Laser-heated pedestal growth

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Nucleation and crystal growth underpin the formation of ordered structures from disordered systems, yet spontaneous nucleation is inherently stochastic and difficult to control. Seeding can introduce preformed nuclei to guide assembly, which offers a strategy to regulate these processes. Here, we investigate seeded nucleation in the two‐dimensional assembly of trimeric macromolecules using programable DNA tiles as a model system. Introducing a single DNA tile as a nucleation seed enabled size‐ and shape‐con

Laser Powder Bed Fusion (LPBF) is a promising metal additive manufacturing (AM) technology that enables high-precision fabrication of high-performance parts with unprecedented design flexibility. However, its widespread adoption remains hindered by the occurrence of various defects, which significantly degrade the mechanical properties and reproducibility of fabricated parts. These defects are inherently linked to the complex and dynamic nature of melt pool behavior, governed by a combination of laser-mater

L to H transition studies at JET have revealed an n = 0, m = 1 magnetic oscillation starting immediately at the L to H transition (called M-mode for brevity). While the magnetic oscillation is present a weak ELM-less H-mode regime is obtained, with a clear ...

In order to achieve high-efficiency perovskite solar cells, understanding both the crystal structure and the optoelectronic properties of perovskite layers is of importance. This paper uses crystallization analysis and the modeling study of two different p ...

Modeling of the kinetics of the synthesis process for calcium sulfate alpha-hemihydrate from gypsum formed by flue gas desulfurization (FGD) is important to produce high-performance products with minimal costs and production cycles under hydrothermal condi ...

We report the atmospheric pressure chemical vapour deposition (APCVD) of a dual layer transparent conductive oxide (TCO). This combines a fluorine doped tin oxide (FTO) base layer with a fluorine doped zinc oxide (FZO) top layer, where we seek to utilise t ...

Experimental studies of the novel snowflake divertor concept (D. Ryutov, Phys. Plasmas 14 (2007) 064502) performed in the NSTX and TCV tokamaks are reviewed in this paper. The snowflake divertor enables power sharing between divertor strike points, as well ...

This project deals with aspects involved in the growth of single-crystals of Constantan. Constantan is an alloy of Nickel in Copper, whose technological interest is that resistance is independent of temperature over a very large range of temperatures (hence the name Constantan). This, along with other suitable properties such as high strain sensitivity, high resistivity and low coefficient of thermal expansion makes it the principal component of all modern strain gauges used. However, Constantan also repres

This study presents a comparative approach to investigate the potentials of two innovative methods for the synthesis of ZnO and Al-doped ZnO. The first method is a precipitation system working in mild hydrothermal conditions (90°C) using a tubular reactor (Segmented Flow Tubular Reactor, SFTR). The second method is a microwave-assisted hydrothermal process working at 250°C - 38 atmospheres. Nanocrystalline ZnO with a high specific surface area (49–68 m2/g) was obtained with both systems. Smaller equiaxed pa

Unstable growth, unlimited urban sprawl, and multiple fragmentations are contemporary urban phenomena requiring new investigations and interpretations of the physical impact of form on today's cities. The city as a living organism with an evolving structur ...

In the past decades, III-nitride semiconductor compounds have attracted an increasing amount of interest due to their applications to blue-violet laser diodes and white light emitting diodes, or for their use as ultraviolet emitting devices for biomedical ...

Epitaxial Laser Metal Forming (E-LMF) consists in impinging a jet of metallic powder onto a molten pool formed by controlled laser heating and thereby, generating epitaxially a single crystal deposit onto a single crystal substrate. It is a near net-shape process for rapid prototyping or repair engineering of single crystal high pressure/high temperature gas turbines blades. Single crystal repair using E-LMF requires controlled solidification conditions in order to prevent the nucleation and growth of cryst

By using synchrotron radiation phase sensitive radiography we have examined the reactions of screw superdislocations or micropipes in silicon carbide single crystals: bundling, twisting, and splitting. To understand the nature of these reactions, a model of micropipe motion during crystal growth has been proposed. Based on this model, a computer simulation of the evolution of a random micropipe ensemble has been performed. The simulation demonstrates that the coalescence of micropipes with opposite-sign Bur

The formation of sub-micron sized particulates has been studied in a low pressure (0.1 mbar) radio-frequency (13.56 MHz) capacitively coupled plasma discharge. Particles are studied in situ by infrared absorption spectroscopy, laser illumination and Cavity Ring Down Absorption Spectroscopy. Transmission Electron Microscopy was applied ex situ for particulates collected during the plasma. We propose that two principal mechanisms may be involved in the formation of these particulates: formation and trapping o

