1,265 research outputs found
Atomic defects and dopants in ternary Z-phase transition-metal nitrides CrMN with M=V, Nb, Ta investigated with density functional theory
A density functional theory study of atomic defects and dopants in ternary
Z-phase transition-metal nitrides CrMN with M=V, Nb, or Ta is presented.
Various defect formation energies of native point defects and of substitutional
atoms of other metal elements which are abundant in the steel as well, are
evaluated. The dependence thereof on the thermodynamic environment, i.e. the
chemical conditions of a growing Z-phase precipitate, is studied and different
growth scenarios are compared. The results obtained may help to relate results
of experimental atomic-scale analysis, by atom probe tomography or transmission
electron microscopy, to the theoretical modeling of the formation process of
the Z phase from binary transition metal nitrides
Compositional optimization of hard-magnetic phases with machine-learning models
Machine Learning (ML) plays an increasingly important role in the discovery
and design of new materials. In this paper, we demonstrate the potential of ML
for materials research using hard-magnetic phases as an illustrative case. We
build kernel-based ML models to predict optimal chemical compositions for new
permanent magnets, which are key components in many green-energy technologies.
The magnetic-property data used for training and testing the ML models are
obtained from a combinatorial high-throughput screening based on
density-functional theory calculations. Our straightforward choice of
describing the different configurations enables the subsequent use of the ML
models for compositional optimization and thereby the prediction of promising
substitutes of state-of-the-art magnetic materials like NdFeB with
similar intrinsic hard-magnetic properties but a lower amount of critical
rare-earth elements.Comment: 12 pages, 6 figure
From metastable to stable modifications-in situ Laue diffraction investigation of diffusion processes during the phase transitions of (GeTe)(n)Sb2Te3 (6 < n < 15) crystals.
Temperature dependent phase transitions of compounds (GeTe)nSb2Te3 (n = 6, 12, 15) have been investigated by in situ microfocus Laue diffraction. Diffusion processes involving cation defect ordering at B300 8C lead to different nanostructures which are correlated to changes of the thermoelectric characteristics
- …