 页码：4138-4142
• 全文大小：328K
• ISSN：1528-7505

文摘

Glycine is a model crystal exhibiting three polymorphic phases and important functional properties such as piezoelectricity and ferroelectricity. We report here in situ observation of the irreversible transformation of the solution-grown glycine crystals from a 尾 phase into a 纬 phase. The slow transformation process was monitored by piezoresponse force microscopy at room temperature. The process of 尾 to 纬 conversion was entirely controlled by the variation of relative humidity in the sample chamber. The results show that the rate of phase transformation in glycine is humidity dependent with a threshold of about 25% RH. It is demonstrated that the phase boundary is highly rugged and the transformation front propagates inhomogeneously along the polar axis of the 尾 phase. The mechanism of the phase transformation is discussed.