A5049910969- Metal and Thin Film Mechanics
- Boron and Carbon Nanomaterials Research
- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- MXene and MAX Phase Materials
- Advanced Chemical Physics Studies
- Machine Learning in Materials Science
- Inorganic Chemistry and Materials
- GaN-based semiconductor devices and materials
- Acoustic Wave Resonator Technologies
- Diamond and Carbon-based Materials Research
- Semiconductor materials and devices
- Spectroscopy and Quantum Chemical Studies
- Quantum and electron transport phenomena
- High-pressure geophysics and materials
- Electronic and Structural Properties of Oxides
- Physics of Superconductivity and Magnetism
- Advanced materials and composites
- Advanced Physical and Chemical Molecular Interactions
- Advanced Materials Characterization Techniques
- Metal-Organic Frameworks: Synthesis and Applications
- Titanium Alloys Microstructure and Properties
- Advanced ceramic materials synthesis
- Nuclear Materials and Properties
- Intermetallics and Advanced Alloy Properties
Linköping University
2015-2024
TU Wien
2023
National University of Science and Technology
2018
Atlas Copco (Sweden)
2014
National Research Tomsk State University
2014
Max Planck Institute for the Physics of Complex Systems
2005
Leibniz Institute for Solid State and Materials Research
2004
University of Debrecen
2002-2004
Leibniz Institute for Neurobiology
2004
German Cancer Research Center
2002-2003
The origin of the anomalous, 400% increase piezoelectric coefficient in Sc$_x$Al$_{1-x}$N alloys is revealed. Quantum mechanical calculations show that effect intrinsic. It comes from a strong change response internal atomic coordinates to strain and pronounced softening C$_{33}$ elastic constant. underlying mechanism flattening energy landscape due competition between parent wurtzite so far experimentally unknown hexagonal phases alloy. Our observation provides route for design materials...
Poly-nitrogen compounds have been considered as potential high energy density materials for a long time due to the large number of energetic N-N or N=N bonds. In most cases nitrogen content and stability at ambient conditions are mutually exclusive, thereby making synthesis such challenging. One way stabilize is application pressure. Here, through direct reaction between Fe N
The layered compound BeN${}_{4}$, berillontirene, is a Dirac semimetal with linear dispersion in the vicinity of Fermi energy and two points coinciding energy, similar to graphene.
AlN is challenged as the material choice in important thin film electroacoustic devices for modern wireless communication applications. We present promise of superior electromechanical coupling (kt2), w−ScxAl1−xN by studying its dielectric properties. (0≤x≤0.3) films grown dual reactive magnetron sputtering exhibited low losses along with minor increased constant (ε). Ellipsometry measurements high frequency ε showed good agreement density function perturbation calculations. Our data show...
In this study we discuss the performance of approximate SQS supercell models in describing cubic elastic properties B1 (rocksalt) Ti$_{0.5}$Al$_{0.5}$N alloy by using a symmetry based projection technique. We show on example alloy, that technique can be used to align differently shaped and sized structures for comparison modeling elasticity. Moreover, focus accurately determine constants Zener's type anisotropy Ti$_{0.5}$Al$_{0.5}$N. Our best model, captures both randomness symmetry, results...
Most of the studied two-dimensional (2D) materials are based on highly symmetric hexagonal structural motifs. In contrast, lower-symmetry structures may have exciting anisotropic properties leading to various applications in nanoelectronics. this work we report synthesis nickel diazenide NiN2 which possesses atomic-thick layers comprised Ni2N3 pentagons forming Cairo-type tessellation. The weakly bonded with calculated exfoliation energy 0.72 J/m2, is just slightly larger than that graphene....
Abstract Theoretical modelling predicts very unusual structures and properties of materials at extreme pressure temperature conditions 1,2 . Hitherto, their synthesis investigation above 200 gigapascals have been hindered both by the technical complexity ultrahigh-pressure experiments absence relevant in situ methods analysis. Here we report on a methodology developed to enable static compression terapascal regime with laser heating. We apply this method realize pressures about 600 900...
We propose a design route for the next generation of nitride alloys via concept multicomponent alloying based on self-organization nanoscale formation metastable intermediate products during spinodal decomposition. predict theoretically and demonstrate experimentally that quasi-ternary (TiCrAl)N decompose spinodally into (TiCr)N (CrAl)N-rich nanometer sized regions. The decomposition results in age hardening, while presence Cr within AlN phase delays detrimental wurtzite leading to...
We have performed ab initio calculations for the cubic inverse-perovskite ${\text{Sc}}_{3}E\text{N}$ $(E=\text{Al},\text{Ga},\text{In})$ systems to study their electronic band-structures and elastic properties. In this study, we used accurate augmented plane wave plus local orbital method find equilibrium structural parameters compute full tensors. The obtained single-crystal constants were quantify stiffness of Sc-based ternary nitrides appraise mechanical stability. site-projected density...
