Phase Diagram of Laser Induced Melt Morphologies On Silicon

1985 ◽  
Vol 51 ◽  
Author(s):  
John S. Preston ◽  
John E. Sipe ◽  
Henry M. Van Driel
Keyword(s):  
Phase Diagram ◽  
Steady State ◽  
Order Parameter ◽  
Large Range ◽  
Laser Intensity ◽  
Spot Size ◽  
Coexistence Region ◽  
Cw Laser ◽  
Experimental Parameters ◽  
Amorphous Structures

ABSTRACTDuring cw laser induced melting, over a large range of intensities, silicon films phase separate into patterns of coexisting solid and molten regions. We have identified several distinct and reproduceable morphologies of this inhomogeneous coexistence region ranging from random lamellae (“amorphous”) structures to periodically ordered (“crystalline”) strips. The type of morphology formed is a function of laser intensity and spot size and these parameters can be viewed as constituting the two axes for a steady state “phase diagram” of the structures. “Phase transitions” between these structures occur for small changes of the experimental parameters with the fraction of liquid being an order parameter.

Strongly Superlinear Light Emission and Large Induced Absorption in Oxidized Porous Silicon Films

1998 ◽  
Vol 536 ◽  
Author(s):  
H. Koyama ◽  
P. M. Fauchet
Keyword(s):  
Porous Silicon ◽  
Thermal Effects ◽  
Light Emission ◽  
Laser Intensity ◽  
Excitation Intensity ◽  
Silicon Films ◽  
Free Standing ◽  
Induced Absorption ◽  
Cw Laser ◽  
Oxidized Porous Silicon

AbstractThe optical properties of oxidized free-standing porous silicon films excited by a cw laser have been investigated. It is found that samples oxidized at 800–950 °C show a strongly superlinear light emission at an excitation intensity of ∼10 W/cm2. This emission has a peak at 900–1100 nm and shows a blueshift as the oxidation temperature is increased. These samples also show a very large induced absorption, where the transmittance is found to decrease reversibly by ≤99.7 %.The induced absorption increases linearly with increasing pump laser intensity. Both the superlinear emission and the large induced absorption are quenched when the samples are attached to materials with a higher thermal conductivity, suggesting that laser-induced thermal effects are responsible for these phenomena.

scholarly journals Bicritical Central Point of Ising Model Phase Diagram

2010 ◽  
Vol 2010 ◽  
pp. 1-5 ◽  
Author(s):  
Yahia Boughaleb ◽  
Mohammed Nouredine ◽  
Mohamed Snina ◽  
Rachid Nassif ◽  
Mohamed Bennai
Keyword(s):  
Phase Diagram ◽  
Order Parameter ◽  
Present Model ◽  
Central Point ◽  
Square Lattice ◽  
Ordered Structures ◽  
Ordered Phases ◽  
Algebraic Order ◽  
Pure Phases ◽  
Model Phase

We deal with a 2D half occupied square lattice with repulsive interactions between first and second neighboring particles. Despite the intensive studies of the present model the central point of the phase diagram for which the ratio of the two interaction strengths is still open. In the present paper we show, using standard Monte Carlo calculations, that the situation corresponds to a phase of mixed ordered structures quantified by an “algebraic” order parameter defined as the sum of densities of the existing ordered clusters. The introduced grandeur also characterizes the transitions towards the known pure ordered phases for the other values of as mentioned by the agreement of our results with those of the literature. The computation of the Cowley short range order parameter against suggests that the central point is bicritical and is a state to cross when passing between the two pure phases.

