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The long-range supercritical changes of dielectric constant, resembling ones observed in the isotropic phase of rod-like liquid crystalline compounds, are evidenced on approaching liquid-solid discontinuous phase transition. The 'supercriticality' can be an additional factor for supporting the unique pro-health properties of linseed oil. It can also be significant for numerous technological applications. The report also reveals properties significant for melting/freezing discontinuous phase transition cognitive puzzle. Broadband dielectric spectroscopy studies revealed long-range premelting (heating from the solid phase) and post-freezing (cooling from the liquid phase) effects with critical-like parametrizations. They can be correlated with the 'grain model' for premelting and its development by the Lipovsky model. The evidence for the post-freezing effect, with the critical-like portrayal, may indicate a specific granular solidification associated with pretransitional fluctuations. Numerous hallmarks of liquid-liquid and solid-solid phase transitions have also been found. Notably, the melting temperature surrounding is related to the minimum and the freezing temperature to the maximum of dielectric loss factor D=tan(delta). Regarding dynamics, three primary relaxation processes have been found. Their changes in subsequent temperature intervals, related to the apparent activation enthalpy, follow critical-like patterns with the same singular temperature. For relaxation times evolution, it leads to optimal parameterizations via the 'critical and activated' equation, recently proposed., Comment: 14 Figures , 15 equations

The model discussion focused on links between the unique properties of relaxor ceramics and the basics of critical phenomena physics and glass transition physics. It indicates the significance of uniaxiality for appearing mean-field features near paraelectric_ferroelectric transition. Pretransitional fluctuations, increasing up to grain size and leading to inter-grain, random, local electric fields, are indicated to be responsible for relaxor ceramics characteristics. Their impacts yield the pseudo spinodal behavior associated with weakly discontinuous local phase transitions. The emerging model redefines the meaning of the Burns temperature and polar nanoregions PNRs. It explains coherently dielectric constant changes with the diffused maximum near paraelectric_ferroelectric transition, the sensitivity even to moderate electric fields, tunability, and the glassy dynamics. These considerations are confronted with experimental results for the complex dielectric permittivity studies in relaxor ceramic, covering the 200K range, from the paraelectric to the deep ferroelectric phase. The distortions-sensitive and derivative-based analysis revealed the preference for the exponential scaling pattern in the paraelectric phase and the surroundings of the paraelectric-ferroelectric transition. It may suggest the Griffith phase behavior associated with the mean-field criticality disturbed by random local impacts. The discussion of experimental results is supplemented by relaxation times changes and the coupled energy losses analysis. The studies also led to the description of tunability temperature changes with scaling relations., Comment: 39 PAGES, 20 Figures

Landau - de Gennes mean field model predicts the discontinuous transition for the Isotropic - Nematic transition, associated with uniaxial and quadrupolar order parameter in three dimensions. This report shows pressure-related dielectric studies for rod-like nematogenic pentylcyanobiphenyl (5CB) and its nanocolloids with BaTiO3 nanoparticles. The scan of dielectric constant revealed the continuous I-N transition in a compressed nanocolloid with a tiny amount of nanoparticles (x=0.1%). For the nematic phase in 5CB and its x=1% nanocolloid the enormous values of dielectric constant and the bending-type long-range pretransitional behavior were detected. The 'shaping' influence of pretransitional fluctuations was also detected for the ionic-related contribution to dielectric permittivity in the isotropic phase. For the high-frequency relaxation domain, this impact was tested for the primary relaxation time and the translational-orientaional decoupling., Comment: 28 pages, 7 figures

The report shows the temperature behavior of the real part of dielectric permittivity in the static (dielectric constant) and lo-frequency (LF) domains in bulk samples of 11CB and BaTiO3-based nanocolloids. The study covers the Isotropic Liquid (I), Nematic (N), Smectoc A (SmA) and Solid CRystal (Cr) phases. For each phase, the dominance of pretransitional fluctuations, significantly moderated by nanoparticles is shown. The authors consider separate focus on dielectric constant(Eps(T)) evolution in the static domain yielding mainly response from permanent dipole moments and their arrangement and in the low-frequency (LF) domain DeltaEps'(f)=Eps'(f)-Eps(where Eps'(f) is for the real part of dielectric permittivity in the LF domain).which is associated solely with ionic-related polarization mechanism. All these lead to new experimental evidence concerning I-N, N-SmA and SmA-Cr transitions.focusing on the strength and extent of pretransitional effects, critical exponents and phase transition discontinuities. The strong evidence for pretransitional effects near SmA-N transition is notable, particularly regarding DeltaEps'(f,T). Studies are supplemented by DC electric conductivity - the parameter also related to LF domain. Finally, the validity of the relation Eps'(f,T) = Af^(-3/2)+Eps (where f stands for the frequency and A is a constant parameter) often used for discussing dielectric spectra in LC compounds and its nanocollids in the LF domain, is examined., Comment: 29 pages, 12 figures

