Two-Dimensional Phase Transitions Associated with a Surface Miscibility Gap in Cu-Ag Alloys

1990 ◽  
Vol 202 ◽  
Author(s):  
Y. Liu ◽  
P. Wynblatt
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Critical Temperature ◽  
Abrupt Change ◽  
Surface Composition ◽  
Bulk Composition ◽  
Miscibility Gap ◽  
Experimental Measurements ◽  
Two Dimensional ◽  
Surface Phase

ABSTRACTA surface phase transition associated with a surface miscibility gap has been observed on the (111) surface of Cu-Ag alloys both in computer simulations and in experimental measurements of surface composition. This transition is characterized by an abrupt change in surface composition associated with changes in either bulk composition or temperature.The simulations have revealed that the transition from a Cu-rich to a Ag-rich surface phase is accompanied by interesting changes in surface structure. The experiments show that the surface critical temperature lies somewhere between 505 and 560°C.

scholarly journals Spherical model and quantum phase transitions

2021 ◽  
Vol 2094 (2) ◽  
pp. 022027
Author(s):  
V N Udodov
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Critical Temperature ◽  
Critical Exponents ◽  
Quantum Phase Transitions ◽  
Dimensional Space ◽  
Spherical Model ◽  
Quantum Phase ◽  
Two Dimensional ◽  
Epsilon Expansion

Abstract The spherical Berlin-Katz model is considered in the framework of the epsilon expansion in one-dimensional and two-dimensional space. For the two-dimensional and threedimensional cases in this model, an exact solution was previously obtained in the presence of a field, and for the two-dimensional case the critical temperature is zero, that is, a “quantum” phase transition is observed. On the other hand, the epsilon expansion of critical exponents with an arbitrary number of order parameter components is known. This approach is consistent with the scaling paradigm. Some critical exponents are found for the spherical model in one-and twodimensional space in accordance with the generalized scaling paradigm and the ideas of quantum phase transitions. A new formula is proposed for the critical heat capacity exponent, which depends on the dynamic index z, at a critical temperature equal to zero. An expression is proposed for the order of phase transition with a change in temperature (developing the approach of R. Baxter), which also depends on the z index. An interpolation formula is presented for the effective dimension of space, which is valid for both a positive critical temperature and a critical temperature equal to zero. This formula is general. Transitions with a change in the field in a spherical model at absolute zero are also considered.

QUANTUM PHASE TRANSITIONS AND ENTANGLEMENT IN J1–J2 MODEL

2004 ◽  
Vol 15 (08) ◽  
pp. 1095-1103 ◽  
Author(s):  
RECEP ERYIĞIT ◽  
RESUL ERYIĞIT ◽  
YIĞIT GÜNDÜÇ
Keyword(s):  
Phase Transition ◽  
Phase Diagram ◽  
Phase Transitions ◽  
Ground State ◽  
Abrupt Change ◽  
Quantum Phase Transitions ◽  
Nearest Neighbors ◽  
Competing Interactions ◽  
One Dimensional ◽  
Transition Points

We study ground state pairwise entanglement within one-dimensional spin-1/2 antiferromagnetic J1–J2 model with competing interactions. Contrary to some claims we found that frustration does not increase entanglement. Concurrence of nearest and next nearest neighbors are found to show abrupt change at phase transition points. We also show that the concurrence can be used to classify the phase diagram of the model in anisotropy–frustration plane.

Two Species/Nonideal Solution Model for Amorphous/Amorphous Phase Transitions

1996 ◽  
Vol 455 ◽  
Author(s):  
Cornelius T. Moynihan
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Critical Temperature ◽  
Amorphous Phase ◽  
Thermodynamic Model ◽  
Critical Pressure ◽  
Solution Model ◽  
Amorphous Phases ◽  
First Order ◽  
Temperature And Pressure

ABSTRACTA simple macroscopic thermodynamic model for first order transitions between two amorphous phases in a one component liquid is reviewed, augmented and evaluated. The model presumes the existence in the liquid of two species, whose concentrations are temperature and pressure dependent and which form a solution with large, positive deviations from ideality. Application of the model to recent data indicates that water can undergo an amorphous/amorphous phase transition below a critical temperature Tc of 217K and above a critical pressure Pc of 380 atm.

