김미영 교수

A combination of experiments and first-principles calculations is used to show that grain boundaries in SrTiO3 are intrinsically nonstoichiometric. Total-energy calculations reveal that the introduction of nonstoichiometry into the grain boundaries is energetically favorable and results in structures that are consistent with atomic-resolution Z-contrast micrographs. Electron energy-loss spectra provide direct evidence of nonstoichiometry. These results and calculations for nonstoichiometric grai

Polymer-stabilized blue phase liquid crystal displays based on the Kerr effect are emerging due to their submillisecond response time, wide view and simple fabrication process. However, the conventional in-plane switching device exhibits a relatively high operating voltage because the electric fields are restricted in the vicinity of the electrode surface. To overcome this technical barrier, we propose a partitioned wall-shaped electrode configuration so that the induced birefringence is uniform

, are the most promising candidates for lithium-ion battery cathodes. They generally consist of ≈10 µm spherical particles densely packed with smaller particles (0.1-1 µm), called secondary and primary particles, respectively. The micrometer- to nanometer-sized particles are critical to the battery performance because they affect the reaction capability of the cathode. Herein, the crystal structure of the primary particles of NCM materials is revisited. Elaborate transmission electron microscopy

) was greatly enhanced by the ant farm like structure. The composites possess excellent thermal and EMI SE characteristics, thus can be applied in areas, such as mobile phones, military utensils, heat-emitting electronic devices, automobiles and radars.

The nature of magnetic ordering in LaCoO 3 epitaxial thin films has been the subject of considerable debate. We present direct observations of the spin-state modulation of Co ions in LaCoO 3 epitaxial thin films on an atomic scale using aberration-corrected scanning transmission electron microscopy (STEM), electron energy loss spectroscopy (EELS), and ab initio calculations based on density functional theory (DFT) calculations. The results of an atomic-resolution STEM/EELS study indicate that th

Plan-view and cross-sectional transmission electron microscopy images show the microstructural properties of GaN thin films grown on graphene layers, including dislocation types and density, crystalline orientation and grain boundaries. The roles of ZnO nanowalls and GaN intermediate layers in the heteroepitaxial growth of GaN on graphene, revealed by cross-sectional transmission electron microscopy, are also discussed.

Abstract Manganese oxide (α‐MnO 2 ) has been considered a promising energy material, including as a lithium‐based battery electrode candidate, due to its environmental friendliness. Thanks to its unique 1D [2 × 2] tunnel structure, α‐MnO 2 can be applied to a cathode by insertion reaction and to an anode by conversion reaction in corresponding voltage ranges, in a lithium‐based battery. Numerous reports have attributed its remarkable performance to its unique tunnel structure; however, the preci

Predicting the performance of thermoelectric materials requires precise knowledge of the Fermi surface and near-lying electronic structures. While ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$ is a major constituent of the active layers in commercial thermoelectric coolers, ab initio electronic structure theory heretofore has failed to reproduce the measured experimental band gap. Herein, we report self-consistent screened-exchange local density approximation (sX-LDA) calculations for the electronic stru

Abstract Three central themes in the study of the phenomenon of resistive switching are the nature of the conducting phase, why it forms, and how it forms. In this study, the answers to all three questions are provided by performing switching experiments in situ in a transmission electron microscope on thin films of the model system polycrystalline SrTiO 3 . On the basis of high‐resolution transmission electron microscopy, electron‐energy‐loss spectroscopy and in situ current–voltage measurement