Melting/freezing are canonical examples of discontinuous phase transitions, for which no pretransitional effects in the liquid phase are expected.For the solid phase, weak premelting effects are evidenced. This report shows long-range, critical-like, pretransitional effect in liquid thymol detected in Electrooptic Kerr effect (EKE) studies. Notable is the negative sign of EKE pretransitional anomaly. Studies are supplemented by high-resolution by dielectric constant temperature-related scan, which revealed a weak premelting effect in the solid phase. Both EKE and dielectric constant show a 'crossover' change ca. 10K above the melting temperature. It can be recognized as the hallmark of the challenging Liquid-Liquid transition phenomenon ., Comment: 18 pages, 6 figures

Coexistence curves in mixtures of limited miscibility with the lower critical consolute temperature (LCT), of 3-picoline with deuterium oxide (D$_2$O), and D2O/H2O have been determined. They were tested with respect to the order parameter, the diameter of the binodal, and coordinates of the critical consolute point (critical temperature Tc and critical concentration fic) Studies were carried out using the innovative method based on the analysis of relative volumes occupied by coexisting phases, yielding high-resolution data. The clear violation of the Cailletet-Mathew law of rectilinear diameter for the LCT mixtures of limited miscibility is evidenced. For the order parameter, the new distortion-sensitive analysis method yielded the evidence for the model-value of the order parameter critical exponent beta = 0.326.up to ca. 1 K from Tc. Finally, the simple & easy method for determining the critical concentration by testing relative volumes of coexisting phases (or alternatively fractional meniscus heights, h) is presented. The significance of the invariant value hc(Tc, fic) = 1/2 is highlighted. The appearance of the milky & bluish critical opalescence is also shown, Comment: 19 pages, 8 figures

The report presents results that can be considered as the reference for innovative generations of Supercritical Fluids (SCF), Liquid-Liquid (LL), and Liquid (L) extraction technologies. They are related to implementations of Critical Phenomena Physics for such applications not considered so far. For the gas-liquid critical point, the shift from SuperCritical to SubCritical due to the additional exogenic impact of ultrasounds is indicated. For LL technology, the possibility of increasing process effectiveness when operating near the critical consolute point under pressure is indicated. Finally, the discovery of long-range precritical-type changes of dielectric constant in linseed oil, standing even 50K above the melting temperature, is presented. It suggests that the extraction process linking SCF and L features, and exploring natural carries such as linseed oil, is possible. The report recalls the fundamental base for the extraction process via Kirkwood and Noyes-Withney relations and presents their implementations to critical conditions, including pressure., Comment: 21 pages, 8 Figures

The lack of ultimate scaling relations for previtreous changes of the primary relaxation time or viscosity in glass-forming systems constitutes the grand fundamental challenge, also hindering the development of relevant material engineering applications. The report links the problem to the location of the previtreous domain remote from a hypothetical singularity. As the solution, the linearized, distortions-sensitive analysis is proposed. It is developed for scaling-relations linked to basic glass transition models: free volume, entropic, critical-like, avoided criticality, and kinetically constrained approaches. For all model scaling relations their alternative formulations based on fragility, the semi-universal metric of dynamics, are presented. The distortions-sensitive analysis is supplemented by the alternative approach based on the activation energy index showing its relative changes on cooling in the previtreous region. The search for the coherent description of the previtreous dynamics in the homologous series of polyols, from glycerol to sorbitol, is used to present in practice and validate the application of the distortions sensitive analysis. Only two scaling equation, MYEGA and the recent 'activation and critical' (AC), passed such exam. They also revealed a limited reliability of the Stickel operator' analysis for detecting the dynamic crossover. The report constitutes the unique tool-guide for applications, and a checkpoint analysis of the glass transition models. The discussion focuses on the temperature path on cooling but the extension for the still hardly discussed pressure path is also discussed.

This paper presents results for systems formed in a solid glassy state after nanocrystallization process above the glass temperature. We analyze electric conductivity and relaxation processes after such treatment under high temperature (HT) and high pressure (HP-HT) as well. The latter leads to ca. 8% increase of density, two decades (100) increase of electric conductivity as well as qualitative changes in relaxation processes. The previtreous-type changes of the relaxation time on cooling is analyzed by the use of critical-like and the 'critical-activated' description. Presented results correspond well with obtained for this material and shown in ref. [8]. The evidence for pressure evolution of the glass and crystallization temperatures, indicating the unique possibility of maxima and crossovers is also reported.

In this report we present the first ever results of strong pretransitional effect observed for the maximum of absorption peak $${\epsilon}_{max}^{''}(T)$$ in supercooled liquid-crystalline systems near the glass transition temperature. This anomaly may be described by critical-like relation with critical exponent {\alpha}=0.5, which corresponds well with previous results for static electric permittivity $${\epsilon}_{s}(T)$$. Such a behaviour may suggest thermodynamic character of glass transition.

In this letter we introduced a new scaling method based on Adam-Gibbs model. Moreover, generalised critical-like expression of configurational entropy S_C (T)=S_0 (1-T_K/T)^n is used. Obtained values of pseudocritical exponent n seem to be universal for studied systems and corresponds well with thermodynamic data. Relation between dynamic portrayal represented by primary relaxation time and thermodynamic (specific heat capacity) is in a good agreement.

