ROUGHNESS INFLUENCE ON SURFACE MELTING

2001 ◽  
Vol 08 (06) ◽  
pp. 599-608 ◽  
Author(s):  
FRAY DE LANDA CASTILLO ALVARADO ◽  
MARGARITO CRUZ PINEDA ◽  
JERZY H. RUTKOWSKI ◽  
LESZEK WOJTCZAK
Keyword(s):  
Field Theory ◽  
Phase Transition ◽  
Phase Diagram ◽  
Order Parameter ◽  
Surface Melting ◽  
Density Fluctuations ◽  
Solid Model ◽  
Van Der Waals Equation ◽  
Liquid Phases ◽  
Two Phases

The influence of surface roughness on surface melting phase transition is discussed within the molecular field theory. The roughness is characterized by the surface order parameter averaged over all the density fluctuations whose description corresponds to the discrete Gaussian solid-on-solid model. The potential governing the transition between the rough surface and the surface melting is considered in terms of the modified van der Waals equation of state. Its effective shape represents two intersecting parabolas with nonequal curvatures for the solid and liquid phases. The phase diagram shows the coexistence of two phases with rough and wet surfaces.

scholarly journals Toward precision cosmochronology

2020 ◽  
Vol 640 ◽  
pp. L11 ◽  
Author(s):  
Simon Blouin ◽  
Jérôme Daligault ◽  
Didier Saumon ◽  
Antoine Bédard ◽  
Pierre Brassard
Keyword(s):  
Phase Transition ◽  
Phase Diagram ◽  
Latent Heat ◽  
White Dwarf ◽  
Gravitational Energy ◽  
Physical Mechanisms ◽  
Slowing Down ◽  
Liquid Phases ◽  
Pile Up ◽  
O Phase

The continuous cooling of a white dwarf is punctuated by events that affect its cooling rate. The most significant of these events is the crystallization of its core, a phase transition that occurs once the C/O interior has cooled down below a critical temperature. This transition releases latent heat, as well as gravitational energy due to the redistribution of the C and O ions during solidification, thereby slowing down the evolution of the white dwarf. The unambiguous observational signature of core crystallization–a pile-up of objects in the cooling sequence–was recently reported. However, existing evolution models struggle to quantitatively reproduce this signature, casting doubt on their accuracy when used to measure the ages of stellar populations. The timing and amount of the energy released during crystallization depend on the exact form of the C/O phase diagram. Using the advanced Gibbs–Duhem integration method and state-of-the-art Monte Carlo simulations of the solid and liquid phases, we obtained a very accurate version of this phase diagram that allows a precise modeling of the phase transition. Despite this improvement, the magnitude of the crystallization pile-up remains underestimated by current evolution models. We conclude that latent heat release and O sedimentation alone are not sufficient to explain the observations, and that other unaccounted physical mechanisms, possibly 22Ne phase separation, play an important role.

scholarly journals Phase Transition of Ice at High Pressures and Low Temperatures

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 486
Author(s):  
Jinjin Xu ◽  
Jinfeng Liu ◽  
Jinyun Liu ◽  
Wenxin Hu ◽  
Xiao He ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Diagram ◽  
High Pressures ◽  
Structural Phase ◽  
Extreme Conditions ◽  
Dispersion Interactions ◽  
Many Body ◽  
Two Phases ◽  
Moller Plesset ◽  
The Many

The behavior of ice under extreme conditions undergoes the change of intermolecular binding patterns and leads to the structural phase transitions, which are needed for modeling the convection and internal structure of the giant planets and moons of the solar system as well as H2O-rich exoplanets. Such extreme conditions limit the structural explorations in laboratory but open a door for the theoretical study. The ice phases IX and XIII are located in the high pressure and low temperature region of the phase diagram. However, to the best of our knowledge, the phase transition boundary between these two phases is still not clear. In this work, based on the second-order Møller–Plesset perturbation (MP2) theory, we theoretically investigate the ice phases IX and XIII and predict their structures, vibrational spectra and Gibbs free energies at various extreme conditions, and for the first time confirm that the phase transition from ice IX to XIII can occur around 0.30 GPa and 154 K. The proposed work, taking into account the many-body electrostatic effect and the dispersion interactions from the first principles, opens up the possibility of completing the ice phase diagram and provides an efficient method to explore new phases of molecular crystals.

Modelling of Phase Diagram Boundaries at Equilibrium of Two Binary Regular Phases

1995 ◽  
Vol 60 (6) ◽  
pp. 911-916
Author(s):  
Jan Vřešťál ◽  
Ivo Stloukal
Keyword(s):  
Phase Diagram ◽  
Linear Function ◽  
Regular Solution ◽  
Gibbs Function ◽  
Temperature Dependent ◽  
Regular Solutions ◽  
Liquid Phases ◽  
Simplifying Assumptions ◽  
Two Phases ◽  
Solution Parameter

The conditions of occurrence of extremes on the solidus and liquidus curves in a binary isobaric phase diagram are specified. The solid and liquid phases are regarded as regular solutions in equilibrium. Two simplifying assumptions are made: (i) the Gibbs function of melting of the pure components is a linear function of temperature; (ii) the two phases in equilibrium are regular solutions with a temperature-dependent regular solution parameter. The conditions of occurrence of inflexion points on the solidus and/or liquidus curves are obtained by modelling.

scholarly journals TIME REVERSAL BREAKING SUPERCONDUCTING STATE IN THE PHASE DIAGRAM OF THE CUPRATES

2003 ◽  
Vol 17 (04n06) ◽  
pp. 614-620 ◽  
Author(s):  
G. SANGIOVANNI ◽  
M. CAPONE ◽  
S. CAPRARA
Keyword(s):  
Phase Transition ◽  
Phase Diagram ◽  
Order Phase Transition ◽  
Superconducting State ◽  
Time Reversal ◽  
Low Temperatures ◽  
Order Parameter ◽  
Andreev Reflection ◽  
Previous Analysis ◽  
Second Order Phase Transition

