A strategy for fabrication of controllable 3D pattern containing clusters and nanoparticles inside a solid material

Laser-direct-writing of molecule-like Agmx+ nanoclusters in transparent tellurite glass for 3D volumetric optical storage

In situ constructing program-designed nanostructures via laser-direct-writing (LDW) has proved to be a reliable strategy for optical storage (OS). Herein, a kind of low-melting Ag⁺-doped TeO₂-ZnO-Na₂O (TZN) tellurite glass has been demonstrated as an ideal LDW OS medium. Microstructural and spectroscopic studies reveal the generation of molecule-like Ag_m^x+ nanoclusters featured with a broad emission band in the orange-red region upon laser irradiation. Probing the laser-glass interaction yields evidences of the spatial distribution of Ag species responsive to laser-induced thermoelastic pressure wave oscillation, as well as the heat-driven migration/aggregation of Ag species along the radial direction of the laser spot. Raman analyses disclose the loose network of TZN-glass convenient for Ag⁺ mobility and the increased network connectivity when Ag_m^x+ nanoclusters are precipitated out. Combined with the XPS result of Ag⁺ → Ag⁰ reduction, the possible formation mechanism of Ag nanoclusters stabilized in glass has been proposed. In a proof-of-concept experiment, 3D volumetric OS in the TZN glass has been demonstrated, showing optical data encoding/decoding in the form of characters and image patterns.

Tunable broadband near-infrared luminescence in glass realized by defect-engineering

Tunable broadband near-infrared (NIR)-luminescent materials play a crucial role as light sources and tunable fiber lasers in modern technologies such as high-capacity telecommunication, imaging, and remote sensing. Despite considerable effort in studying the luminescent materials doped with rare-earth or transition metal ions, it is still challenging to achieve tunable broadband emission in photonic materials, especially in glasses, for active-fiber applications. In the present work, such NIR emission is achieved by modifying oxygen-deficient structural defects (i.e., singly ionized oxygen vacancies (VO∙) in tellurium (Te)-doped germanate glass). The local glass chemistry around Te is controlled by engineering singly ionized oxygen vacancies (VO∙) in alkali-alumino-germanate glass. This enables fine-tuning of the configurations and chemical states of Te centers over a wide range of chemical states, from ionic states to neutrally charged clusters and to positively charged clusters, resulting in various intriguing luminescent behaviors (e.g., wavelength-tunable emission, great emission enhancement, bandwidth extension).

From Complex Inorganic Oxides to Ag-Bi Nanoalloy: Synthesis by Femtosecond Laser Irradiation

Bimetallic nanoalloys with a wide variety of structures and compositions have been fabricated through many diverse techniques. Generally, various steps and chemicals are involved in their fabrication. In this study, the synthesis of Ag-Bi nanoalloys by femtosecond laser irradiation of an inorganic oxide Ag₂WO₄/NaBiO₃ target without any chemicals like reducing agents or solvent is presented. The interaction between these materials and the ultrashort pulse of light allows the migration of Ag and Bi atoms from the crystal lattice to the particles surfaces and then to the plasma plume, where the reduction of the positively charged Ag and Bi species in their respective metallic species takes place. Subsequently, the controlled nucleation and growth of the Ag-Bi alloyed nanoparticles occurs in situ during the irradiation process in air. Although at the bulk level, these elements are highly immiscible, it was experimentally demonstrated that at nanoscale, the Ag-Bi nanoalloy can assume a randomly mixed structure with up to 6 ± 1 atom % of Bi solubilized into the face-centered cubic structure of Ag. Furthermore, the Ag-Bi binary system possesses high antibacterial activity against Staphylococcus aureus (methicillin-resistant and methicilin-susceptible), which is interesting for potential antimicrobial applications, consequently increasing their range of applicability. The present results provide potential insights into the structures formed by the Ag-Bi systems at the nanoscale and reveal a new processing method where complex inorganic oxides can be used as precursors for the controlled synthesis of alloyed bimetallic nanoparticles.