H2-induced copper and silver nanoparticle precipitation inside sol-gel silica optical fiber preforms

Abstract

Ionic copper- or silver-doped dense silica rods have been prepared by sintering sol-gel porous silica xerogels doped with ionic precursors. The precipitation of Cu or Ag nanoparticles was achieved by heat treatment under hydrogen followed by annealing under air atmosphere. The surface plasmon resonance bands of copper and silver nanoparticles have been clearly observed in the absorption spectra. The spectral positions of these bands were found to depend slightly on the particle size, which could be tuned by varying the annealing conditions. Hence, transmission electron microscopy showed the formation of spherical copper nanoparticles with diameters in the range of 3.3 to 5.6 nm. On the other hand, in the case of silver, both spherical nanoparticles with diameters in the range of 3 to 6 nm and nano-rods were obtained.

Influence of gamma-ray irradiation on Faraday effect of Cu-doped germano-silicate optical fiber

“…The measured absorption spectra also represented that the strong absorption bands of the Cu-related defect centers were located centering at VIS and UV region with an extension up to near infrared (NIR) region. In addition to the overall increase of optical absorption, distinct absorption bands peaking at 565 nm, 585 nm were also found to appear after the irradiation, and they are identical to the surface plasmon resonance (SPR) absorption of Cu metal particles in the previous reports [16][17][18]24]. Thus Cu 2+ ions in the optical fiber core were thought to be converted to Cu metal particles by the irradiation as following reduction reaction: Cu 2+ + 2e À = Cu.…”

“…And we have found that the Cu ions are involved in the formation of radiation-induced defect centers in the optical fiber that affect the magneto-optical properties. Moreover, a number of studies have also shown that Cu ions in silicate glasses were reduced to those with lower valences by the thermal treatment, the gamma-ray irradiation, and the ion-exchange techniques, which contributed to the change in magneto-optical properties of the glasses [14][15][16][17][18]. Therefore, we have chosen Cu-doped germano-silicate optical fiber to investigate the influence of gamma-ray irradiation on magneto-optical properties, particularly on Faraday effect.…”

Analysis of Localized Surface Plasmon Resonance in Ag/ITO/CdS/SiO2 Multilayered Nanostructured Composite

“…However, the peak at 260 nm blue-shifts slightly due to the electronic transition of the Ag þ ions thus producing absorption bands at 200 nm and 230 nm, whereas the electronic transition of metallic Ag 0 appears in the spectral range between 250 nm and 330 nm. [25][26][27] Figure 2 shows that there are three plasmonic resonance peaks in the extinction spectrum for a surrounding medium with a refractive index of 1.52, dipole resonance of 740 nm, quadrupole resonance of 570 nm and octupole resonance of 340 nm. Similar results have been obtained from a tunable plasmonic nanoparticle consisting of a metallic silver shell and dielectric SiO 2 core.…”

Recent advances in sol–gel synthesis of monolithic silica and silica-based glasses

“…Highpressure H 2 loading below 100 • C followed by thermal annealing in air enables the homogeneous precipitation of Ag and Cu nanoparticles in sol-gel-derived silica rods (Fig. 13) [167]. Silica glasses containing fluoride nanoparticles will be described separately in Section 4.3.…”

“…A quantitative analysis using the lanthanum-alizarin complexone method indicates that nearly all the fluorine atoms are bound to Reprinted with permission from Ref. [167]; Copyright 2012 Springer. the silica phase of the HF-catalyzed gels prepared from a solution with a TEOS:EtOH:H 2 O:HF molar ratio of 1:4:5:0.1 [176].…”