We review and extend a previous study1 on the symmetry of the superconducting state, stimulated by recent tunneling and Andreev reflection measurements giving robust evidences for the existence of a dx2-y2 + idxy order parameter in the overdoped regime of two different cuprates. Looking for a possible second-order phase transition from a standard dx2-y2 to a mixed and time reversal breaking state, we confirm the results of our previous analysis on La 2-x Sr x CuO 4. In the case of Y 1-y Ca y Ba 2 Cu 3 O 7-x as well, among all the allowed symmetries, the dx2 - y2 + idxy is the most favored one and the unconventional state is likely to occur in a small dome of the phase diagram located in the optimal-overdoped region and at very low temperatures.

scholarly journals Двумерные O(n)-модели с дефектами типа "случайная локальная анизотропия"

2020 ◽  
Vol 62 (4) ◽  
pp. 610
Author(s):  
А.А. Берзин ◽  
А.И. Морозов ◽  
А.С. Сигов
Keyword(s):  
Phase Transition ◽  
Phase Diagram ◽  
Order Parameter ◽  
Easy Axis ◽  
Critical Value ◽  
Smooth Transition ◽  
Two Dimensional ◽  
Continuous Symmetry ◽  
Local Anisotropy ◽  
Ordered State

The phase diagram of two-dimensional systems with continuous symmetry of the vector order parameter containing defects of the “random local anisotropy” type is investigated. In the case of a weakly anisotropic distribution of the easy anisotropy axes in the space of the order parameter, with decreasing temperature, a smooth transition takes place from the paramagnetic phase with dynamic fluctuations of the order parameter to the Imri-Ma phase with its static fluctuations. In the case when the anisotropic distribution of the easy axes induces a global anisotropy of the “easy axis” type that exceeds a critical value, the system goes into the Ising class of universality, and a phase transition to the ordered state occurs in it at a finite temperature.

scholarly journals The chiral and deconfinement phase transitions

Open Physics ◽  
2012 ◽  
Vol 10 (6) ◽  
Author(s):  
Fukun Xu ◽  
Mei Huang
Keyword(s):  
Phase Transition ◽  
Phase Diagram ◽  
Phase Transitions ◽  
Order Parameter ◽  
Gluon Condensate ◽  
Magnetic Confinement ◽  
Chiral Condensate ◽  
Qcd Phase Diagram ◽  
Dimension 2 ◽  
Deconfinement Phase Transition

AbstractBy introducing the dressed Polayakov loop or dual chiral condensate as a candidate order parameter to describe the deconfinement phase transition for light flavors, we discuss the interplay between the chiral and deconfinement phase transitions, and propose the possible QCD phase diagram at finite temperature and density. We also introduce a dynamical gluodynamic model with dimension-2 gluon condensate, which can describe the color electric deconfinement as well as the color magnetic confinement.

Rhombohedral and Monoclinic Phases of PZT near the Antiferroelectric and the Morphotropic Boundaries

2012 ◽  
Vol 184 ◽  
pp. 333-338 ◽  
Author(s):  
Francesco Cordero ◽  
Francesco Trequattrini ◽  
Floriana Craciun ◽  
Carmen Galassi
Keyword(s):  
Phase Transition ◽  
Phase Diagram ◽  
Curie Temperature ◽  
Structural Studies ◽  
M Phase ◽  
Frequency Independent ◽  
The Common ◽  
Two Phases ◽  
New Phase ◽  
Large Frequency

Anelastic and dielectric spectroscopy measurements are presented, which, together with previous measurements [1], clarify some controversial aspects of the phase diagram of PbZr1xTixO3close to the border with the antiferroelectric (AFE) phase, and at the morphotropic phase boundary (MPB). No evidence is found of a border separating monoclinic (M) from rhombohedral (R) phases, supporting recent structural studies according to which the two phases coexist, with the fraction of M prevailing near the MPB. A large frequency independent softening at the MPB indicates a genuine M phase over only finely twinned R phase. A new phase transition is found in both the anelastic and dielectric spectra atx= 0.1, at a temperatureTITbetween the Curie temperatureTCand the boundaryTTto the phases with tilted octahedra. Such a diffuse transition is interpreted as onset of disordered tilts, which finally become ordered belowTT. In this manner, the phase diagram of PZT is rationalised with respect to the common tendency of perovskites to undergo tilting when the mismatch between the cation sizes exceeds a threshold.

MAGNETIC PROPERTIES OF PSEUDO-BINARY Mn1−xFexSn2 ALLOYS

1993 ◽  
Vol 07 (01n03) ◽  
pp. 867-870 ◽  
Author(s):  
H. SHIRAISHI ◽  
T. HORI ◽  
Y. YAMAGUCHI ◽  
S. FUNAHASHI ◽  
K. KANEMATSU
Keyword(s):  
Field Theory ◽  
Phase Diagram ◽  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
High Temperature ◽  
Magnetic Structure ◽  
Magnetic Phase ◽  
Magnetic Phase Diagram ◽  
Molecular Field ◽  
Magnetic Phases

The magnetic susceptibility measurements have been made on antiferromagnetic compounds Mn1–xFexSn2 and the magnetic phase diagram was illustrated. The high temperature magnetic phases I and III, major phases, were analyzed on the basis of molecular field theory and explained the change of magnetic structure I⇌III occured at x≈0.8.

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