Electron holographic tomography Wolf, D.; Lubk, A.; Röder, F. ...
Current opinion in solid state & materials science,
06/2013, Letnik:
17, Številka:
3
Journal Article
Recenzirano
•Electron holographic tomography provides a unique access to 3D electric potential at the nanometer scale.•It has been successfully applied to reveal the 3D potential in nanowires and across p–n ...junctions in semiconductors.•The prospects of the 3D reconstruction of magnetic vector fields as well as atomic crystal potentials are discussed.
The exact knowledge about intrinsic electrostatic potentials and in particular their three-dimensional distribution at the nanometer scale is a key prerequisite for understanding the solid state properties. Electron holographic tomography (EHT), the combination of off-axis holography with tomography in the transmission electron microscope, provides a unique access to this information. We review the development and application of automated EHT to reconstruct 3D potentials in nanostructures such as the mean inner potential of a material or the diffusion potential across p–n junctions in semiconductors. We also discuss future challenges of the 3D reconstruction of electric crystal potentials at atomic resolution and magnetostatic fields as well as ways to overcome present limitations of the method.
Ion-irradiation-induced hardening is investigated on six selected reactor pressure vessel (RPV) steels. The steels were irradiated with 5 MeV Fe
2+
ions at fluences ranging from 0.01 to 1.0 ...displacements per atom (dpa) and the induced hardening of the surface layer was probed with nanoindentation. To separate the indentation size effect and the substrate effect from the irradiation-induced hardness profile, we developed an analytic model with the plastic zone of the indentation approximated as a half sphere. This model allows the actual hardness profile to be retrieved and the measured hardness increase to be assigned to the respective fluence. The obtained values of hardness increase vs. fluence are compared for selected pairs of samples in order to extract effects of the RPV steel composition. We identify hardening effects due to increased levels of copper, manganese-nickel and phosphorous. Further comparison with available neutron-irradiated conditions of the same heats of RPV steels indicates pronounced differences of the considered effects of composition for irradiation with neutrons vs. ions.
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