Ultralow-fluence single-shot optical crystalline-to-amorphous phase transition in Ge–Sb–Te nanoparticles

Nanoscale ◽  
2018 ◽  
Vol 10 (35) ◽  
pp. 16574-16580 ◽  
Author(s):  
Barbara Casarin ◽  
Antonio Caretta ◽  
Bin Chen ◽  
Bart J. Kooi ◽  
Roberta Ciprian ◽  
...  
Keyword(s):  
Phase Transition ◽  
Laser Pulse ◽  
Phase Change ◽  
Amorphous Phase ◽  
Change Process ◽  
Single Laser Pulse ◽  
Single Shot ◽  
Single Laser ◽  
Phase Change Process

Ge2Sb2Te5 crystalline nanoparticles amorphize through a single laser pulse with exceptional low fluence, boosting the energetics of a phase-change process.

scholarly journals Effects of Surface Rotation on the Phase Change Process in a 3D Complex-Shaped Cylindrical Cavity with Ventilation Ports and Installed PCM Packed Bed System during Hybrid Nanofluid Convection

Mathematics ◽  
2021 ◽  
Vol 9 (20) ◽  
pp. 2566
Author(s):  
Lioua Kolsi ◽  
Fatih Selimefendigil ◽  
Mohamed Omri
Keyword(s):  
Phase Transition ◽  
Phase Change ◽  
Change Process ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Packed Bed ◽  
Reynolds Numbers ◽  
Hybrid Nanofluid ◽  
Surface Rotation ◽  
Phase Change Process

The combined effects of surface rotation and using binary nanoparticles on the phase change process in a 3D complex-shaped vented cavity with ventilation ports were studied during nanofluid convection. The geometry was a double T-shaped rotating vented cavity, while hybrid nanofluid contained binary Ag–MgO nano-sized particles. One of the novelties of the study wasthat a vented cavity was first used with the phase change–packed bed (PC–PB) system during nanofluid convection. The PC–PB system contained a spherical-shaped, encapsulated PCM paraffin wax. The Galerkin weighted residual finite element method was used as the solution method. The computations were carried out for varying values of the Reynolds numbers (100 ≤ Re ≤ 500),rotational Reynolds numbers (100 ≤ Rew ≤ 500), size of the ports (0.1L1 ≤ di ≤ 0.5L1), length of the PC–PB system (0.4L1 ≤ L0 ≤ L1), and location of the PC–PB (0 ≤ yp ≤ 0.25H). In the heat transfer fluid, the nanoparticle solid volume fraction amount was taken between 0 and 0.02%. When the fluid stream (Re) and surface rotational speed increased, the phase change process became fast. Effects of surface rotation became effective for lower values of Re while at Re = 100 and Re = 500; full phase transition time (tp) was reduced by about 39.8% and 24.5%. The port size and nanoparticle addition in the base fluid had positive impacts on the phase transition, while 34.8% reduction in tp was obtained at the largest port size, though this amount was only 9.5%, with the highest nanoparticle volume fraction. The length and vertical location of the PC–PB system have impacts on the phase transition dynamics. The reduction and increment amount in the value of tp with varying location and length of the PC–PB zone became 20% and 58%. As convection in cavities with ventilation ports are relevant in many thermal energy systems, the outcomes of this study will be helpful for the initial design and optimization of many PCM-embedded systems encountered in solar power, thermal management, refrigeration, and many other systems.

scholarly journals Combined Effects of Sequential Velocity and Variable Magnetic Field on the Phase Change Process in a 3D Cylinder Having a Conic-Shaped PCM-Packed Bed System

Mathematics ◽  
2021 ◽  
Vol 9 (23) ◽  
pp. 3019
Author(s):  
Lioua Kolsi ◽  
Fatih Selimefendigil ◽  
Mohamed Omri ◽  
Lotfi Ladhar
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Field Strength ◽  
Phase Change ◽  
Magnetic Field Strength ◽  
Change Process ◽  
Packed Bed ◽  
Variable Magnetic Field ◽  
Velocity Parameter ◽  
Phase Change Process

