2026-09-22T23:55:34Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/82789 2023-07-11 col_2142_5131 col_2142_13836 com_2142_5130 com_2142_13835 com_2142_234

Abelson, John R. Lee, Bong-Sub 2015-09-25T20:53:01Z 2015-09-25T20:53:01Z 10000-01-01 2006 2006 One long standing puzzle was that, for a fixed composition, there may be different amorphous states that have greatly different crystallization kinetics. We provided clear evidence for the existence of nanoscale structural order in all amorphous states of Ge2Sb2Te5 and AgInSbTe, using Fluctuation electron microscopy (FEM) carried out in the transmission electron microscope. The nanoscale order is higher in the thermally annealed amorphous states than in the as-deposited (sputtered) state. Higher nanoscale order corresponds to more or larger ordered regions; then the structure has a greater probability to have supercritical nuclei that later grow into crystalline grains. The crystallization speeds of the annealed states are indeed higher than that of the as-deposited states. The greatly different effects of annealing on Ge2Sb2Te5 and AgInSbTe were explained by the difference in the nucleation rates. We also demonstrated that melt-quenched amorphous Ge2Sb2Te5 has clearly indexable crystalline particles of several nanometers, in addition to the amorphous matrix with high nanoscale order; the nanoparticles can act as supercritical nuclei that result in an order of magnitude faster crystallization. Made available in DSpace on 2015-09-25T20:53:01Z (GMT). No. of bitstreams: 2 license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5) 3242913.pdf: 3289354 bytes, checksum: e766153c1e7c3aeb02ff46f2e75b7bc8 (MD5) Previous issue date: 2006 Embargo set by: Seth Robbins for item 84070 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs U of I Only 122 p. Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006. http://hdl.handle.net/2142/82789 (MiAaPQ)AAI3242913 eng Engineering, Materials Science Optical and Electronic Properties, Nanoscale Structural Order, and Transformation Kinetics of Phase Change Materials text Materials Science and Engineering Materials Science and Engineering University of Illinois at Urbana-Champaign Dissertation Ph.D.