Increasing Spatial Fidelity and SNR of 4D-STEM Using Multi-Frame Data Fusion

4D-STEM, in which the 2D diffraction plane is captured for each 2D scan position in the scanning transmission electron microscope (STEM) using a pixelated detector, is complementing, and increasingly replacing existing imaging approaches. However, at present the speed of those detectors, although having drastically improved in the recent years, is still 100 to 1,000 times slower than the current PMT technology operators are used to. Regrettably, this means environmental scanning-distortion often limits the overall performance of the recorded 4D data. Here, we present an extension of existing STEM distortion correction techniques for the treatment of 4D data series. Although applicable to 4D data in general, we use electron ptychography and electric-field mapping as model cases and demonstrate an improvement in spatial fidelity, signal-to-noise ratio (SNR), phase precision, and spatial resolution.

Silver Oxide Nanostructure: a Study on Physical Properties at Different Chemical Interaction Time

Chemical bath deposition method was employed for the deposition of smooth quantum size Ag2O nanostructure thin film on glass substrate at three different chemical interaction times. The structural properties shows the demonstration of Ag2O cubic structure at (002) diffraction plane. Optical properties reflect the dependence of energy gab on the interaction time with moderate band gab energy of about 2.25eV.Other physical properties such as SEM, AFM, was also investigated.

A Content Hiding Method for Digital Hologram Using Multiple Fresnel Diffraction

A digital hologram (DH) is so highly valued that it needs to be protected from exposure to an unpermitted person, which could be done by a content encryption. We propose an encryption scheme for digital holograms, whose goal is to hide their information with maximal visual distortion and minimal ration of the encrypted data. It uses the characteristics of the Fresnel transform and signal processing techniques. As the diffraction distance increases the region containing the object information relative to the whole diffraction plane becomes smaller. Therefore our scheme diffracts a given digital hologram twice: the first transform for reconstructing the image contained by the hologram and the second transform for concentrating the energy of the object into a small region. Then only the energy-concentrated region is encrypted to reduce the amount of data to be encrypted. Experimental results show that when the diffraction distance of the second transform is about 20 m, the encryption ratio is only 0.0058% of the hologram data, which is enough to hide the object information unrecognizably.

Dependence of X-ray asymmetrical Bragg case plane-wave rocking curves on the deviation from exact Bragg orientation in and perpendicular to the diffraction plane

For the asymmetrical Bragg case the X-ray plane-wave reflection coefficients and rocking-curve dependences on the deviation angles from the exact Bragg orientation in the diffraction plane and in the direction perpendicular to the diffraction plane are analysed. The region of total reflection and its size dependence on two deviation angles are analysed as well. New peculiarities of the rocking curves are obtained.

Dependence of X-ray plane-wave rocking curves on the deviation from exact Bragg orientation in and perpendicular to the diffraction plane for the asymmetrical Laue case

For the asymmetrical Laue case the X-ray plane-wave transmission and reflection coefficients and rocking curves are analysed as a function of the deviation angles from the exact Bragg orientation in the diffraction plane and in the direction perpendicular to the diffraction plane. New peculiarities of the rocking curves are obtained. The peculiarities of both the effective absorption coefficient and rocking curves in thick crystals are also investigated.

Synthesis and Thermoelectric Properties of ZnO/Cu2SnSe3 Composites

Addition of nanoparticles into bulk materials is an efficient way to enhance the performance of thermoelectric materials. The nanoZnO particles were introduced into the Cu2SnSe3 matrix by ball milling method, and the ZnO/Cu2SnSe3 composites were fabricated by spark plasma sintering (SPS) technology. The phase constitution and microstructure were characterized by XRD, FESEM. The effects of nanoZnO particles on the electrical and thermal transport were investigated and discussed. The diffraction spectra of all composites samples well corresponded to that of the matrix diffraction plane. The nanoZnO agglomerated into irregular clusters with the size lager than 200nm and distributed on the grain boundary or the surface of Cu2SnSe3 grain, which significantly reduce the lattice thermal conductivity by scattering middle-long wavelength phonons. The optimal ZT value was obtained from the composite sample of 2.4 vol. % ZnO, which is 1.3 times as large as that of the Cu2SnSe3 matrix.