Evolution of silver in a eutectic-based Bi2O3–Ag metamaterial

Abstract

The development of novel manufacturing techniques of nano-/micromaterials, especially metallodielectric materials, has enabled dynamic development of such fields as nanoplasmonics. However, the fabrication methods are still mostly based on time-consuming and costly top-down techniques limited to two-dimensional materials. Recently, directional solidification has been proposed and utilized for manufacturing of volumetric nanoplasmonic materials using the example of a Bi 2 O 3 -Ag eutectic-based nanocomposite. Here, we explain the evolution of silver in this composite, from the crystal growth through the post-growth annealing processes. Investigation with tunneling electron microscopy shows that silver initially enters the composite as an amorphous AgBiO 3 phase, which is formed as a wetting layer between the grains of Bi 2 O 3 primary phase. The post-growth annealing leads to decomposition of the amorphous phase into Bi 2 O 3 nanocrystals and intergranular Ag nanoparticles, providing the tunable localized surface plasmon resonance at yellow light wavelengths.

Selective surface-enhanced Raman scattering in a bulk nanoplasmonic Bi2O3-Ag eutectic composite

“…These new features could result from another polymorph of Bi 2 O 3 . This is in agreement with the transmission electron microscopy (TEM) measurements [28] which demonstrated another polymorph: γ-Bi 2 O 3 nanocrystals in the areas containing Ag precipitates. The spectroscopic distinction between the alpha and gamma polymorphs is ambiguous, given the overlapping of their bands up to 550 cm −1 ; however, at larger wavenumbers, characteristic bands of γ-Bi 2 O 3 are apparent, assigned to stretching vibrations in tetrahedral BiO 4 units.…”

“…Concentration of γ-Bi 2 O 3 nanocrystals in the precipitates was assessed based on high-resolution transmission electron microscopy (HRTEM) dark field images [28]. The area showing the precipitates was selected and the number of bright pixels representing γ-Bi 2 O 3 crystals was divided by the total number of pixels.…”

“…Earlier studies have identified this material to be made up of two separate phases. The structure consists of a matrix of α-Bi 2 O 3 grains separated by an amorphous phase of precipitates containing Ag, Bi and O [28]. Post-growth heat treatment transforms this non-crystalline phase to a phase containing Ag and Bi NPs, as well as γ-Bi 2 O 3 nanocrystals.…”

Durability of SrTiO3–TiO2 eutectic composite as a photoanode for photoelectrochemical water splitting

“…The grown rod was 120 mm long with a 3 mm diameter. The μ-PD has been demonstrated to be a useful technique for quick material growth, and has been shown to enable fabrication of materials that find applications in various fields: optoelectronics; 28,29 photonic crystals; 30–32 metamaterials; 33–36 THz materials; 37,38 and SERS detection. 39,40 X-ray powder diffraction (XRD) qualitative phase analysis of the SrTiO 3 –TiO 2 eutectic composite was performed on the as-grown samples using a Rigaku SmartLab 3 kW diffractometer.…”