Self-organization in network glasses

Thorpe, M. F.; Jacobs, Donald J.; Chubynsky, Mykyta V.; Phillips, J. C.

doi:10.1016/s0022-3093(99)00856-x

Cited by 266 publications

(341 citation statements)

References 18 publications

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“…For x > x p , though no significant changes are observed in E a , indicating cessation of the kinetic evolution, the structural de-optimization manifests in the cooperative dynamics as indicating another distinct phase. This may well be the recently predicted intermediate phase, based on theoretical treatment of CRN-variants by Thorpe and Phillips,34) taking into account the fluctuations from a mean-field behaviour, and probably manifested in recent high-resolution Raman experiments. 35) The competition between attainment of a rigidly connected quasi-3D network and its changeover into relatively fragile quasi-2D network seems to endow the x p = 0.2 composition with a "saddle point" character, that conforms most to the Arrhenicity as regards its thermokinetics.…”

Section: Resultssupporting

confidence: 64%

Thermo-Kinetic Anomalies across Rigidity Threshold in GexSe1-x

Awasthi

Sampath

2002

Mater. Trans.

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We have investigated the glass-transition kinetics of nine Ge x Se 1−x glasses by differential scanning calorimetry. Relation between the drive (heating-rate q) and response (heatflow shift ∆H at T g ) is seen to be strictly linear only for GeSe 4 , 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(Se 1/2 ) 4 tetrahedral clusters, and subsequently interconnecting by edge-shared configurations to realize a random pearl-necklace 3-D covalent network.

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Section: Resultssupporting

confidence: 64%

Thermo-Kinetic Anomalies across Rigidity Threshold in GexSe1-x

Awasthi

Sampath

2002

Mater. Trans.

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“…Many amorphous materials possess an isostatic state, including fiber networks, covalent glasses, foams, and emulsions. Hence the viscoelasticity of damped random networks, which remains poorly understood, could provide insight into a broad class of materials, including the relationship between structure and response [2][3][4][5][6][7][8][9][10][11][12][13][14].…”

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confidence: 99%

Dynamic Critical Response in Damped Random Spring Networks

Tighe

2012

Phys. Rev. Lett.

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The isostatic state plays a central role in organizing the response of many amorphous materials. We construct a diverging length scale in nearly isostatic spring networks that is defined both above and below isostaticity and at finite frequencies and relate the length scale to viscoelastic response. Numerical measurements verify that proximity to isostaticity controls the viscosity, shear modulus, and creep of random networks. DOI: 10.1103/PhysRevLett.109.168303 PACS numbers: 83.60.Bc, 63.50.Àx, 64.60.Ht Random networks of springs display two distinct phases distinguished by the presence or absence of floppy modes-zero frequency motions that neither compress nor stretch springs. Floppiness is related to network structure via the mean coordination z [1,2]; networks with floppy modes reside below the isostatic coordination z c . Many amorphous materials possess an isostatic state, including fiber networks, covalent glasses, foams, and emulsions. Hence the viscoelasticity of damped random networks, which remains poorly understood, could provide insight into a broad class of materials, including the relationship between structure and response [2][3][4][5][6][7][8][9][10][11][12][13][14].One dramatic impact of floppiness on response is apparent in the compliance JðsÞ ¼ s ðsÞ= 0 (Fig. 1), which measures the Laplace-transformed shear strain ðsÞ accrued after a small step stress 0 . At short times, networks creep forward with an evolving strain rate. At long times or small s, hypostatic networks below z c flow steadily (J $ 1=s), while hyperstatic networks above z c approach constant strain (J $ s 0 ). Thus networks with floppy modes are fluids, and those without are solids. The shifting curves in Fig. 1 indicate that elasticity and viscosity vary with proximity to z c . Consistent with prior work on networks [5,6,[11][12][13][14], these data strongly suggest that the isostatic state is a nonequilibrium critical point. We will show that the distance to isostaticity Áz z À z c indeed controls viscoelasticity in random spring networks, as it does in soft sphere packings [9,15].One expects to find a diverging length scale near a critical point [16]. While hyperstatic networks are known to possess an isostatic length ' Ã $ 1=Áz, it only governs quasistatic response above z c [17][18][19][20][21]. The isostatic length should have a generalization AE ðÁz; !Þ that is valid not only above z c but also below and at finite frequency ! (or rate s). Here we demonstrate how to construct AE and show that it is the size of a finite system in which elastic storage and viscous loss balance. We also relate AE to response functions such as JðsÞ and the complex shear modulus G Ã ð!Þ. We find their rate and frequency dependence matches those of jammed solids, biopolymer networks, and athermal suspensions [7,9,10].Random spring networks.-Maxwell's counting argument gives the critical coordination z c ¼ 2d for central force networks in d dimensions [1,2]. We generate networks near z c according to the protocol of Ref. [6]. Beginning with ...

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“…Boolchand et. al. suggested that chalcogenide glasses display three elastic phases as a function of their mean coordination number: floppy phase, Intermediate phase (IP) and stressed rigid phase (Fig 2) [ [10][11][12][13][14][15][16][17][18][19][20][21][22]. Glass compositions in floppy phase and stressed rigid phase are usually poor glass formers due to the high internal stress in their molecular structure.…”

Section: Chalcogenide Materialsmentioning

confidence: 99%

Non-volatile Memory Devices Based on Chalcogenide Materials

Wang

2009

2009 Sixth International Conference on Information Technology: New Generations

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Self-organization in network glasses

Cited by 266 publications

References 18 publications

Thermo-Kinetic Anomalies across Rigidity Threshold in Ge<SUB>x</SUB>Se<SUB>1-x</SUB>

Thermo-Kinetic Anomalies across Rigidity Threshold in Ge<SUB>x</SUB>Se<SUB>1-x</SUB>

Dynamic Critical Response in Damped Random Spring Networks

Non-volatile Memory Devices Based on Chalcogenide Materials

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