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.

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 127I NQR and Crystal Structure Studies of [N(CH3)4]2 CdI4

2000 ◽  
Vol 55 (1-2) ◽  
pp. 225-229 ◽  
Author(s):  
Hideta Ishihara ◽  
Keizo Horiuchi ◽  
Thorsten M. Gesing ◽  
Shi-qi Dou ◽  
J.-Christian Buhl ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Order Phase Transition ◽  
Intensity Ratio ◽  
Room Temperature ◽  
Liquid Nitrogen Temperature ◽  
Temperature Phase ◽  
First Order ◽  
First Order Phase Transition ◽  
First Order Phase

The temperature dependence of 127I NQR and DSC as well as the crystal structure at room temperature of the title compound were determined. This compound shows a first-order phase transition of an order-disorder type at 245 K. Eight 127I(v1:m = ±1/2 ↔ ±3/2) NQR lines of 79.57, 81.86, 82.56, 83.36, 84.68, 87.72, 88.34, and 88.86 MHz, and corresponding eight 127I(v2: m = ±3/2 ↔±5/2) NQR lines were observed at liquid nitrogen temperature. Three 127I(υi) NQR lines wfth an intensity ratio of 1:1:2 in the order of decreasing frequency were observed just above the transition point and two NQR lines except for the middle-frequency line disappeared around room temperature. This temperature behavior of NQR lines is very similar to that observed in [N(CH3)4]2Hgl4. Another first-order phase transition takes place at 527 K. The structure of the room-temperature phase was redetermined: orthorhombic, Pnma, Z = 4, a = 1342.8(3), b = 975.7(2), c = 1696.5(3) pm. The NQR result of three lines with an intensity ratio of 1:1:2 is in agreement with this structure. The thermal displacement parameters of atoms in both cations and anions are large.

scholarly journals N-Methylpyrrolidinium hydrogen tartrate (NMPHT): an above-room-temperature order–disorder molecular switchable dielectric material

RSC Advances ◽  
2017 ◽  
Vol 7 (39) ◽  
pp. 24368-24373 ◽  
Author(s):  
Aurang Zeb ◽  
Tariq Khan ◽  
Muhammad Adnan Asghar ◽  
Zhihua Sun ◽  
Zhenyue Wu ◽  
...  
Keyword(s):  
Phase Transition ◽  
Order Phase Transition ◽  
Room Temperature ◽  
Dielectric Material ◽  
First Order ◽  
First Order Phase Transition ◽  
First Order Phase

A new above-room-temperature molecular switchable dielectric material, which undergoes a first-order phase transition induced by the order-disorder transformation of cation, has been reported.

Room-Temperature First-Order Phase Transition in a Charge-Disproportionated Molecular Conductor (MeEDO-TTF)2PF6

2008 ◽  
Vol 20 (24) ◽  
pp. 7551-7562 ◽  
Author(s):  
Xiangfeng Shao ◽  
Yoshiaki Nakano ◽  
Masafumi Sakata ◽  
Hideki Yamochi ◽  
Yukihiro Yoshida ◽  
...  
Keyword(s):  
Phase Transition ◽  
Order Phase Transition ◽  
Room Temperature ◽  
First Order ◽  
Molecular Conductor ◽  
First Order Phase Transition ◽  
A Charge ◽  
First Order Phase

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.

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