Strong compositional-dependent elastic properties have been observed theoretically and experimentally in Ti$_{1-x}$Al$_x$ N alloys. The constant, C$_{11}$, changes by more than 50% depending on the Al-content. Increasing Al-content weakens average bond strength local octahedral arrangements resulting a compliant material. On other hand, it enhances directional (covalent) nature of nearest neighbor bonds that results greater anisotropy higher sound velocities. strong dependence offers new...
Elastic properties of cubic TiN are studied theoretically in a wide temperature interval. First-principles simulations based on ab initio molecular dynamics (AIMD). Computational efficiency the method is greatly enhanced by careful preparation initial state simulation cell that minimizes or completely removes need for equilibration and therefore allows parallel AIMD calculations. constants ${C}_{11}$, ${C}_{12}$, ${C}_{44}$ calculated. A strong dependence predicted, with ${C}_{11}$...
Abstract A nitrogen‐rich compound, ReN 8 ⋅x N 2 , was synthesized by a direct reaction between rhenium and nitrogen at high pressure temperature in laser‐heated diamond anvil cell. Single‐crystal X‐ray diffraction revealed that the crystal structure, which is based on framework, has rectangular‐shaped channels accommodate molecules. Thus, despite very synthesis pressure, exceeding 100 GPa, an inclusion compound. The amount of trapped (x) depends conditions. polydiazenediyl chains [−N=N−] ∞...
Density functional theory is a standard model for condensed matter and computational material science. The accuracy of density limited by the employed approximation to exchange-correlation functional. Recently, so-called strongly constrained approprietly normed (SCAN) has received lot attention due promising results covalent, metallic, ionic, as well hydrogen- van der Waals-bonded systems alike. In this work we focus on assessing performance SCAN itinerant magnets calculating basic...
Available information concerning the elastic moduli of refractory carbides at temperatures (T) relevance for practical applications is sparse and/or inconsistent. We carry out ab initio molecular dynamics (AIMD) simulations T = 300, 600, 900, and 1200 K to determine temperature-dependences constants rocksalt-structure (B1) TiC, ZrC, HfC, VC, TaC compounds as well multicomponent high-entropy (Ti,Zr,Hf,Ta,W)C (V,Nb,Ta,Mo,W)C. The second order are calculated by least-square fitting analytical...
Abstract Accelerated design of hard-coating materials requires state-of-the-art computational tools, which include data-driven techniques, building databases, and training machine learning models. We develop a heavily automated high-throughput workflow to build database industrially relevant materials, such as binary ternary nitrides. use the toolkit automate density functional theory calculation workflow. present results, including elastic constants that are key parameter determining...
Although titanium nitride (TiN) is among the most extensively studied and thoroughly characterized thin-film ceramic materials, detailed knowledge of relevant dislocation core structures lacking. By high-resolution scanning transmission electron microscopy (STEM) epitaxial single crystal (001)-oriented TiN films, we identify different types their structures. These include, besides expected primary full a/2{110}<1$\bar{1}$0> dislocation, Shockley partial dislocations a/6{111}<11$\bar{2}$>...
Carbon nitrides featuring three-dimensional frameworks of CN
In a recent experiment, Weisheit et al (2007 Science 315 349) demonstrated that the coercivity of thin L10 FePt and FePd films can be modified by external electric field in an electrochemical environment. Here, this observation is confirmed density functional calculations for intrinsic magnetic anisotropy. The origin effect clarified means general simple method to simulate charged metal surfaces. It predicted CoPt much more susceptible than films.
We discover that hcp phases of Fe and ${\mathrm{Fe}}_{0.9}{\mathrm{Ni}}_{0.1}$ undergo an electronic topological transition at pressures about 40 GPa. This change the Fermi surface manifests itself through anomalous behavior Debye sound velocity, $c/a$ lattice parameter ratio, M\"ossbauer center shift observed in our experiments. First-principles simulations within dynamic mean field approach demonstrate is induced by many-electron effects. It absent one-electron calculations represents a...
Recently, ScAlN alloys attracted attention for their giant piezoelectric moduli. In this study the response of wurtzite group-III nitrides AlN, GaN, and InN mixed with 50 mol$%$ ScN or YN is investigated using ab initio calculations. We confirm that energy flattening phenomenon gives rise to simultaneous appearance elastic softening local structural instability, explains enhanced piezoelectricity alloys. Furthermore, we present a volume matching condition an efficient search new materials....
Ti1−xAlxN is a technologically important alloy that undergoes process of high temperature age-hardening strongly influenced by its elastic properties. We have performed first principles calculations the constants and anisotropy using symmetry imposed force constant dependent effective potential method, which include lattice vibrations therefore effects temperature, including thermal expansion intrinsic anharmonicity. These are compared with in situ x-ray diffraction measurements parameter....
The potential of quarternary wurtzite ${\mathrm{TM}}_{x/2}{\mathrm{M}}_{x/2}{\mathrm{Al}}_{1\ensuremath{-}x}\mathrm{N}$ ($\mathrm{TM}=\text{Ti}$, Zr, Hf; $\mathrm{M}=\text{Mg}$, Ca, Zn) alloys for piezoelectric applications is investigated using first-principles calculations. All considered show increased response compared to pure AlN, and competing with the best ternary system proven date: ScAlN....