Crystallization Kinetics of Supercooled Liquid Ge-Sb Based on Ultrafast Calorimetry
Crystallization Kinetics of Supercooled Liquid Ge-Sb Based on Ultrafast Calorimetry
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DOI：
10.1021/acs.cgd.5b01151
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发表时间：
2016-01-01
影响因子：
3.8
通讯作者：
Kooi, Bart J.
中科院分区：
文献类型：
--
作者：
Chen, Bin;Momand, Jamo;Kooi, Bart J.
相变材料（PCM）的结晶动力学是相变存储技术的一个重要方面，其研究也有助于促进对结晶的理解。由于所涉及的短（纳秒）时间和小（纳米）长度尺度，PCM的结晶研究仍然具有挑战性。超快差示扫描量热法（DSC）提供了一个强有力的工具来研究结晶通过快速升温速率。在这里，我们使用这个工具来研究生长主导的Ge 7Sb 93的结晶动力学。两个模型描述的过冷液体的粘度被用来解释的数据，并随后由独立的增长率数据crosschecked。两种模型都能很好地拟合Kissinger图中的数据，但其中一种模型与独立数据存在较大差异。这些结果表明，非常小心时，需要从超快DSC测量获得晶体生长速率，因为数量级的误差可以。目前的分析表明，Ge 7Sb 93合金具有轻微的非阿氏结晶行为，对应于脆性为65，玻璃化转变温度为379 K。揭示了该合金在玻璃温度和熔化温度之间的总粘度和生长速率，以及在800 K附近的最大生长速率21 m·s（-1）。基于超快DSC数据的模型提供了对相变材料结晶动力学的解释，从而有力地支持了用于存储器应用的相变材料的设计。
: The crystallization kinetics of phase-change materials (PCMs) entails a crucial aspect of phase-change memory technology, and their study is also of interest to advance the understanding of crystallization in general. Research on crystallization of PCMs remains challenging because of the short (nanosecond) time and small (nanometer) length scales involved. Ultrafast differential scanning calorimetry (DSC) offers a powerful tool to study crystallization via ultrahigh heating rates. Here, we used this tool to study the crystallization kinetics of growth-dominant Ge7Sb93. Two models describing the viscosity of the undercooled liquid were used to interpret the data and were subsequently crosschecked by independent growth-rate data. With both models the data in Kissinger plots could be fitted well, but one of the models resulted in a large discrepancy with the independent data. These results demonstrate that great care is needed when deriving crystal-growth rates from ultrafast DSC measurements because orders of magnitude errors can be made. The present analysis showed a slightly non-Arrhenius crystallization behavior for the Ge7Sb93 alloy, corresponding to a fragility of 65 and a glass transition temperature of 379 K. The overall viscosity and growth rate of this alloy between the glass and melting temperatures have been revealed, as well as a maximum growth rate of 21 m s(-1) at similar to 800 K. Models based on ultrafast DSC data offer interpretation of crystallization kinetics of PCMs and thereby strongly support the design of PCMs for memory applications.