Metallic line defect in wide-bandgap transparent perovskite BaSnO3

A line defect with metallic characteristics has been found in optically transparent BaSnO3 perovskite thin films. The distinct atomic structure of the defect core, composed of Sn and O atoms, was visualized by atomic-resolution scanning transmission electron microscopy (STEM). When doped with La, dopants that replace Ba atoms preferentially segregate to specific crystallographic sites adjacent to the line defect. The electronic structure of the line defect probed in STEM with electron energy-loss spectroscopy was supported by ab initio theory, which indicates the presence of Fermi level–crossing electronic bands that originate from defect core atoms. These metallic line defects also act as electron sinks attracting additional negative charges in these wide-bandgap BaSnO3 films.

Metallic Line Doubling in the Spectra of the Variable Star R Scuti

In this work, we present spectroscopic results of the variable star R Scuti, obtained during the campaign of measures led in 2016 at the Oukaimeden observatory in Morrocco. High resolution spectra (R ≍ 12 000) were obtained between 4289 Å and 7125 Å. This intensive observing campaign spanned over 26 nights from June to November 2016.

Micro-Contact Models for Metallic Line-Contact Based on Measured Surface Profile

In order to study the dry rough line-contact mechanism between two longitudinally rough metallic surfaces, the measured profile is mathematically described by quadratic functions for the application of the existing micro-contact models. The mechanical parameters are determined using the different approximating criteria. Next, based on these deterministic parameters, different micro-contact models are employed and extended to predict the characteristics of a line-contact. Comparison of different theoretical calculation results reveals that the greater maximum values of the contact deformation and the ratio of real to nominal contact area are predicted by the Hertz model as compared to the micro-contact models considering the elastoplastic deformation, and that the KE (Kogut and Etsion) and JG (Jackson and Green) models predict closer results. It is also found that when the rough surfaces are described by quadratic functions according to the same area criterion or same root mean square (RMS) criterion, the line-contact responses between them prescribed by any micro-contact models have the same tendency.