OBSERVATION OF PHASE TRANSITIONS AT THE (100) SURFACE OF Al-3 at.% Ag

1995 ◽  
Vol 02 (02) ◽  
pp. 141-145 ◽  
Author(s):  
E. WETLI ◽  
M. HOCHSTRASSER ◽  
D. PESCIA ◽  
M. ERBUDAK
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Photoelectron Spectroscopy ◽  
Short Range ◽  
Short Range Order ◽  
Elevated Temperatures ◽  
X Ray ◽  
First Order ◽  
First Order Phase Transition ◽  
First Order Phase

In the bulk binary alloy Al-3 at.% Ag , Ag 2 Al precipitates are formed below 410°C which are reversibly dissolved at elevated temperatures. We have followed this phase transition at a (100) surface as a function of temperature by monitoring the bandwidth of the Ag 4d states in X-ray photoelectron spectroscopy. Since the bandwidth measures the coordination number of the emitting atoms, it directly reveals the short-range order of the Ag atoms at the surface. The measurements show that the dissolution of the Ag -rich clusters starts at temperatures at least 100 K below the bulk transition, and the observed hysteresis behavior is indicative of a first-order phase transition at the surface.

scholarly journals Break of symmetry at the surface of IrTe2 upon phase transition measured by X-ray photoelectron diffraction

2021 ◽  
Author(s):  
Maxime Rumo ◽  
Aki Pulkkinen ◽  
KeYuan Ma ◽  
Fabian von Rohr ◽  
Matthias Muntwiler ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Room Temperature ◽  
Local Environment ◽  
Atomic Position ◽  
X Ray ◽  
Photoelectron Diffraction ◽  
First Order ◽  
First Order Phase Transition ◽  
First Order Phase

Abstract IrTe2 undergoes a series of charge-ordered phase transitions below room temperature that are characterized by the formation of stripes of Ir dimers of different periodicities. Full hemispherical X-ray photoelectron diffraction (XPD) experiments have been performed to investigate the atomic position changes undergone near the surface of 1T−IrTe2 in the first-order phase transition, from the (1 × 1) phase to the (5 × 1) phase. Comparison between experiment and simulation allows us to identify the consequence of the dimerization on the Ir atoms local environment. We report that XPD permits to unveil the break of symmetry of IrTe2 trigonal to a monoclonic unit cell and confirm the occurence of the (5 × 1) reconstruction within the first few layers below the surface with a staircase-like stacking of dimers.

GRAVITATIONAL WAVES FROM COSMOLOGICAL PHASE TRANSITIONS

2009 ◽  
Vol 24 (08n09) ◽  
pp. 1541-1544
Author(s):  
ARIEL MÉGEVAND
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Gravitational Waves ◽  
Order Phase Transition ◽  
Gravitational Radiation ◽  
First Order ◽  
First Order Phase Transition ◽  
First Order Phase

I discuss the gravitational radiation produced in a first-order phase transition due to the turbulence that is caused by bubble expansion. I compare the cases of deflagration and detonation bubbles.

Phase transitions and topological defects

2018 ◽  
Author(s):  
Michael Kachelriess
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Early Universe ◽  
Topological Defects ◽  
False Vacuum ◽  
First Order ◽  
Broken Symmetries ◽  
First Order Phase Transition ◽  
True Vacuum ◽  
First Order Phase

As the early universe cools down, it may perform transitions to phases with more and more broken symmetries. In a first-order phase transition, fields may be trapped in the false vacuum; the rate of the resulting tunneling process to the true vacuum is derived. Phase transitions can lead also to the formation of topological defects. Their structure and the reason for their stability are discussed.

Modeling of Phase Transitions Kinetics in Systems with Two Interacting Order Parameters

2016 ◽  
Vol 845 ◽  
pp. 166-169 ◽  
Author(s):  
Dmitry A. Kuzmin ◽  
Igor V. Bychkov ◽  
Ivan Yu. Biryukov ◽  
Alexander P. Kamantsev ◽  
Victor V. Koledov ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Order Phase Transition ◽  
Transition Process ◽  
Order Parameters ◽  
First Order ◽  
First Order Phase Transition ◽  
1D Model ◽  
Coupled Solution ◽  
First Order Phase

We present common 1D model of first order phase transition based on coupled solution of order parameters evolution and heat transfer equations. Such a model may be used for simulation of phase transitions in multiferroics or magnetostructural phase transitions, for example. First order phase transition process has been described by Landau-Khalatnikov-like equation with the thermodynamic potential of 2-3-4 and 2-4-6 types.

WEIGHT RATIO FIXING AT FIRST ORDER PHASE TRANSITIONS

1992 ◽  
Vol 03 (05) ◽  
pp. 1109-1117
Author(s):  
THOMAS LIPPERT ◽  
KLAUS SCHILLING ◽  
PEER UEBERHOLZ ◽  
GYAN BHANOT
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Weight Ratio ◽  
Phenomenological Method ◽  
Reliable Determination ◽  
First Order ◽  
First Order Phase Transition ◽  
Two Phases ◽  
First Order Phase

The presence of strong metastabilities in computer simulations of models showing a first order phase transition hinders a reliable determination of the weight ratio between the two phases. We discuss a new phenomenological method which allows an accurate fixing of the weight ratio using the standard multihistogram procedure.

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