Málek Jiří, Podzemná Veronika, Shánělová Jana
Department of Physical Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentská 573, Pardubice 532 10, Czech Republic.
J Phys Chem B. 2021 Jul 15;125(27):7515-7526. doi: 10.1021/acs.jpcb.1c03243. Epub 2021 Jul 2.
The crystal growth kinetics and morphology in germanium disulfide bulk glass and glass surface is described. The structural relaxation taking place below the glass transition is slow and the corresponding volumetric change is negligible. Therefore, it does not affect substantially the crystal growth process. The crystal growth rate of low temperature β-GeS and high temperature α-GeS polymorphs in the bulk glass is comparable, being slightly decoupled from the shear viscosity below the glass transition. The crystal growth rate of β-GeS in an amorphous thin film of the same composition is several orders of magnitude faster than that at the surface of bulk glass. This fast surface crystal growth is strongly decoupled from viscosity. Such behavior resembles the glass-to-crystal fast growth mode observed by several authors in some organic molecular glasses. Taking into account previously reported viscosity and heat capacity data, the crystal growth kinetics of both polymorphs can be quantitatively described by the 2D surface growth model for low and high supercooling. The nonisothermal differential scanning calorimetry experiments are analyzed, providing evidence of a complex nature of the overall crystallization process with apparent activation energy comparable to that obtained from isothermal microscopy measurement of crystal growth in the same temperature range.
描述了二硫化锗块状玻璃和玻璃表面的晶体生长动力学及形态。在玻璃转变温度以下发生的结构弛豫缓慢，相应的体积变化可忽略不计。因此，它对晶体生长过程影响不大。块状玻璃中低温β-GeS和高温α-GeS多晶型物的晶体生长速率相当，在玻璃转变温度以下与剪切粘度略有解耦。相同组成的非晶薄膜中β-GeS的晶体生长速率比块状玻璃表面的生长速率快几个数量级。这种快速的表面晶体生长与粘度强烈解耦。这种行为类似于几位作者在一些有机分子玻璃中观察到的玻璃到晶体的快速生长模式。考虑到先前报道的粘度和热容数据，两种多晶型物的晶体生长动力学可以通过低过冷度和高过冷度的二维表面生长模型进行定量描述。对非等温差示扫描量热法实验进行了分析，提供了整体结晶过程具有复杂性质的证据，其表观活化能与在相同温度范围内通过等温显微镜测量晶体生长获得的活化能相当。
