Combination of HAADF-STEM and ADF-STEM Tomography for Core–Shell Hybrid Materials

Characterization of core–shell type nanoparticles in 3D by transmission electron microscopy (TEM) can be very challenging. Especially when both heavy and light elements coexist within the same nanostructure, artifacts in the 3D reconstruction are often present. A representative example would be a particle comprising an anisotropic metallic (Au) nanoparticle coated with a (mesoporous) silica shell. To obtain a reliable 3D characterization of such an object, a dose-efficient strategy is proposed to simultaneously acquire high-angle annular dark-field scanning TEM and annular dark-field tilt series for tomography. The 3D reconstruction is further improved by applying an advanced masking and interpolation approach to the acquired data. This new methodology enables us to obtain high-quality reconstructions from which also quantitative information can be extracted. This approach is broadly applicable to investigate hybrid core–shell materials

Structure and vacancy distribution in copper telluride nanoparticles influence plasmonic activity in the near-infrared

Copper chalcogenides find applications in different domains including photonics, photothermal therapy and photovoltaics. CuTe nanocrystals have been proposed as an alternative to noble metal particles for plasmonics. Although it is known that deviations from stoichiometry are a prerequisite for plasmonic activity in the near-infrared, an accurate description of the material and its (optical) properties is hindered by an insufficient understanding of the atomic structure and the influence of defects, especially for materials in their nanocrystalline form. We demonstrate that the structure of Cu1.5±xTe nanocrystals can be determined using electron diffraction tomography. Real-space high-resolution electron tomography directly reveals the three-dimensional distribution of vacancies in the structure. Through first-principles density functional theory, we furthermore demonstrate that the influence of these vacancies on the optical properties of the nanocrystals is determined. Since our methodology is applicable to a variety of crystalline nanostructured materials, it is expected to provide unique insights concerning structure–property correlations

The Effect of Democratic Zoning System on Nigeria Economy: Evidence of Niger State

<p>The introduction of the zoning system into Nigeria political space was to aid the smooth rotation of key political positions across the country. This policy is to achieve fairness, peace and equitable distribution of resource. Its adverse effect on the economy is thus something to worry about. Therefore, the study examines the effect of democratic zoning system on the economy of Nigeria, with special reference to Niger state. Employing descriptive statistics and multiple regressions. The results revealed that the elements of democratic zoning <em>vis-à-vis; </em>peace, equity, unity and justice has a positive and significant effect on the growth of the Nigeria economy. The authors thus recommends the government at both levels should focus on providing simultaneous development projects to pave way for peace and unity, zoning system should be incorporated into the Nigeria constitution, unbiased and equitable distribution of resources across the economy.</p>DOI: <a href="http://dx.doi.org/10.15408/etk.v17i1.6592">10.15408/etk.v17i1.6592</a