THE GROUNDSTATES AND PHASES OF THE TWO-DIMENSIONAL FULLY FRUSTRATED XY MODEL

2009 ◽  
Vol 23 (20n21) ◽  
pp. 3939-3950
Author(s):  
PETTER MINNHAGEN ◽  
SEBASTIAN BERNHARDSSON ◽  
BEOM JUN KIM
Keyword(s):  
Phase Transition ◽  
Phase Diagram ◽  
Phase Transitions ◽  
Xy Model ◽  
Two Dimensional ◽  
Spin Configuration ◽  
Multicritical Points ◽  
Symmetry Phase

The 2D Fully Frustrated XY(FFXY) class of models is shown to contain a new groundstate in addition to the checkerboard groundstate of the standard 2D XY model. The spin configuration of this additional groundstate is obtained and its connection to a broken Z2-symmetry explained. This means that the class of 2D FFXY models belongs within a U(1) ⊗ Z2 ⊗ Z2-symmetry phase-transition representation. The phase diagram is reviewed and the central charges of the four multicritical points described. The implications for the standard 2D FFXY-model are discussed and elucidated, in particular with respect to the long standing controversy concerning the phase transitions of the standard 2D FFXY-model.

scholarly journals Plastic Yielding as a Phase Transition

1999 ◽  
Vol 66 (2) ◽  
pp. 289-298 ◽  
Author(s):  
M. Ortiz
Keyword(s):  
Phase Transition ◽  
Shear Stress ◽  
Critical Temperature ◽  
Ising Model ◽  
Yield Point ◽  
Slip Plane ◽  
Dislocation Loop ◽  
Lattice Gas ◽  
Two Dimensional ◽  
Statistical Mechanical

A statistical mechanical theory of forest hardening is developed in which yielding arises as a phase transition. For simplicity, we consider the case of a single dislocation loop moving on a slip plane through randomly distributed forest dislocations, which we treat as point obstacles. The occurrence of slip at the sites occupied by these obstacles is assumed to require the expenditure of a certain amount of work commensurate with the strength of the obstacle. The case of obstacles of infinite strength is treated in detail. We show that the behavior of the dislocation loop as it sweeps the slip plane under the action of a resolved shear stress is identical to that of a lattice gas, or, equivalently, to that of the two-dimensional spin-1/2 Ising model. In particular, there exists a critical temperature Tc below which the system exhibits a yield point, i.e., the slip strain increases sharply when the applied resolved shear stress attains a critical value. Above the critical temperature the yield point disappears and the slip strain depends continuously on the applied stress. The critical exponents, which describe the behavior of the system near the critical temperature, coincide with those of the two-dimensional spin-1/2 Ising model.

scholarly journals Coupling between lipid miscibility and phosphotyrosine driven protein condensation at the membrane

2020 ◽  
Author(s):  
J. K. Chung ◽  
W. Y. C. Huang ◽  
C. B. Carbone ◽  
L. M. Nocka ◽  
A. N. Parikh ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Phase Separation ◽  
Membrane Surface ◽  
Adaptor Protein ◽  
Receptor Activation ◽  
Lipid Phase ◽  
Two Dimensional ◽  
Sos Protein ◽  
Lipid Phase Separation

AbstractLipid miscibility phase separation has long been considered to be a central element of cell membrane organization. More recently, protein condensation phase transitions, into three-dimensional droplets or in two-dimensional lattices on membrane surfaces, have emerged as another important organizational principle within cells. Here, we reconstitute the LAT:Grb2:SOS protein condensation on the surface of giant unilamellar vesicles capable of undergoing lipid phase separations. Our results indicate that assembly of the protein condensate on the membrane surface can drive lipid phase separation. This phase transition occurs isothermally and is governed by tyrosine phosphorylation on LAT. Furthermore, we observe that the induced lipid phase separation drives localization of the SOS substrate, K-Ras, into the LAT:Grb2:SOS protein condensate.Statement of SignificanceProtein condensation phase transitions are emerging as an important organizing principles in cells. One such condensate plays a key role in T cell receptor signaling. Immediately after receptor activation, multivalent phosphorylation of the adaptor protein LAT at the plasma membrane leads to networked assembly of a number of signaling proteins into a two-dimensional condensate on the membrane surface. In this study, we demonstrate that LAT condensates in reconstituted vesicles are sufficient to drive lipid phase separation. This lipid reorganization drives another key downstream signaling molecule, Ras, into the LAT condensates. These results show that the LAT condensation phase transition, which is actively controlled by phosphorylation reactions, extends its influence to control lipid phase separation in the underlying membrane.

