The Modified Random Network (MRN) Model within the Configuron Percolation Theory (CPT) of Glass Transition

Ojovan, Michael I.

doi:10.3390/ceramics4020011

Cited by 22 publications

(19 citation statements)

References 66 publications

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“…Glasses are isotropic and homogeneous at the macroscopic scale; however, the structure of glasses comprises the following attributes: (i) short-range order (SRO) with molecular-type units, i.e., building blocks, such as tetrahedral structures in silicates at the atomic scale; (ii) medium-range order (MRO) at a larger size range, which extends from second- and third-neighbor environments to percolating and fractal structures; and (iii) a disordered state (DS), which is homogeneous and isotropic, as observed at macroscopic sizes [ 22 , 32 , 33 ]. A diverse variety of glasses exist with a wide range of structural SRO building blocks from which the DS is composed of.…”

Section: Introductionmentioning

confidence: 99%

On Structural Rearrangements Near the Glass Transition Temperature in Amorphous Silica

Ojovan

Tournier

2021

Materials

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The formation of clusters was analyzed in a topologically disordered network of bonds of amorphous silica (SiO2) based on the Angell model of broken bonds termed configurons. It was shown that a fractal-dimensional configuron phase was formed in the amorphous silica above the glass transition temperature Tg. The glass transition was described in terms of the concepts of configuron percolation theory (CPT) using the Kantor-Webman theorem, which states that the rigidity threshold of an elastic percolating network is identical to the percolation threshold. The account of configuron phase formation above Tg showed that (i) the glass transition was similar in nature to the second-order phase transformations within the Ehrenfest classification and that (ii) although being reversible, it occurred differently when heating through the glass–liquid transition to that when cooling down in the liquid phase via vitrification. In contrast to typical second-order transformations, such as the formation of ferromagnetic or superconducting phases when the more ordered phase is located below the transition threshold, the configuron phase was located above it.

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Section: Introductionmentioning

confidence: 99%

On Structural Rearrangements Near the Glass Transition Temperature in Amorphous Silica

Ojovan

Tournier

2021

Materials

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“…It is also notable that the Wendt-Abraham criterion supposed that at T g the equality holds Φ T g = 0.15 [38]. This however is not always an exact relationship [49] and one can see from Figure 4a that for the amorphous Cu we get Φ T g = 0.1, whilst using the original Wendt-Abraham criterion we obtain a significantly overestimated T g . We also emphasise that the decrease of the coordination number with the increase of temperature alone cannot explain the glass transition because such changes can be caused by rearrangements of crystalline lattice and the change of FSDM is the crucial parameter to be checked for eventual changes signalling on phase transformations in amorphous materials.…”

Section: Discussionmentioning

confidence: 87%

On Structural Rearrangements during the Vitrification of Molten Copper

Ojovan

Louzguine‐Luzgin

2022

Materials

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We utilise displacement analysis of Cu-atoms between the chemical bond-centred Voronoi polyhedrons to reveal structural changes at the glass transition. We confirm that the disordered congruent bond lattice of Cu loses its rigidity above the glass transition temperature (Tg) in line with Kantor–Webman theorem due to percolation via configurons (broken Cu-Cu chemical bonds). We reveal that the amorphous Cu has the Tg = 794 ± 10 K at the cooling rate q = 1 × 1013 K/s and that the determination of Tg based on analysis of first sharp diffraction minimum (FDSM) is sharper compared with classical Wendt–Abraham empirical criterion.

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“…Each of these glass formers reacts with alkali metal oxides [88][89][90]; herein, the authors are predominantly concerned with Na 2 O. Varying the glass chemical composition alters the nearest-neighbor structures of the glass in regards to the coordination number of the boron atoms and the number of non-bridging oxygen atoms (see [2][3][4]12,19,20] for more details) in the silicate and borate networks. The network formed, beyond these nearest-neighbor structures, is usually described as interconnected rings of various sizes, denoted nMR (nmembered rings) (see [2][3][4]12,19,20,80,[108][109][110][111] for more details). The size and distribution of these nMR depends on the glass chemical composition along with fabrication protocols [112].…”

Section: The Medium-range Structure Of Aps-sbn Glassesmentioning

confidence: 99%

Stress Corrosion Cracking in Amorphous Phase Separated Oxide Glasses: A Holistic Review of Their Structures, Physical, Mechanical and Fracture Properties

Feng

Bonamy

Célarié

et al. 2021

CMD

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Stress corrosion cracking is a well-known phenomenon in oxide glasses. However, how amorphous phase separation (APS) alters stress corrosion cracking, and the overall mechanical response of an oxide glass is less known in literature. APS is a dominant feature concerning many multicomponent systems, particularly the ternary sodium borosilicate (SBN) glass systems. Its three constituent oxides have significant industrial relevance, as they are the principal components of many industrial oxide glasses. Simulations and experimental studies demonstrate the existence of a two-phase metastable miscibility gap. Furthermore, theory suggests the possibility of three-phase APS in these oxide glasses. Literature already details the mechanisms of phase separation and characterizes SBN microstructures. Realizing that glasses are structurally sensitive materials opens a number of other questions concerning how the mesoscopic APS affects the continuum behavior of glasses, including dynamic fracture and stress corrosion cracking. This paper reviews current literature and provides a synthetic viewpoint on how APS structures of oxide glasses alter physical, mechanical, dynamic fracture, and stress corrosion cracking properties.

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The Modified Random Network (MRN) Model within the Configuron Percolation Theory (CPT) of Glass Transition

Cited by 22 publications

References 66 publications

On Structural Rearrangements Near the Glass Transition Temperature in Amorphous Silica

On Structural Rearrangements Near the Glass Transition Temperature in Amorphous Silica

On Structural Rearrangements during the Vitrification of Molten Copper

Stress Corrosion Cracking in Amorphous Phase Separated Oxide Glasses: A Holistic Review of Their Structures, Physical, Mechanical and Fracture Properties

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