The size of cooperatively rearranging regions at the glass transition

Donth, E.

doi:10.1016/0022-3093(82)90089-8

Cited by 578 publications

(445 citation statements)

References 13 publications

Supporting

Mentioning

424

Contrasting

Unclassified

Order By: Relevance

“…The size of CRR obtained for PVAc at T g , ξ ≈ 1.7nm agrees almost quantitatively with the characteristic length scale obtained by Berthier et al [5] by means of multipoint dynamical susceptibility (ξ ≈ 2nm). The size of CRR obtained by us for PS is also in qualitative agreement with that estimated by Hempel et al [29] in the framework of Donth approach [2] (ξ ≈ 2.2nm vs. ξ ≈ 3nm) and in excellent agreement with that estimated by Sills et al [30] by means of nanoscale sliding friction (ξ ≈ 2.1nm). Our results are also compatible with the absence of finite size effects in confinement down to 5 nm [31].…”

supporting

confidence: 91%

“…In this framework, more than forty years ago Adam and Gibbs [1] theorized that such a pronounced temperature dependence of the structural correlation time is due to a cooperative process involving several basic structural units forming cooperatively rearranging regions (CRR), which size increases with decreasing temperature. Since then a great deal of theoretical approaches [2,3] as well as simulation studies [4] and very recently experimental studies employing multipoint dynamical susceptibilities [5] have been devoted in the search of good candidates for CRR as well as its size and temperature dependence. All of these studies suggest that a growing correlation length with decreasing temperature of the order of several nanometers exists.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Route to calculate the length scale for the glass transition in polymers

2007

View full text Add to dashboard Cite

The occurrence of glass transition is believed to be associated to cooperative motion with a growing length scale with decreasing temperature. We provide a novel route to calculate the size of cooperatively rearranging regions CRR of glass-forming polymers combining the Adam-Gibbs theory of the glass transition with the self-concentration concept. To do so we explore the dynamics of glass-forming polymers in different environments. The material specific parameter α connecting the size of the CRR to the configurational entropy is obtained in this way. Thereby, the size of CRR can be precisely quantified in absolute values. This size results to be in the range 1 ÷ 3 nm at the glass transition temperature depending on the glass-forming polymer.PACS numbers: 64.70. Pf, 83.80.Tc, 83.80.Rs, 77.22.Gm The nature of the glass transition is one of the most important unsolved problems in condensed matter physics and research in this field has enormously intensified in the last decades due to its strong fundamental as well as applicative implications. Among the peculiar phenomena displayed by glass-forming liquids, the super-Arrhenius temperature dependence of the viscosity and the structural correlation time is certainly one of the most intriguing. In this framework, more than forty years ago Adam and Gibbs [1] theorized that such a pronounced temperature dependence of the structural correlation time is due to a cooperative process involving several basic structural units forming cooperatively rearranging regions (CRR), which size increases with decreasing temperature. Since then a great deal of theoretical approaches [2,3] as well as simulation studies [4] and very recently experimental studies employing multipoint dynamical susceptibilities [5] have been devoted in the search of good candidates for CRR as well as its size and temperature dependence. All of these studies suggest that a growing correlation length with decreasing temperature of the order of several nanometers exists. According to the Adam-Gibbs (AG) theory of the glass transition, the increase of the structural relaxation time with decreasing temperature, accompanied by the growth of the cooperative length scale, is due to the decrease of the number of configurations the glassformer can access, namely the configurational entropy (S c ) of the system. The connection between the structural relaxation time and S c is expressed by [1]:where C is a glass-former specific temperature independent parameter and τ 0 is the pre-exponential factor. The dynamics of a large number of glass forming systems have been successfully described through the AG equation in both experiments for low molecular weight glass formers [6] and polymers [7], as well as simulations [8]. Apart from the relation between the relaxation time and the configurational entropy, the AG theory provides a connection between the number of basic structural units belonging to the CRR and the configurational entropy: N ≈ S −1 . Several recent simulations studies, where the cooperative length scale and...

show abstract

supporting

confidence: 91%

mentioning

confidence: 99%

Route to calculate the length scale for the glass transition in polymers

2007

View full text Add to dashboard Cite

show abstract

“…21 Adam and Hibbs 22 introduced the concept of cooperative rearrangement of regions to unify these two views of glass transition. Donth 23 estimated the size of such cooperatively rearranging regions to be of the order of 10 Å for a number of glasses. When Se is confined between As 2 S 3 and the thickness of Se is comparable with the cooperative rearranging regions, it is possible to observe the quantum size effects on the glass transition temperature of Se.…”

Section: Discussionmentioning

confidence: 99%

Kinetics and chemical analysis of photoinduced interdiffusion in nanolayered Se/As2S3 films

Adarsh

Naik

Sangunni

et al. 2008

Journal of Applied Physics

View full text Add to dashboard Cite

We have studied the kinetics of photoinduced effects in nanolayered Se/ As 2 S 3 film by in situ optical absorption measurements, which reveal that photodarkening in these films is followed by photoinduced diffusion. An increase in disorder during photodarkening and its subsequent decrease during photoinduced diffusion were also observed. The observation of photodarkening of Se at room temperature when confined between As 2 S 3 layers suggests that the glass transition temperature of Se shifts to higher energy. The analysis shows that the atoms which take part in photodarkening play a vital role in photoinduced diffusion. The x-ray photoelectron spectroscopy measurements show the atomic movements during photoinduced diffusion. It also shows that some of the As-S bonds are converted into As-Se bonds. Since it is energetically difficult to break an As-S bond to form an As-Se bond, we assume that the new bond formations are taking place by the bond rearrangement mechanism.

show abstract

“…In general this is expected to have higher values for fragile glassformers because of their larger dynamical heterogeneity. This corresponds to larger CRRs for the soft glass, with widely distributed characteristic energy/time scales manifesting e.g., in non-Debyeian relaxation, in dielectric spectral hole burning, and in multi-dimensional NMR 26,27) Assuming the CRRs in the glass to have enough number of "particles" (N CRR , of heat capacity c each) for applying thermodynamic concepts, their mean temperature fluctuation is 28) δT 2 = k B T 2 /cN CRR . For T = T g this fluctuation is given by the half-width of the glass transition interval.…”

Section: Resultsmentioning

confidence: 99%

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

Awasthi

Sampath

2002

Mater. Trans.

View full text Add to dashboard Cite

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.

show abstract

The size of cooperatively rearranging regions at the glass transition

Cited by 578 publications

References 13 publications

Route to calculate the length scale for the glass transition in polymers

Route to calculate the length scale for the glass transition in polymers

Kinetics and chemical analysis of photoinduced interdiffusion in nanolayered Se/As2S3 films

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

Contact Info

Product

Resources

About