Effect of Experimental Parameters on Passivation Phenomena of Ti6Al4V Alloy in Acid Solution

2016 ◽  
Vol 710 ◽  
pp. 204-209
Author(s):  
Elamine Nouicer ◽  
Fatima Zohra Benlahreche ◽  
Abdelmadjid Nouicer
Keyword(s):  
Oxide Film ◽  
Acid Solution ◽  
Corrosion Potential ◽  
Large Range ◽  
Electrochemical Impedance ◽  
Ti6al4v Alloy ◽  
Paper Study ◽  
Transfer Resistance ◽  
Experimental Parameters ◽  
Increasing Trend

This paper study the effect of scan rates and imposed potential on the growth of the oxide film on the Ti6Al4V alloy surface in acid solution .Polarization curves, plotted at different scan rates show a large range of passivation, with no occurrence of transpassivation . It was found that the scan rate have not a significant effect on the passivation phenomenon. However, it influences the corrosion potential and the current density. Electrochemical impedance spectroscopy results show that the system behaviour is purely capacitive. The increasing trend in transfer resistance, film thickness and the exponent n with the imposed potential is due to the growth of a passive and compact oxide film.

A MEAN FIELD STUDY OF THE PHASE TRANSITIONS IN A CLASS OF SYSTEMS WITH COMPLEX ORDER PARAMETERS

1994 ◽  
Vol 08 (28) ◽  
pp. 3963-3986
Author(s):  
EVGENIA J. BLAGOEVA
Keyword(s):  
Phase Diagram ◽  
Phase Transitions ◽  
Order Parameter ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Unconventional Superconductors ◽  
Complex Order ◽  
The Mean ◽  
Expansion Coefficients

A generalized Landau free energy for a complex order parameter expanded up to sixth-order is investigated using group theoretical arguments and the mean-field approximation. Results for the phase transitions that occur are presented. The phase diagram for all allowed values of the expansion coefficients is constructed with an emphasis placed on the influence of the anisotropy in the order parameter space. The results can be used in discussions of unconventional superconductors and modulated structural and magnetic orderings.

scholarly journals Cluster Mean-Field Approach to the Steady-State Phase Diagram of Dissipative Spin Systems

2016 ◽  
Vol 6 (3) ◽  
Author(s):  
Jiasen Jin ◽  
Alberto Biella ◽  
Oscar Viyuela ◽  
Leonardo Mazza ◽  
Jonathan Keeling ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Steady State ◽  
Mean Field ◽  
Spin Systems ◽  
Field Approach

Calculation of steady-state dynamical phase diagram in U-Mo binary system under irradiation

2021 ◽  
Vol 544 ◽  
pp. 152698
Author(s):  
Yong Lu ◽  
Zheng Jiang ◽  
Linyang Li ◽  
Cuiping Wang ◽  
Xingjun Liu
Keyword(s):  
Phase Diagram ◽  
Steady State ◽  
Binary System ◽  
Dynamical Phase

Steady-State Dynamic Phase Diagram Calculation of U-Ti and U-V Binary System under Irradiation

2020 ◽  
Vol 993 ◽  
pp. 996-1003
Author(s):  
Yong Lu ◽  
Zheng Jiang ◽  
Qiao Qiao Tang ◽  
Cui Ping Wang ◽  
Xing Jun Liu
Keyword(s):  
Phase Diagram ◽  
Steady State ◽  
Binary System ◽  
Low Temperature ◽  
Equilibrium Phase ◽  
Equilibrium Phase Diagram ◽  
Enhanced Diffusion ◽  
Dynamical Phase ◽  
Irradiation Intensity ◽  
Phase Relationships

In this paper, by considering the irradiation-enhanced diffusion, a combination of effective free energy model and the thermodynamic model was used for studying the phase relationships in the U-Ti and U-V binary system under irradiation. The steady-state dynamical phase diagrams of U-Ti and U-V binary alloys under different irradiation intensities were calculated and compared with the conventional thermodynamic equilibrium phase diagram. The calculated results show that under irradiation the high-temperature stable (βTi, γU) and (γU,V) phases were stabilized at relatively low temperature resulting in invariant reactions at relatively low temperature. In addition, with the increase of the irradiation intensity, the temperature of the invariant reactions increased, and the phase regions of the (βTi, γU) and (γU,V) also increased.

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