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Home  >  Journal list  >  MATERIALS TRANSACTIONS  >  Vol.43  No.8 (2002)  >  pp.2046-2049

MATERIALS TRANSACTIONS
<<Previous article Vol.43  No.8 (2002)   pp.2046 - 2049 Next article>>

Thermo-Kinetic Anomalies across Rigidity Threshold in GexSe1-x

Anand M. Awasthi1) and Sujatha Sampath2)
1) Inter University Consortium for DAE Facilities University Campus
2) IPNS Division, Argonne National Laboratory


We have investigated the glass-transition kinetics of nine GexSe1−x glasses by differential scanning calorimetry. Relation between the drive (heating-rate q) and response (heatflow shift ΔH at Tg) is seen to be strictly linear only for GeSe4, known to signify the bulk-rigidity threshold for this series. From an Arrhenius analysis the activation energies for glassy relaxation are estimated, and point to the existence of different thermokinetic phases below and above the threshold composition. Series behaviour of the kinetic activation is conciled to a concurring one seen in the size of cooperatively diffusing regions. The anomalies are attributed to structural crossovers with Ge doping; first from the parent uniform Se-chains to that of backbones out-branching at corner-shared Ge(Se1⁄2)4 tetrahedral clusters, and subsequently interconnecting by edge-shared configurations to realize a random pearl-necklace 3-D covalent network.


Keyword:
rigidity percolation, glasses, differential scanning calorimetry.

Received: February 18, 2002
Accepted: March 12, 2002 , Published online: September 06, 2005
Copyright (c) 2005 The Japan Institute of Metals

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