Sylwester J. Rzoska

Bio: Sylwester J. Rzoska is an academic researcher from Polish Academy of Sciences. The author has contributed to research in topic(s): Dielectric & Glass transition. The author has an hindex of 33, co-authored 216 publication(s) receiving 3570 citation(s). Previous affiliations of Sylwester J. Rzoska include University of Silesia in Katowice & Silesian University.

Discovery of Ultra-Crack-Resistant Oxide Glasses with Adaptive Networks

Abstract: Despite their transformative role in our society, oxide glasses remain brittle. Although extrinsic postprocessing techniques can partially mitigate this drawback, they come with undesirable side effects. Alternatively, topological engineering offers an attractive option to enhance the intrinsic strength and damage resistance of glass. On the basis of this approach, we report here the discovery of a novel melt-quenched lithium aluminoborate glass featuring the highest crack resistance ever reported for a bulk oxide glass. Relying on combined mechanical and structural characterizations, we demonstrate that this unusual damage resistance originates from a significant self-adaptivity of the local atomic topology under stress, which, based on a selection of various oxide glasses, is shown to control crack resistance. This renders the lithium aluminoborate glass a promising candidate for engineering applications, such as ultrathin, yet ultrastrong, protective screens.

Structure and mechanical properties of compressed sodium aluminosilicate glasses: Role of non-bridging oxygens

Abstract: Clarifying the effect of pressure on the structure of aluminosilicate glasses is important for understanding the densification mechanism of these materials under pressure and the corresponding changes in macroscopic properties. In this study, we examine changes in density, network structure, indentation hardness, and crack resistance of sodium aluminosilicate glasses with varying Al/Si ratio and thus non-bridging oxygen (NBO) content before and after 1 GPa isostatic compression at elevated temperature. With increasing NBO content, the silicate network depolymerizes, resulting in higher atomic packing density, lower hardness, and higher crack resistance. The ability of the glasses to densify under isostatic compression is higher in the high-NBO glasses, and these glasses also exhibit more pronounced pressure-induced changes in mechanical properties. The 27Al NMR data show a surprising presence of five-fold aluminum in the as-made high-NBO glasses, with additional formation upon compression. Our study therefore provides new insights into the complicated relationship between Al coordination and NBO content in aluminosilicate glasses and how it affects their densification behavior.

Temperature and volume effects on the change of dynamics in propylene carbonate.

Abstract: Dielectric relaxation and PVT measurements were carried out on propylene carbonate. From these, we show that thermal energy exerts a stronger influence than volume on the temperature dependence of the dynamic properties. Data obtained at all temperatures and pressures superimpose, when expressed as a function of T ˛1 V ˛3.7 . The scaling exponent is consistent with more thermally governed dynamics, and can be interpreted as a reflection of the soft nature of the potential. The change of dynamics observed in the conductivity and relaxation data transpires at a fixed value of either quantity, independent of temperature and pressure.

Changes in dynamic crossover with temperature and pressure in glass-forming diethyl phthalate.

