A reformulated implementation of single-sideband ptychography enables analysis and display of live detector data streams in 4D scanning transmission electron microscopy (STEM) using the LiberTEM open-source platform. This is combined with live first moment and further virtual STEM detector analysis. Processing of both real experimental and simulated data shows the characteristics of this method when data are processed progressively, as opposed to the usual offline processing of a complete data set. In particular, the single-sideband method is compared with other techniques such as the enhanced ptychographic engine in order to ascertain its capability for structural imaging at increased specimen thickness. Qualitatively interpretable live results are obtained also if the sample is moved, or magnification is changed during the analysis. This allows live optimization of instrument as well as specimen parameters during the analysis. The methodology is especially expected to improve contrast- and dose-efficient in situ imaging of weakly scattering specimens, where fast live feedback during the experiment is required.

SrTiO3 is an important photocatalyst for hydrogen evolution under solar light, a promising way to solve energy shortage. However, a rapid and efficient method to synthesize high-performance SrTiO3 used for this purpose still remains a challenge. In this work, we successfully prepared SrTiO3 catalyst with narrowed band gap through a rapid laser-melting method of a limited reaction time to seconds. The prepared SrTiO3 catalyst, which has a band gap of 3.05 eV, presents enhanced photocatalytic performance for hydrogen evolution under visible light. The evolution rate of laser-melted SrTiO3 is approximately 3.5 times higher than that of pristine SrTiO3. In addition, the magnetism in laser-melted SrTiO3 is also enhanced, which could not be observed in pristine SrTiO3, confirming the defective structure of the obtained laser-melted SrTiO3. The proposed laser-melting method will be a promising way to rapidly and efficiently synthesize homogeneous, solar-driven SrTiO3 photocatalyst for hydrogen evolution with rich defects and thus high-performance.

We report our effort to quantify atomic-scale chemical maps obtained by collecting energy-dispersive X-ray spectra (EDS) using scanning transmission electron microscopy (STEM) (STEM-EDS). With thin specimen conditions and localized EDS scattering potential, the X-ray counts from atomic columns can be properly counted by fitting Gaussian peaks at the atomic columns, and can then be used for site-by-site chemical quantification. The effects of specimen thickness and X-ray energy on the Gaussian peak width are investigated using SrTiO3 (STO) as a model specimen. The relationship between the peak width and spatial resolution of an EDS map is also studied. Furthermore, the method developed by this work is applied to study cation occupancy in a Sm-doped STO thin film and antiphase boundaries (APBs) present within the STO film. We find that Sm atoms occupy both Sr and Ti sites but preferably the Sr sites, and Sm atoms are relatively depleted at the APBs likely owing to the effect of strain.

We studied a lattice distortion and relaxation of BaTiO3(BT) thin films grown on SrTiO3 (001) substrates(ST) by a molecular beam epitaxy method using an oxygen radical source RT were prepared by alternately deposition of BaO and TiO2 layers, and the structure of the thin films was evaluated by X-ray diffraction, reflection high energy electron diffraction, transmission electron microscopy, atomic force microscopy, coaxial impact collision ion scattering spectroscopy and X-ray photoelectron spectroscopy The lattice constants of the films varied with distance from the interface of BT and ST It was found that lattice distortion and relaxation of BT On the other hand, the surface analysis indicated that adsorbed oxygen was enriched on the BaO-terminated surface in comparison with the TiO2-terminated surface Then we proposed new mechanism of BT thin film growth with adsorbed oxygen.