Publications associées à Defects in a-GaN grown on r-sapphire by hydride vapor phase epitaxy

Solute-strengthening in metal alloys with short-range order

Recent surging interest in strengthening of High Entropy Alloys (HEAs) with possible chemical ordering motivates the development of new theory. Here, an existing theory for random alloys that accounts for solute-dislocation and solute–solute interactions i ...

2024

III-N blue-emitting epi-structures with high densities of dislocations: Fundamental mechanisms for efficiency improvement and applications

Pierre Christophe Lottigier

Since the dawn of humanity, human beings seeked to light their surroundings for their well-being, security and development. The efficiency of ancient lighting devices, e.g. oil lamps or candles, was in the order of 0.03-0.04% and jumped to 0.4-0.6% with th ...

EPFL2024

Mapping orthorhombic domains with geometrical phase analysis in rare-earth nickelate heterostructures

Jean-Marc Triscone, Duncan Thomas Lindsay Alexander, Bernat Mundet

Most perovskite oxides belong to the Pbnm space group, composed of an anisotropic unit cell, A-site antipolar displacements, and oxygen octahedral tilts. Mapping the orientation of the orthorhombic unit cell in epitaxial heterostructures that consist of at ...

Aip Publishing2024

Dislocation Hardening in a New Manufacturing Route of Ferritic Oxide Dispersion-Strengthened Fe-14Cr Cladding Tube

Roland Logé

The microstructure evolution associated with the cold forming sequence of an Fe-14Cr-1W-0.3Ti-0.3Y2O3 grade ferritic stainless steel strengthened by dispersion of nano oxides (ODS) was investigated. The material, initially hot extruded at 1100 degrees C an ...

MDPI2024

The influence of lattice misfit on screw and edge dislocation-controlled solid solution strengthening in Mo-Ti alloys

William Curtin, Carolina Baruffi, You Rao

Mo-Ti alloys form solid solutions over a wide range of compositions, with lattice misfit parameters increasing significantly with titanium content. This indicates a strong increase in the critical stress for edge dislocation motion. Here, we probe the tran ...

SPRINGERNATURE2023

Simultaneous strength and ductility enhancement of wire-arc directed energy deposited Al-Cu alloy by interlayer laser shock peening

Ke Huang, Yandong Jing

Wire-arc directed energy deposition (wire-arc DED), recognized for its ability to produce large-scale parts, has gained considerable attention. However, a critical issue with this method is the high prevalence of internal porosity defects found in the manu ...

Elsevier Science Sa2023

Vacancy segregation and intrinsic coordination defects at (111) twist grain boundaries in diamond

Christian Brandl, Carolina Baruffi

High radiation damage resistance has become increasingly important for applications of functional materials in harsh environments. The high radiation damage resistance diamond cubic carbon is a unique material which is considered for radiation environments ...

Pergamon-Elsevier Science Ltd2023

Lattice Green's function method for Atomistic/Continuum coupling

Ankit Gupta

Metal plasticity is an inherently multiscale phenomenon due to the complex long-range field of atomistic dislocations that are the primary mechanism for plastic deformation in metals. Atomistic/Continuum (A/C) coupling methods are computationally efficient ...

EPFL2023

Zn3P2 as an earth-abundant photovoltaic material: from growth to device

Rajrupa Paul

The development of cost-effective and earth-abundant semiconducting materials is imperative for the sustainable deployment of photovoltaic technology. Zinc phosphide (Zn3P2) is a promising candidate for terawatt-scale electricity generation. It has a near- ...

EPFL2023

Scalable Approaches to III-V Nanowires for Photodetection

Nicholas Paul Morgan

III-V semiconductor nanowires have unique properties that make them ideal for advanced photodetectors on inexpensive substrates. For example, they exhibit enhanced or polarization-dependent light absorption, they can form complex heterostructures, and thei ...

