Revealing ordering and structural changes at glass transition

Ojovan, Michael I.

doi:10.1557/opl.2013.112

Cited by 6 publications

(4 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Applying Eq. ( 7),  ls0 corresponds to a Lindemann constant equal to 0.103, which is in good agreement with other determinations [21][22][23]. Then, the enthalpy saving coefficient cannot be smaller than 0.217.…”

Section: The Lindemann Constant Of Pure Liquid Elementssupporting

confidence: 89%

Lindemann's rule applied to the melting of crystals and ultra-stable glasses

Tournier

2016

Chemical Physics Letters

View full text Add to dashboard Cite

The ratio of the mean square amplitude root of thermal vibrations and the interatomic distance is a universal constant  ls at the melting temperature T m . The classical Gibbs free energy change completed by a volume energy saving  ls (or  lg )×H m that governs the liquid to solid and liquid to ultrastable glass transformations leads to a universal constant equal to  ls (or  lg ), H m being the crystal melting enthalpy. The minimum values 0.217 of  ls and 0.103 of  ls are used to predict ultra-stable glass formation in pure metallic liquid elements at a universal reduced temperature  g = (T g T m )/T m = 0.6223. 1-IntroductionThe dependence of the liquid supercooling temperature on the superheating rate shows the existence of long-lived metastable nuclei surviving above the melting temperature T m [1]. The classical Gibbs free energy change cannot predict the presence of such entities without introducing a complementary negative contribution v×p varying with  2 = (T-T m ) 2 /T 2 m , v being the nucleus volume and p a complementary Laplace pressure [2,3]. Crystallisation and melting are initiated by the formation of solid or liquid growth nuclei accompanied by a volume change that is expected to obey to Lindemann's rule [4]. Lindemann's description shows that the ratio of the mean square amplitude root of thermal vibrations and the interatomic distance is a universal constant ls at the melting temperature T m .The critical complement v×p associated with crystallisation at T = T m has been determined for many pure liquid elements and glass-forming melts as being equal to v× ls0 ×H m /V m with ls0 being a numerical critical fraction of the melting heat H m . The coefficient  ls0 = 0.217 is the same for many liquid elements [2], while it is much larger than 1 and smaller than 2 in many glass-forming melts, as shown for 84 examples Tables 2 and 3 in [5]. The objective of this study is to relate  ls0 to the Lindemann ratio ls .The ultra-stable glass state is described as a thermodynamic equilibrium between crystal and liquid states, which would be attained by supercluster formation and their percolation after a very long annealing time at the Kauzmann temperature T K [5], or by quenching the melt from above T m and annealing it at the formation temperature T sg of this phase [6]. The optimum formation temperature T sg leading to the higher density is always equal to the Kauzmann temperature of strong glasses, and very often to that of fragile glasses. The enthalpy that is recovered at the glass transition temperature T g is equal to ( ls0 - gs0 )×H m in strong glasses and to 1.5×( ls0 - gs0 )×H m in fragile glasses with  gs0 being the critical fraction of melting heat leading to crystallisation of a virtual glass at T m . This description agrees, in principle, with the Cite as arXiv : 1511.07984 [cond-mat.mtrl-sci] or

show abstract

Section: The Lindemann Constant Of Pure Liquid Elementssupporting

confidence: 89%

Lindemann's rule applied to the melting of crystals and ultra-stable glasses

Tournier

2016

Chemical Physics Letters

View full text Add to dashboard Cite

show abstract

“…Also, intensification of a covalent bonding between metallic atoms and P was found in Pd-Cu-Ni-P melts cooled in situ close to the glass-transition region [68,93] which was responsible for the changes in the structure of a liquid (clustering, [94] ), and thus, fragile behavior of this melt. Fragile liquids are generally predisposed to have lower GFA compared to strong liquids [95].…”

Section: Discussionmentioning

confidence: 96%

Role of different factors in the glass-forming ability of binary alloys

et al. 2014

View full text Add to dashboard Cite

International audienceIn the present work, we discuss the glass-forming ability of various binary alloys in which the glassy phase was not formed even by melt spinning technique with high cooling rate of the melt up to 1 MK/s (some consisted of partly glassy phase), though by commonly accepted guidelines, these alloys could be as good glass-formers as many other binary glasses. The alloys studied belong to binary systems with multiple eutectics; the constituent elements have a negative enthalpy of mixing, and a significant variability of atomic size differences is observed from system to system. The results indicate the necessity of taking into account simultaneously various factors influencing the glass-forming ability including melt fragility

show abstract

“…is given by the universal Scher–Zallen critical density ϕ c = 0.15 ± 0.01, which results in calculated T g practically coinciding with that measured in experiments . However, more complex, for example, fragile materials are characterized by material‐dependent and significantly smaller percolation thresholds . Numerical calculations require thermodynamic parameters of the network, for example, enthalpies and entropies of bonds.…”

Section: Introductionmentioning

confidence: 56%

“…Indeed, the glass transition shows distinctly thermodynamic phase transition features; however, being a kinetically controlled phenomenon, the glass transition exhibits a range of T g , which depends on the cooling rate with maximal T g at highest rates of cooling . A theoretical description of glass transition is possible based on percolation theory approach using either rigidity percolation model or connectivity percolation, for example configuron percolation theory (CPT) . The CPT uses Angell disordered bond lattice (network) when the system of strongly interacting ions can be replaced by a new congruent system of weakly interacting bonds .…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic Parameters of Bonds in Glassy Materials from Shear Viscosity Coefficient Data

Ojovan

2014

Int J of Appl Glass Sci

Self Cite

View full text Add to dashboard Cite

A simple analytical approach is proposed that provides numerical values of thermodynamic parameters of bonds (enthalpy and entropy of formation) in glassy materials from four shear viscosity coefficient data at four temperatures, two of which should be below Tg and other two above Tg. This method replaces complex fitting procedures for the nonlinear viscosity equations to experimental data and provides accurate data close to that obtained from fitting procedures. It can be also used for obtaining zero estimates of unknown parameters for the nonlinear least squares regression procedures.

show abstract

Revealing ordering and structural changes at glass transition

Abstract: Ordering types in the disordered structure of amorphous materials and structural changes which occur at glass-liquid transition are discussed revealing medium range order and reduction of topological signature of bonding system.

Cited by 6 publications

References 23 publications

Lindemann's rule applied to the melting of crystals and ultra-stable glasses

Lindemann's rule applied to the melting of crystals and ultra-stable glasses

Role of different factors in the glass-forming ability of binary alloys

Thermodynamic Parameters of Bonds in Glassy Materials from Shear Viscosity Coefficient Data

Contact Info

Product

Resources

About