Abstract: Dielectric relaxation measurements have been used to study the crossover in dynamics with temperature and pressure, onset of breakdown of the Debye-Stokes-Einstein law, and the relation between the \ensuremath{\alpha} and the \ensuremath{\beta} relaxations in diethyl phthalate. The measurements made over 10 decades in frequency and a broad range of temperature and pressure enable the dc conductivity and the \ensuremath{\alpha}- and the \ensuremath{\beta}-relaxations to be studied altogether. The isobaric data show that the \ensuremath{\alpha}-relaxation time ${\ensuremath{\tau}}_{\ensuremath{\alpha}}$ has temperature dependence that crosses over from one Vogel-Fulcher-Tammann-Hesse form to another at ${T}_{B}\ensuremath{\approx}227\mathrm{K}$ and ${\ensuremath{\tau}}_{\ensuremath{\alpha}}\ensuremath{\approx}{10}^{\ensuremath{-}2}\mathrm{s}.$ The dc conductivity \ensuremath{\sigma} exhibits similar crossover at the same ${T}_{B}.$ At temperatures above ${T}_{B},$ ${\ensuremath{\tau}}_{\ensuremath{\alpha}}$ and \ensuremath{\sigma} have the same temperature dependence, but below ${T}_{B}$ they become different and the Debye-Stokes-Einstein law breaks down. The breadth of the \ensuremath{\alpha} relaxation is nearly constant for $Tl{T}_{B},$ but decreases with increasing temperature for $Tg{T}_{B}.$ The time dependence of ${\ensuremath{\tau}}_{\ensuremath{\beta}}$ is Arrhenius, which when extrapolated to higher temperatures intersects ${\ensuremath{\tau}}_{\ensuremath{\alpha}}$ at ${T}_{\ensuremath{\beta}}$ nearly coincident with ${T}_{B}.$ Isothermal measurements at various applied pressures when compared with isobaric data show that the shape of the \ensuremath{\alpha}-relaxation depends only on ${\ensuremath{\tau}}_{\ensuremath{\alpha}},$ and not on the T and P combinations. At a constant temperature, while ${\ensuremath{\tau}}_{\ensuremath{\alpha}}$ increases rapidly with pressure, the \ensuremath{\beta}-relaxation time ${\ensuremath{\tau}}_{\ensuremath{\beta}}$ is insensitive to applied pressure. This behavior is exactly the same as found in ${1,1}^{\ensuremath{'}}$-bis (p-methoxyphenyl) cyclohexane. The findings are discussed in the framework of the coupling model.

Critical phenomena and renormalization-group theory

Abstract: We review results concerning the critical behavior of spin systems at equilibrium. We consider the Ising and the general O ( N )-symmetric universality classes, including the N →0 limit that describes the critical behavior of self-avoiding walks. For each of them, we review the estimates of the critical exponents, of the equation of state, of several amplitude ratios, and of the two-point function of the order parameter. We report results in three and two dimensions. We discuss the crossover phenomena that are observed in this class of systems. In particular, we review the field-theoretical and numerical studies of systems with medium-range interactions. Moreover, we consider several examples of magnetic and structural phase transitions, which are described by more complex Landau–Ginzburg–Wilson Hamiltonians, such as N -component systems with cubic anisotropy, O ( N )-symmetric systems in the presence of quenched disorder, frustrated spin systems with noncollinear or canted order, and finally, a class of systems described by the tetragonal Landau–Ginzburg–Wilson Hamiltonian with three quartic couplings. The results for the tetragonal Hamiltonian are original, in particular we present the six-loop perturbative series for the β -functions. Finally, we consider a Hamiltonian with symmetry O ( n 1 )⊕ O ( n 2 ) that is relevant for the description of multicritical phenomena.

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

Abstract: 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; ...

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

Abstract: 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

Evaluation of amorphous solid dispersion properties using thermal analysis techniques.

Abstract: Amorphous solid dispersions are an increasingly important formulation approach to improve the dissolution rate and apparent solubility of poorly water soluble compounds. Due to their complex physicochemical properties, there is a need for multi-faceted analytical methods to enable comprehensive characterization, and thermal techniques are widely employed for this purpose. Key parameters of interest that can influence product performance include the glass transition temperature (T(g)), molecular mobility of the drug, miscibility between the drug and excipients, and the rate and extent of drug crystallization. It is important to evaluate the type of information pertaining to the aforementioned properties that can be extracted from thermal analytical measurements, in addition to considering any inherent assumptions or limitations of the various analytical approaches. Although differential scanning calorimetry (DSC) is the most widely used thermal analytical technique applied to the characterization of amorphous solid dispersions, there are many established and emerging techniques which have been shown to provide useful information. Comprehensive characterization of fundamental material descriptors will ultimately lead to the formulation of more robust solid dispersion products.