scholarly journals Chiral phase transition in QED3 at finite temperature

2016 ◽  
Vol 31 (36) ◽  
pp. 1650198
Author(s):  
Pei-Lin Yin ◽  
Hai-Xiao Xiao ◽  
Wei Wei ◽  
Hong-Tao Feng ◽  
Hong-Shi Zong
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Critical Temperature ◽  
Finite Temperature ◽  
Chiral Symmetry Breaking ◽  
Chiral Condensate ◽  
The Other ◽  
Thermodynamic Quantities ◽  
Chiral Phase ◽  
Chiral Phase Transition

In the framework of Dyson–Schwinger equations, we employ two kinds of criteria (one kind is the chiral condensate, the other kind is thermodynamic quantities, such as the pressure, the entropy, and the specific heat) to investigate the nature of chiral phase transitions in QED3 for different fermion flavors. It is found that the chiral phase transitions in QED3 for different fermion flavors are all typical second-order phase transitions; the critical temperature and order of the chiral phase transition obtained from the chiral condensate and susceptibility are the same with that obtained by the thermodynamic quantities, which means that they are equivalent in describing the chiral phase transition; the critical temperature decreases as the number of fermion flavors increases and there is a boundary that separates the [Formula: see text] plane into chiral symmetry breaking and restoration regions.

Phase Transition in 2D Anisotropic Ising Model with Next-Nearest Neighbor Interactions in a Magnetic Field

SPIN ◽  
2018 ◽  
Vol 08 (03) ◽  
pp. 1850010
Author(s):  
D. Farsal ◽  
M. Badia ◽  
M. Bennai
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Phase Diagram ◽  
Monte Carlo ◽  
Magnetic Susceptibility ◽  
Critical Temperature ◽  
Ising Model ◽  
Nearest Neighbor ◽  
Two Dimensional ◽  
The Magnetic Field

The critical behavior at the phase transition of the ferromagnetic two-dimensional anisotropic Ising model with next-nearest neighbor (NNN) couplings in the presence of the field is determined using mainly Monte Carlo (MC) method. This method is used to investigate the phase diagram of the model and to verify the existence of a divergence at null temperature which often appears in two-dimensional systems. We analyze also the influence of the report of the NNN interactions [Formula: see text] and the magnetic field [Formula: see text] on the critical temperature of the system, and we show that the critical temperature depends on the magnetic field for positive values of the interaction. Finally, we have investigated other thermodynamical qualities such as the magnetic susceptibility [Formula: see text]. It has been shown that their thermal behavior depends qualitatively and quantitatively on the strength of NNN interactions and the magnetic field.

PHASE TRANSITIONS ON ALLOY SURFACES

1996 ◽  
Vol 03 (05n06) ◽  
pp. 1791-1809 ◽  
Author(s):  
Y. TERAOKA
Keyword(s):  
Phase Transitions ◽  
Transition Temperature ◽  
Binary Alloy ◽  
Surface Segregation ◽  
Lattice Gas ◽  
Two Dimensional ◽  
Surface Phase ◽  
Ordered Structures ◽  
Infinite Systems ◽  
Surface Phase Transitions

Various kinds of quasi-two-dimensional order-disorder phase transitions on binary alloy surfaces are discussed on the basis of the lattice gas model with appropriate approximations. The importance of surface segregation is pointed out in understanding phase transitions on alloy surfaces. Ordered structures localized on the surfaces are found above the bulk transition temperature, and a possibility of finding surface ordered structures with a different symmetry from the bulk ordered one is discussed, too. As for both ordering and segregating alloys, semi-infinite systems with surfaces are discussed above and below the bulk transition temperatures; in particular, the relation of the surface phase transitions to the bulk ones is focused on.

Notizen: Austausch von Nitrit- gegen Bromidanionen in Na3NO3 / Replacement of Nitrite by Bromide Anions in Na3NO3

1989 ◽  
Vol 44 (8) ◽  
pp. 996-998 ◽  
Author(s):  
M. Jansen ◽  
W. Müller
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Solid Solutions ◽  
Room Temperature ◽  
Mixed Crystals ◽  
Miscibility Gap ◽  
Temperature Range ◽  
Collective Interactions

Na3O(NO2) and Na3OBr are isostructural and form solid solutions with a miscibility gap χ = 0.28 to 0.62 as referred to Na3OBrx(NO2)1-x, at room temperature. Above 593 Κ formation of mixed crystals was observed for all compositions. In contrast to pure Na3O(NO2), the solid solutions do not undergo any phase transition in the investigated temperature range from 293 Κ to 130 K. These findings reveal that collective interactions between the dynamically disordered NO2--groups are involved in the phase transitions of Na3NO3.

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