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Title: Novel Polymorphic Phase of BaCu 2 As 2 : Impact of Flux for New Phase Formation in Crystal Growth
Award ID(s):
1921581 1922076 1921847 1921798
NSF-PAR ID:
10195547
Author(s) / Creator(s):
; ; ; ; ; ; ; ;
Date Published:
Journal Name:
Crystal Growth & Design
Volume:
20
Issue:
9
ISSN:
1528-7483
Page Range / eLocation ID:
5922 to 5930
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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  1. Abstract

    Controlling crystallization kinetics is key to overcome the temperature–time dilemma in phase change materials employed for data storage. While the amorphous phase must be preserved for more than 10 years at slightly above room temperature to ensure data integrity, it has to crystallize on a timescale of several nanoseconds following a moderate temperature increase to near 2/3Tmto compete with other memory devices such as dynamic random access memory (DRAM). Here, a calorimetric demonstration that this striking variation in kinetics involves crystallization occurring either from the glassy or from the undercooled liquid state is provided. Measurements of crystallization kinetics of Ge2Sb2Te5with heating rates spanning over six orders of magnitude reveal a fourfold decrease in Kissinger activation energy for crystallization upon the glass transition. This enables rapid crystallization above the glass transition temperatureTg. Moreover, highly unusual for glass‐forming systems, crystallization at conventional heating rates is observed more than 50 °C belowTg, where the atomic mobility should be vanishingly small.

     
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