Letter. Characterization of supercooled liquid Ge2Sb2Te5 and its crystallization by ultrafast-heating calorimetry
Orava, J., Greer, A.L., Gholipour, B., Hewak, D.W. and Smith, C.E. (2012) Letter. Characterization of supercooled liquid Ge2Sb2Te5 and its crystallization by ultrafast-heating calorimetry. Nature Materials, 11, (4), 279-283. (doi:10.1038/NMAT3275).
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Differential scanning calorimetry (DSC) is widely used to study the stability of amorphous solids, characterizing the kinetics of crystallization close to the glass-transition temperature Tg.We apply ultrafast DSC to the phase-change material Ge2Sb2Te5 (GST) and show that if the range of heating rates is extended to more than 10^4 K s^-1, the analysis can cover a wider temperature range, up to the point where the crystal growth rate approaches its maximum. The growth rates that can be characterized are some four orders of magnitude higher than in conventional DSC, reaching values relevant for the application of GST as a data-storage medium. The kinetic coefficient for crystal growth has a strongly non-Arrhenius temperature dependence, revealing that supercooled liquid GST has a high fragility. Near Tg there is evidence for decoupling of the crystal-growth kinetics from viscous flow, matching the behaviour for a fragile liquid suggested by studies on oxide and organic systems.
|Digital Object Identifier (DOI):||doi:10.1038/NMAT3275|
|Subjects:||Q Science > QC Physics
T Technology > TK Electrical engineering. Electronics Nuclear engineering
|Divisions:||Faculty of Physical Sciences and Engineering > Optoelectronics Research Centre
|Date Deposited:||28 Mar 2012 10:34|
|Last Modified:||14 Apr 2014 11:38|
NANOSTRUCTURED PHOTONIC METAMATERIALS
Funded by: EPSRC (EP/G060363/1)
Led by: Nikolay Zheludev
1 January 2010 to 31 December 2015
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