EPFL2023

GeSn as next-generation material for short-wave infrared single-photon detection

Andrea Giunto

In recent years, the automotive industry has aspired to bring self-driving vehicles to the general public and light detection and ranging (LiDAR) sensors have emerged as the preferred solution for car vision systems. At present, LiDAR technologies employ e ...

EPFL2023

Simple shear extrusion versus equal channel angular pressing: A comparative study on the microstructure and mechanical properties of an Mg alloy

Cyril Cayron, Roland Logé, Aryan Rezaei Rad

Two severe plastic deformation (SPD) techniques of simple shear extrusion (SSE) and equal channel angular pressing (ECAP) were employed to process an extruded Mg -6Gd -3Y -1.5Ag (wt%) alloy at 553 K for 1, 2, 4 and 6 passes. The microstructural evolutions ...

KEAI PUBLISHING LTD2023

A low-temperature prismatic slip instability in Mg understood using machine learning potentials

William Curtin, Xin Liu, Binglun Yin, Tao Liu

Prismatic slip in magnesium at temperatures T

PERGAMON-ELSEVIER SCIENCE LTD2023

Microscopic Digital Image Correlation Analysis of Strain Distributions in Stainless Steel 316L Induced by Multiaxial Cyclic Loading

Elif Cansu Kursun

Fatigue damage in materials results in localized strain at the microstructural level. In many engineering components of the cooling circuits of nuclear power plants, where austenitic steels are used, the material experiences multiaxial cyclic loading, eith ...

EPFL2023

Effect of Mo addition on the mechanical and tribological properties of magnetron sputtered TiN films

Sami Rtimi

Ternary-based titanium nitride (TiN) thin films have drawn attention toward rational applications due to their wear resistance, high hardness, and corrosion resistance. The influence of Mo content on the structural, tribo-logical, and mechanical properties ...

ELSEVIER SCIENCE SA2023

Strengthening mechanisms in dilute and random solid solution high-entropy BCC alloys

Alireza Ghafarollahi

Tuning the mechanical properties of metals, including strength, through adjusting the type and/or concentration of added solute elements, has been recognized as an effective way to design and produce materials with desired or optimized mechanical propertie ...

EPFL2022

Screw vs. edge dislocation strengthening in body-centered-cubic high entrophy alloys and implications for guided alloy design

William Curtin, Francesco Maresca, Carolina Baruffi

Body-centered-cubic (BCC) high entropy alloys (HEAs) can show exceptionally high strength up to high temperatures. Mechanistic theories are needed to guide alloy discovery within the immense multicomponent HEA compositional space. Here, two new theories fo ...

SPRINGER HEIDELBERG2022

Wafer-scale MoS2 with water-vapor assisted showerhead MOCVD

Andras Kis, Aleksandra Radenovic, Yanfei Zhao, Michal Daniel Macha, Mukeshchand Thakur, Jing Zhang, Mukesh Kumar Tripathi, Hyungoo Ji

Among numerous thin film synthesis methods, metalorganic chemical vapor deposition performed in a showerhead reactor is the most promising one for broad use in scalable and commercially adaptable two-dimensional material synthesis processes. Adapting the m ...

ROYAL SOC CHEMISTRY2022

Demonstrating and Unraveling a Controlled Nanometer-Scale Expansion of the Vacancy Defects in Graphene by CO2

Kumar Varoon Agrawal, Luis Francisco Villalobos Vazquez de la Parra, Kuang-Jung Hsu

A controlled manipulation of graphene edges and vacancies is desired for molecular separation, sensing and electronics applications. Unfortunately, available etching methods always lead to vacancy nucleation making it challenging to control etching. Herein ...

Wiley-VCH Verlag GmbH2022

Modeling of precipitate strengthening with near-chemical accuracy: case study of Al-6xxx alloys

William Curtin, Yi Hu

Many metal alloys are strengthened by controlling precipitation to achieve an optimal peak-aged condi-tion where the strength-limiting processes of precipitate shearing and Orowan looping are thought to be comparable. Qualitative models have long captured ...

PERGAMON-ELSEVIER SCIENCE LTD2022