1996 Fiscal Year Final Research Report Summary
Cooperative Phenomena on Grass Transition of Amorphous Semiconductors -Hierarchical Energy Distribution and Fractal Structure-
| Project/Area Number |
07640502
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
物性一般(含基礎論)
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| Research Institution | University of Tsukuba |
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Principal Investigator |
MATSUISHI Kiyoto University of Tsukuba Institute of Applied Physics Assistant Professor, 物理工学系, 講師 (10202318)
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| Co-Investigator(Kenkyū-buntansha) |
ARAI Toshihiro Ishinomaki Senshu University School of Science & Engineering Professor, 理工学部, 教授 (10015745)
ONARI Seinosuke University of Tsukuba Institute of Applied Physics Professor, 物理工学系, 教授 (70015824)
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| Project Period (FY) |
1995 – 1996
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| Keywords | Amorphous Semiconductors / Glass Transition / Heat Capacity / Raman Scattering / Hierarchy / Cooperative Phenomena / Fracton |
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| Research Abstract |
The structural relaxation in the glass transition for various chalcogenide amorphous semiconductors (As_2S_3, As_xSe_<1-x> (0*x*0.4), (As_2S_3) _<100-x>Ag_x (0*x*6), (GeS_2) _<1-x> (Sb_2S_3) _x (x*0.33), Ge_xS_<1-x> (0.07*x*0.37), Se loaded into zeolites) has been investigated with the heat capacity data obtained on differential scanning calorimetry experiments. The heat capacity curves were analyzed by the Moynihan formulation with a KWW relaxation function phi (t) -exp [- (t/tau) ^<beta>]. It has been found that the nonexponentiality beta decreases linearly with a decrease in fictive temperature during annealing, and the configurational constraints increase with annealing so that the structural relaxation becomes more cooperative. The observation can be understood in terms of a hierarchical energy landscape, suggesting that the hierarchical distribution of energy barriers is one of important aspects for the understanding of the dynamics of the structural relaxation. Analyzes of the K
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WW-behavior on the structural relaxation of glass transition for various amorphous semiconductors with different dimensionality and local structures suggest that the KWW-behavior depends strongly on the underlying geometry (e.g.dimensionality, anisotropy, fractal). We have also found that the glass transition temperature and the activation energy for the glass transition of a-Se are remarkably modified when Se is incorporated in zeolites. They depends strongly on the pore size (window diameter of zeolites). The result implies that the dynamics of the structural relaxation in the glass transition of a-Se is significantly influenced by the geometrical restriction in the zeolites and by the absence of inter-cluster interaction. We determined fractal dimensions for Ge_xS_<1-x> system by applying a fracton model to the non-Debye-like vibrational excitation obtained from the low temperature low frequency Raman spectra, and found that the nonexponentiality beta of the structural relaxation of glass transition is strongly correlated with the fractal dimension. This is the evidence that the dynamics of glass transition (structural relaxation of supercooled liquid) rules over the static pattern of glassy structure. Less
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Research Products
(22 results)
