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Inline electron holography, the recovery of amplitude and phase of an electron wave function having passed through a thin specimen from a focal series recorded in a transmission electron microscope is being applied in many labs worldwide. At medium range magnification (i.e. typically ≥ 0 . 8 nm where the lattice of small unit cell crystals such as silicon is not resolved), where the defocus needs to be varied over a rather large range of several hundred nm or even μ m, the retrieval of low spatial frequency information is severely affected by the choice of experimental parameters as well as the way of data normalization. Methods to quantitatively analyze the reliability of phase maps obtained by inline electron holography are presented, and data recorded and processed in different ways are compared. While, even under optimized conditions, the phase reconstructed from an experimental focal series still lacks very low spatial frequency components, regularization schemes exist and are demonstrated to effectively hide artifacts associated with this lack of information.

Improved multiphoton¿excited imaging and microspectroscopy require nanoprobes that can give different nonlinear optical signals. Here, composite nanostructures with a barium titanate core and a plasmonic moiety at their surface are synthesized and characterized. It is found that the core provides a high second¿order nonlinear susceptibility for sensitive second harmonic generation (SHG) imaging in living cells. As a second function in the two¿photon regime, the plasmonic part yields high local fields for resonant and nonresonant surface enhanced hyper Raman scattering (SEHRS). SEHRS complements the one¿photon surface enhanced Raman scattering (SERS) spectra that are also enhanced by the plasmonic shells. Barium titanate silver core¿shell (Ag@BaTiO3) composites are specifically suited for SEHRS and SHG excited at 1064 nm, while gold at barium titanate (Au@BaTiO3) nanoparticles can be useful in a combination of SHG and SERS at lower wavelengths, here at 785 nm and 850 nm. The theoretical models show that the optical properties of the BaTiO3 dielectric core depend on probing frequency, shape, size, and plasmonic properties of the surrounding gold nanoparticles so that they can be optimized for a particular type of experiment. These versatile, tunable probes give new opportunities for combined multiphoton probing of morphological structure and chemical properties of biosystems., Funding by ERC Starting Grant No. 259432 MULTIBIOPHOT to J.K., a Chemiefonds Fellowship (FCI) to F.M., and DFG GSC 1013 SALSA to V.Z. are gratefully acknowledged. A.N., R.E., and J.A. acknowledge the National Project FIS2016‐80174‐P from the MICINN, Grant No. IT1164‐19, for research groups of the Basque University system from the Department of Education of the Basque Government and Elkartek project KK‐2018/00001 from the Department of Economical Development and Infrastructures of the Basque Government.

Electron energy-loss spectroscopy and energy-dispersive X-ray spectroscopy are two of the most common means for chemical analysis in the scanning transmission electron microscope. The marked progress of the instrumentation hardware has made chemical analysis at atomic resolution readily possible nowadays. However, the acquisition and interpretation of atomically resolved spectra can still be problematic due to image distortions and poor signal-to-noise ratio of the spectra, especially for investigation of energy-loss near-edge fine structures. By combining multi-frame spectrum imaging and automatic energy-offset correction, we developed a spectrum imaging technique implemented into customized DigitalMicrograph scripts for suppressing image distortions and improving the signal-to-noise ratio. With practical examples, i.e. SrTiO 3 bulk material and Sr-doped La 2 CuO 4 superlattices, we demonstrate the improvement of elemental mapping and the EELS spectrum quality, which opens up new possibilities for atomically resolved EELS fine structure mapping.

The surface effect on the photodetection of metal oxide nanostructures acting as a double-edged sword achieves ultrahigh photogain but unavoidably prolongs the response time due to slow oxygen adsorption/desorption processes. In this study, we break the compromise to enhance the UV photogain by 3 orders of magnitude as well as increase the photoresponse speed by 5 times via incorporating open-circuit p–n nanoscale heterojunctions (NHJs) by forming single-crystalline p-NiO nanoparticles on n-ZnO nanowires. This is because the formation of NHJs enhances surface band bending of ZnO nanowires, improving the spatial separation efficiency of photogenerated electrons and holes, and passivates the ZnO surfaces by minimizing the interaction of photocarriers with chemisorbed oxygen molecules. The concept using NHJs explores a new pathway toward ultrafast and supersensitive photodetection.

The microstructure evolution of sputtered gadolinium oxide nanocrystal (NC) memory devices upon annealing has been characterized in detail by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). TEM results indicate that the as-deposited film is composed of metallic Gd clusters embedded in an amorphous Gd x O y matrix. The Gd clusters undergo phase transformation to oxide NCs upon annealing, reaching a maximum density of 7.9–9.1 × 10 11 cm − 2 at 850 °C, which is consistent with the largest memory window width. Upon annealing at even higher temperature, TEM diffraction patterns and XPS composition profiles indicate apparent Si diffusion into the NC layer, probably from the SiO 2 tunneling oxide or the Si substrate, leading to the formation of gadolinium silicate NCs. The presence of silicate NCs gradually deteriorates the device performance due to the reduction of barrier confinement for stored charges, although the dot density is only marginally decreased. The results suggest that the optimum memory device performance is dominated by not only the most considered size and density of NCs, but also the composition and phase inside.

The microstructure, growth mechanism, and ferromagnetic (FM)/antiferromagnetic (AFM) coupling have been discussed in Ni:ZnO nanorod/Zn:NiO nanowall composite structures. The composite structures were synthesized by a hydrothermal method at 90 °C. A systematic investigation of high-resolution transmission electron microscopy, X-ray absorption spectroscopy, and magnetization studies reveals that the as-synthesized product shows FM behavior at room temperature, whereas the annealed sample shows mixed (FM/AFM) magnetic behavior. A detectable magnetic exchange coupling between FM/AFM has been demonstrated by magnetization measurements in the annealed products. The observed room-temperature FM behavior in these nanostructures was interpreted in terms of bound magnetic polarons.