scholarly journals Second-order structural phase transitions, free energy curvature, and temperature-dependent anharmonic phonons in the self-consistent harmonic approximation: Theory and stochastic implementation

2017 ◽  
Vol 96 (1) ◽  
Author(s):  
Raffaello Bianco ◽  
Ion Errea ◽  
Lorenzo Paulatto ◽  
Matteo Calandra ◽  
Francesco Mauri
Keyword(s):  
Free Energy ◽  
Phase Transitions ◽  
Approximation Theory ◽  
Structural Phase ◽  
Harmonic Approximation ◽  
Second Order ◽  
The Self ◽  
Structural Phase Transitions ◽  
Temperature Dependent ◽  
Self Consistent

Temperature-induced structural phase transitions in RERhSn (RE = Y, Gd-Tm, Lu)

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Simon Engelbert ◽  
Rolf-Dieter Hoffmann ◽  
Jutta Kösters ◽  
Steffen Klenner ◽  
Rainer Pöttgen
Keyword(s):  
Rare Earth ◽  
Phase Transitions ◽  
Driving Force ◽  
Room Temperature ◽  
Structural Phase ◽  
Structural Phase Transitions ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray

Abstract The structures of the equiatomic stannides RERhSn with the smaller rare earth elements Y, Gd-Tm and Lu were reinvestigated on the basis of temperature-dependent single crystal X-ray diffraction data. GdRhSn crystallizes with the aristotype ZrNiAl at 293 and 90 K. For RE = Y, Tb, Ho and Er the HP-CeRuSn type (approximant with space group R3m) is already formed at room temperature, while DyRhSn adopts the HP-CeRuSn type below 280 K. TmRhSn and LuRhSn show incommensurate modulated variants with superspace groups P31m(1/3; 1/3; γ) 000 (No. 157.1.23.1) (γ = 3/8 for TmRhSn and γ = 2/5 for LuRhSn). The driving force for superstructure formation (modulation) is a strengthening of Rh–Sn bonding. The modulation is expressed in a 119Sn Mössbauer spectrum of DyRhSn at 78 K through line broadening.

scholarly journals Temperature-dependent phase evolution of copper-oxide thin-films on Au(111)

2018 ◽  
Vol 20 (8) ◽  
pp. 5636-5643 ◽  
Author(s):  
Christoph Möller ◽  
Hanna Fedderwitz ◽  
Claudine Noguera ◽  
Jacek Goniakowski ◽  
Niklas Nilius
Keyword(s):  
Thin Films ◽  
Phase Transitions ◽  
Dft Calculations ◽  
Copper Oxide ◽  
Structural Phase ◽  
Oxide Films ◽  
Phase Evolution ◽  
Structural Phase Transitions ◽  
Oxide Thin Films ◽  
Temperature Dependent

STM and DFT calculations are employed to explore structural phase transitions in thin copper-oxide films grown on Au(111).

scholarly journals Observing a previously hidden structural-phase transition onset through heteroepitaxial cap response

2019 ◽  
Vol 116 (10) ◽  
pp. 4141-4146 ◽  
Author(s):  
Fanli Lan ◽  
Hongyan Chen ◽  
Hanxuan Lin ◽  
Yu Bai ◽  
Yang Yu ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
Second Order ◽  
Structural Phase Transitions ◽  
Lsmo Film ◽  
Precursor Phase ◽  
Micrometer Scale ◽  
Atomically Flat

Characterization of the onset of a phase transition is often challenging due to the fluctuations of the correlation length scales of the order parameters. This is especially true for second-order structural-phase transition due to minute changes involved in the relevant lattice constants. A classic example is the cubic-to-tetragonal second-order phase transition in SrTiO3(STO), which is so subtle that it is still unresolved. Here, we demonstrate an approach to resolve this issue by epitaxially grown rhombohedral La0.7Sr0.3MnO3(LSMO) thin films on the cubic STO (100) substrate. The shear strain induced nanotwinning waves in the LSMO film are extremely sensitive to the cubic-to-tetragonal structural-phase transitions of the STO substrate. Upon cooling from room temperature, the development of the nanotwinning waves is spatially inhomogeneous. Untwinned, atomically flat domains, ranging in size from 100 to 300 nm, start to appear randomly in the twinned phase between 265 and 175 K. At ∼139 K, the untwinned, atomically flat domains start to grow rapidly into micrometer scale and finally become dominant at ∼108 K. These results indicate that the low-temperature tetragonal precursor phase of STO has already nucleated at 265 K, significantly higher than the critical temperature of STO (∼105 K). Our work paves a pathway to visualize the onset stages of structural-phase transitions that are too subtle to be observed using direct-imaging methods.

STRUCTURAL PHASE TRANSITIONS IN A DISCRETE ONE-DIMENSIONAL CHAIN

2009 ◽  
Vol 01 (03) ◽  
pp. 545-556 ◽  
Author(s):  
SRIKANTH VEDANTAM ◽  
S. MOHANRAJ
Keyword(s):  
Phase Transitions ◽  
Interatomic Potential ◽  
Structural Phase ◽  
Structural Phase Transitions ◽  
Temperature Dependent ◽  
One Dimensional ◽  
Nearest Neighbours ◽  
Two Phases ◽  
A Chain ◽  
Exchange Of Stability

We present a lattice dynamics model for describing structural phase transitions in a one-dimensional setting. The model comprises of a chain of discrete masses interacting with nearest neighbours. In order to drive a temperature dependent exchange of stability between two phases, we allow the interatomic potential to be dependent on the temperature. The system exhibits thermal phase transitions accompanied by latent heat.

Structural phase transitions in YPtGe2 and GdPtGe2

2018 ◽  
Vol 47 (17) ◽  
pp. 6075-6088 ◽  
Author(s):  
Oliver Janka ◽  
Rolf-Dieter Hoffmann ◽  
Birgit Heying ◽  
Rainer Pöttgen
Keyword(s):  
Phase Transitions ◽  
Single Crystal ◽  
Diffraction Data ◽  
Structural Phase ◽  
Structural Phase Transitions ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Arc Melting

The germanides YPtGe2 and GdPtGe2 were synthesized from REGe2 precursor compounds and platinum by arc-melting and their structures were studied on the basis of temperature-dependent single crystal X-ray diffraction data.

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