Effects of sequential velocity and variable magnetic field on the phase change during hybrid nanofluid convection through a 3D cylinder containing a phase-change material packed bed (PCM-PB) system is analyzed with the finite element method. As the heat transfer fluid, 40% ethylene glycol with hybrid TiO2-Al2O3 nanoparticles is considered. Impacts of the sequential velocity parameter (K, between 0.5 and 1.5), geometric factor of the conic-shaped PCM-PB (M, between 0.2 and 0.9), magnetic field strength (Ha number between 0 and 50) and solid volume fraction of hybrid nanoparticles (vol.% between 0.02% and 0.1%) on the phase change dynamics are explored. Effects of both constant and varying magnetic fields on the phase change process were considered. Due to the increased fluid velocity at the walls, the phase change becomes higher with higher values of the sequential velocity parameter (K). There is a 21.6% reduction in phase transition time (tF) between the smallest and highest values of K both in the absence and presence of a constant magnetic field. The value of tF is reduced with higher magnetic field strength and the amount of reduction depends upon the sequential velocity parameter. At K = 1.5, the reduction amount with the highest Ha number is 14.7%, while it is 26% at K = 0.5. When nanoparticle is loaded in the base fluid, the value of tF is further reduced. In the absence of a magnetic field, the amount of phase-transition time reduction is 6.9%, while at Ha = 50, it is 11.7%. The phase change process can be controlled with varying magnetic field parameters as well. As the wave number and amplitude of the varying magnetic field are considered, significant changes in the tF are observed.

Laser irradiation-induced modification of the amorphous phase in GeTe films: the role of intermediate Ge–Te bonding in the crystallization mechanism

2015 ◽  
Vol 3 (36) ◽  
pp. 9393-9402 ◽  
Author(s):  
Seung Jong Park ◽  
Hanjin Park ◽  
Moon Hyung Jang ◽  
Min Ahn ◽  
Won Jun Yang ◽  
...  
Keyword(s):  
Phase Change ◽  
Laser Irradiation ◽  
Amorphous Phase ◽  
Change Process ◽  
Crystallization Mechanism ◽  
Bonding Structure ◽  
Phase Change Process ◽  
Local Bonding

Modified amorphous GeTe was analyzed in terms of variations in the local bonding structure. Inducstion of intermediated Ge–Te bonding in modified structure critically affects the phase change process.

Single laser pulse compression via strongly coupled stimulated Brillouin scattering in plasma

2016 ◽  
Vol 23 (7) ◽  
pp. 073516 ◽  
Author(s):  
H. Peng ◽  
Z. H. Wu ◽  
Y. L. Zuo ◽  
Z. M. Zhang ◽  
K. N. Zhou ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Pulse Compression ◽  
Brillouin Scattering ◽  
Stimulated Brillouin Scattering ◽  
Single Laser Pulse ◽  
Strongly Coupled ◽  
Single Laser ◽  
Stimulated Brillouin

All-optical magnetic recording in garnets using a single laser pulse at L-band telecom wavelengths

2021 ◽  
Vol 118 (26) ◽  
pp. 262401
Author(s):  
Antoni Frej ◽  
Andrzej Maziewski ◽  
Andrzej Stupakiewicz
Keyword(s):  
Laser Pulse ◽  
Magnetic Recording ◽  
Single Laser Pulse ◽  
Single Laser ◽  
All Optical ◽  
L Band

scholarly journals Equation-of-state studies using a 10-Hz Nd:YAG laser oscillator

2003 ◽  
Vol 21 (4) ◽  
pp. 615-626 ◽  
Author(s):  
M. SHUKLA ◽  
A. UPADHYAY ◽  
V.K. SENECHA ◽  
P. KHARE ◽  
S. BANDYAOPADHYAY ◽  
...  
Keyword(s):  
Equation Of State ◽  
Laser Pulse ◽  
Beam Quality ◽  
Impedance Matching ◽  
Laser System ◽  
Control Unit ◽  
Aluminum Foil ◽  
Single Laser Pulse ◽  
High Contrast ◽  
Single Laser

A commercial mode locked cavity dumped Nd:YAG dye laser operating at 10 Hz repetition rate is modified to produce a high contrast (>5000:1) single laser pulse while maintaining the energy stability and high beam quality. A trigger generator biases the cavity dumping photodiode, which is triggered externally by a pulse from the microprocessor-based control unit controlling a ∼2 J/200 ps laser chain. In the laser chain, the high contrast (>5000:1) is achieved by an external pulse selector based on single Pockel's cell to select a single laser pulse of high contrast, which is a prerequisite for experimental study of the equation of state. Laser-induced shock velocity measurement in thin aluminum, gold on aluminum, and copper on aluminum foil targets using this modified laser system are also presented. The equation of state of Al, Au, and Cu obtained using an impedance matching technique are in agreement with the reported results of SESAME and simulation results.

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