The impact of pressure on the critical consolute temperature in nitrobenzene, nitrotoluene, and nitropropane plus n-alkanes from pentane to eicosane is discussed., Comment: 30 pages, 13 figures and 2 Tables

The previtreous dynamics in glass forming monomer, glycerol monoacrylate (GMA), using broadband dielectric spectroscopy (BDS) was tested. Measurements revealed the clear dynamic crossover at temperature $T_B = 254$ K and the time scale $\tau(T_B) = 5.4$ ns for the primary (structural) relaxation time and no hallmarks for the crossover for the DC electric conductivity $\sigma_{DC}$. This result was revealed via the derivative-based and distortions-sensitive analysis $dln{H_{a}}/d(1/T)$ vs. $1/T$, where $H_a$ is for the apparent activation energy. Subsequent tests of the fractional Debye-Stokes-Einsten relation $\sigma_{DC}(\tau_{\alpha})^S = const$ showed that the crossover is associated with $S = 1$ (for $T>T_B$)->$S = 0.84$ (for $T

The ways of portrayal of the pressure evolution of the glass temperature (Tg) beyond the dominated Simon-Glatzel-like pattern are discussed. This includes the possible common description of Tg(P) dependences in systems described by dtg/dP>0 and dTg/dP<0. The latter is associated with the maximum of Tg(P) curve hidden in the negative pressures domain. The issue of volume and density changes along the vitrification curve is also noted. Finally, the universal pattern of vitrification associated with the crossover from the low density (isotropic stretching) to the high density (isotropic compression) systems is proposed. Hypothetically, it may obey any glass former, from molecular liquids to colloids.

One of hallmark features of glass forming ultraviscous liquids is the decoupling between translational and orientational dynamics. This report presents studies of this phenomenon in glycerol, a canonical molecular glass former, heading for the impact of two exogenic factors: high pressures up to extreme 1.5 GPa and silver (Ag) nanoparticles (NP). The analysis is focused on the fractional Debye-Stokes-Einstein (FDSE) relation $\sigma(T,P)*(\tau(T,P))^S = const$, linking DC electric conductivity $(\sigma)$ and primary $(\alpha)$ relaxation time $(\tau_\alpha)$. In glycerol and its nanocolloid (glycerol with Ag-NP) under atmospheric pressure only the negligible decoupling $(S = 1)$ was detected. However, in the compressed nanocolloid a well-defined transformation (at P = 1.2 GPa) from $S \thickapprox 1$ to the very strongly decoupled dynamics $(S \thickapprox 0.5)$ occurred. For comparison, in pressurized 'pure' glycerol the stretched shift from $S \thickapprox 1$ to $S \thickapprox 0.7$ took place. This report presents also the general discussion of FDSE behavior in ultraviscous liquids, including the new link between FDSE exponent, fragility and the apparent activation enthalpy and volume.

Orientational and translational decouplings in ultraviscous glass forming glycerol and its nanocolloid based on Ag nanoparticles, as the function of temperature and pressure up to challenging P more than 1.5 GPa, are discussed. The analysis is focused on the fractional Debye-Stokes-Einstein relation FDSE sigma times tau to the power S equals const., where tau and sigma are for the structural relaxation time and electric conductivity are functions of T and P, respectively. For temperature tests in glycerol the clear evidence for the almost coupled exponent S equals 1 was obtained. For the supercooled nanocolloid the crossover to the decoupled domain associated with S equals 0.91 was noted. In super pressed glycerol and the nanocolloid the clear cross over from the domain described by the exponent S equals 1 to S less than 1 appeared on the GPa domain. For the nanocolloid it is associated with particularly strong decoupling, related to S equals 0.5, and occurs at well-defined pressure. This can suggest a possible fluid-fluid transition. Questions related to the validity of the Debye-Stokes tau equals approx. eta over T and Maxwell tau equals approx. eta relations, where eta is for viscosity, are also addressed. Results obtained do not support the recently suggested universality of the fractional exponent describing orientational and translational decoupling., Comment: 6 figures

Results solving the long standing puzzle regarding the phase diagram and the pressure evolution of the melting temperature Tm(P) of gallium nitride (GaN), the most promising semiconducting material for innovative modern electronic applications, are presented. The analysis is based on (i) studies of the decomposition curve in P-T plane up to challenging P equal 9 GPa, (ii) novel method enabling Tm(P) determination despite the earlier decomposition, and (iii) the pressure invariant parameterization of Tm(P) curve, showing the reversal melting for P greater-than 22 GPa. This is linked to a possible fluid-fluid crossover under extreme pressures and temperatures. The importance of results for the development of GaN based technologies is indicated.

Using the Landau-de Gennes theory, the temperature, pressure and frequency dependence of the non-linear effect in the isotropic phase above the isotropic-cholesteric phase transition is calculated. The influence of pressure on the isotropic-cholesteric phase transition is discussed by varying the coupling between the orientational order parameter and the macroscopic polarization of polar cholesterics. Comparing the results of the calculations with existing data, we finally conclude that the model provides a description of the isotropic-cholesteric transition that takes all experimentally known features of the unusual negative and positive pretransitional effect in the isotropic phase of the system into account in a qualitatively correct way.