With use of a multimachine pedestal database, essential issues for each regime of ELM types are investigated. They include (i) understanding and prediction of pedestal pressure during type I ELMs, a reference operation mode of a future tokamak reactor; (ii) identification of the operation regime of type II ELMs, which have small ELM amplitude with good confinement characteristics; (iii) identification of the upper stability boundary of type III ELMs for access to the higher confinement regimes with type I o

Transparent single crystals of Pb(Zn-1/3, Nb-2/3)O-3-PbTiO3 (PZN-PT) perovskite have been grown by the slow cooling method in a temperature gradient furnace. The optimization of growth techniques to crystallize PZN-PT with a cubic habitus is described in details. The growth temperature range and cooling rates was carried out in different lead fluxes, Crystal recovery from the residual flux was obtained by different techniques based on liquid flux elimination at the end of the growth process. The best transp

Under certain exptl. conditions-short pyrolysis times, fast heating rates and presence of reducing agent-increasing vaporization temps. led to decreasing losses of Pd as the initial mass was increased between 0.3 and 5.0 ng. When Pd is introduced into the tube at mg levels, as is typical for modifiers, no similar tendency was established and max. loss-free temps. approach 1300 Deg. A procedure for deriving the enthalpy of vaporization was developed which characterizes low-temp. Pd release during pyrolysis.

High quality InP/InGaAsP Distributed Bragg Reflectors (DBRs) are a key element in Vertical Cavity Surface Emitting Laser (VCSELs) for long wavelength (1.55 mu m) applications [1-3]. Because of the small index difference between InP and InGaAsP, more than 30 periods are needed to obtain reflectivities above 99 %, which makes it a challenge for the crystal growth technique. In this paper we present the structural and optical characteristics of such DBRs grown by Chemical Beam Epitaxy (CBE) at high growth rate

In this work, we present a correlation between the morphological characterization of InyAl1−yAs/InxGa1−xAsheterostructures grown on InP substrates for high electron mobility transistors(HEMTs) applications as determined by transmission electron microscopy, and the electrical behavior of the two-dimensional electron gas(2DEG) confined in the InGaAs channel. Our main goal is to analyze the origin of the low and anisotropic values of 2DEGHall mobilities, discussing the effect of the density and asymmetric dist

THE similarity of many patterns formed in non-equilibrium growth processes in physics, chemistry and biology is conspicuous, and many attempts have been made to discover common mechanisms underlying their formation(1). A central question is what causes some patterns to be dendritic (symmetrically branched, like snowflakes) and others fractal (randomly ramified). In general, the transition from fractal to dendritic growth is regarded as a manifestation of the predominance of anisotropy over random noise in t

Laser-heated pedestal growth

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Programing Crystal Growth with DNA Tile Seeds

Uncovering melt pool dynamics and laser absorption mechanisms in laser powder bed fusion through in-situ experiments and high-fidelity multiphysics simulations

Axisymmetric oscillations at L-H transitions in JET: M-mode

Unveiling the Concentration-Dependent Grain Growth of Perovskite Films from One- and Two-Step Deposition Methods: Implications for Photovoltaic Application

Kinetic model for calcium sulfate alpha-hemihydrate produced hydrothermally from gypsum formed by flue gas desulfurization

APCVD of dual layer transparent conductive oxides for photovoltaic applications

Advanced divertor configurations with large flux expansion

Single Crystal Growth of Constantan by Vertical Bridgman Method

Comparison of two innovative precipitation systems for ZnO and Al-doped ZnO nanoparticle synthesis

Morphogenèse de la ville contemporaine : essai sur la multi-échelle

Physics and applications of intersubband transitions in nitride based heterostructures

Marangoni Convection and Fragmentation in Laser Heat Treatment

Synchrotron radiographic study and computer simulation of reactions between micropipes in silicon carbide

Etude de l'origine et de la croissance de particules submicrométriques dans les plasmas radiofréquence réactifs

Understanding of H mode pedestal characteristics using the multimachine pedestal database

Growth and properties of transparent Pb(Zn-1/3, Nb-2/3)O-3-PbTiO3 single crystals with a cubic habitus

Preatomization behavior of palladium in electrothermal atomic-absorption spectrometry

Structural and optical characterization of InP/InGaAsP distributed Bragg reflectors grown by CBE

Well surface roughness and fault density effects on the Hall mobility of In[sub x]Ga[sub 1−x]As/In[sub y]Al[sub 1−y]As/InP high electron mobility transistors

Mechanism of the Transition from Fractal to Dendritic Growth of Surface Aggregates