Synthesis and Nanostructure Investigation of Hybrid β-Ga2O3/ZnGa2O4 Nanocomposite Networks with Narrow-Band Green Luminescence and High Initial Electrochemical Capacity

The material design of functional “aero”-networks offers a facile approach to optical, catalytical, or and electrochemical applications based on multiscale morphologies, high large reactive area, and prominent material diversity. Here in this paper, the synthesis and structural characterization of a hybrid β-Ga₂O₃/ZnGa₂O₄ nanocomposite aero-network are presented. The nanocomposite networks are studied on multiscale with respect to their micro- and nanostructure by X-ray diffraction (XRD) and transmission electron microscopy (TEM) and are characterized for their photoluminescent response to UV light excitation and their electrochemical performance with Li-ion conversion reaction. The structural investigations reveal the simultaneous transformation of the precursor aero-GaN(ZnO) network into hollow architectures composed of β-Ga₂O₃ and ZnGa₂O₄ nanocrystals with a phase ratio of ≈1:2. The photoluminescence of hybrid aero-β-Ga₂O₃/ZnGa₂O₄ nanocomposite networks demonstrates narrow band (λ_em = 504 nm) green light emission of ZnGa₂O₄ under UV light excitation (λ_ex = 300 nm). The evaluation of the metal-oxide network performance for electrochemical application for Li-ion batteries shows high initial capacities of ≈714 mAh g⁻¹ at 100 mA g⁻¹ paired with exceptional rate performance even at high current densities of 4 A g⁻¹ with 347 mAh g⁻¹. This study provides is an exciting showcase example of novel networked materials and demonstrates the opportunities of tailored micro-/nanostructures for diverse applications a diversity of possible applications.     

Reprint of: Multi-scale 2D tracking of articulated objects using hierarchical spring systems

This paper presents a flexible framework to build a target-specific, part-based representation for arbitrary articulated or rigid objects. The aim is to successfully track the target object in 2D, through multiple scales and occlusions. This is realized by employing a hierarchical, iterative optimization process on the proposed representation of structure and appearance. Therefore, each rigid part of an object is described by a hierarchical spring system represented by an attributed graph pyramid. Hierarchical spring systems encode the spatial relationships of the features (attributes of the graph pyramid) describing the parts and enforce them by spring-like behavior during tracking. Articulation points connecting the parts of the object allow to transfer position information from reliable to ambiguous parts. Tracking is done in an iterative process by combining the hypotheses of simple trackers with the hypotheses extracted from the hierarchical spring systems.