Critical phenomena and renormalization-group theory

Dynamic properties, derived from dielectric relaxation spectra of glass-formers at variable temperature and pressure, are used to characterize and classify any resolved or unresolved secondary relaxation based on their different behaviors. The dynamic properties of the secondary relaxation used include: (1) the pressure and temperature dependences; (2) the separation between its relaxation time τβ and the primary relaxation time τα at any chosen τα; (3) whether τβ is approximately equal to the independent (primitive) relaxation time τ0 of the coupling model; (4) whether both τβ and τ0 have the same pressure and temperature dependences; (5) whether it is responsible for the “excess wing” of the primary relaxation observed in some glass-formers; (6) how the excess wing changes on aging, blending with another miscible glass-former, or increasing the molecular weight of the glass-former; (7) the change of temperature dependence of its dielectric strength Δeβ and τβ across the glass transition temperature Tg; ...

Classification of secondary relaxation in glass-formers based on dynamic properties.

An intriguing problem in condensed matter physics is understanding the glass transition, in particular the dynamics in the equilibrium liquid close to vitrification Recent advances have been made by using hydrostatic pressure as an experimental variable These results are reviewed, with an emphasis in the insight provided into the mechanisms underlying the relaxation properties of glass-forming liquids and polymers

https://iopscience.iop.org/article/10.1088/0034-4885/68/6/R03/pdf

Supercooled dynamics of glass-forming liquids and polymers under hydrostatic pressure

Evaluation of amorphous solid dispersion properties using thermal analysis techniques.

/pdf/dislocations-in-solids-1gaufoliyg.pdf

Dislocations in solids

Near-continuous isotropic – nematic transition in compressed rod-like liquid crystal based nanocolloid

In this report we present the first ever results of strong pretransitional effect observed for the maximum of absorption peak εmax ′′ (T) in supercooled liquid-crystalline systems near the glass transition temperature. This anomaly may be described by critical-like relation with critical exponent α = 0.5, which corresponds well with previous results for static electric permittivity εs(T). Such a behaviour may suggest thermodynamic character of glass transition. The description of the glass transition as a typical phase transition is still a subject of academic debate [1-4]. On the one hand, it is believed that the glass transition is a continuous transition, which begins at the temperature Tg and ends only around the Kauzmann temperature. There is still insufficient experimental evidence to unambiguously define its character. Colby and Erwin found that the dynamics of the transition to the glass state is related to the critical point (Tc) below Tg [5,6]. Then Tanaka [7] created a model in which he assumed that in each liquid there is a tendency to local aggregation of the bond-ordering and / or density

Strong pretransitional anomaly near glass transition

Abstract We consider history-dependent behavior in domain-type configurations in orientational order that are formed in configurations reached via continuous symmetry-breaking phase transitions. In equilibrium, these systems exhibit in absence of impurities a spatially homogeneous order. We focus on cases where domains are formed via (i) Kibble-Zurek mechanism in fast enough quenches or by (ii) Kibble mechanism in strongly supercooled phases. In both cases, domains could be arrested due to pinned topological defects that are formed at domain walls. In systems exhibiting polar or quadrupolar order, point and line defects (disclinations) dominate, respectively. In particular, the disclinations could form complex entangled structures and are more efficient in stabilizing domains. Domain patterns formed by fast quenches could be arrested by impurities imposing a strong enough random-field type disorder, as suggested by the Imry-Ma theorem. On the other hand, domains formed in supercooled systems could be also formed if large enough energy barriers arresting domains are established due to large enough systems’ stiffness. The resulting effective interactions in established domain-type patterns could be described by random matrices. The resulting eigenvectors reveal expected structural excitations formed in such structures. The most important role is commonly played by the random matrix largest eigenvector. Qualitatively different behavior is expected if this eigenvector exhibits a localized or extended character. In the former case, one expects a gradual, non-critical-type transition into a glass-type structure. However, in the latter case, a critical-like phase behavior could be observed. Graphical abstract 

/pdf/history-dependent-phase-transition-character-2rkovtuh.pdf

Sylwester J. Rzoska

Papers

Near-continuous isotropic – nematic transition in compressed rod-like liquid crystal based nanocolloid

Strong pretransitional anomaly near glass transition

History-dependent phase transition character