Sol−Gel Processing of Au Nanoparticles in Bulk 10 B₂O₃−90 SiO₂Glass

Abstract

Bulk borosilicate glasses were prepared by the sol-gel process and doped with gold nanoparticles. First, a sol of the host glass (with nominal molar composition of 10% B 2 O 3 -90% SiO 2 ) was prepared, and then gold was introduced into the sol by means of a solution of a Au 3+ complex. The resulting gels were dried at 60 °C and then heated in air at various temperatures up to 600 °C to nucleate the gold particles and sinter the glass matrix. Various gold ligands were tested, and thiourea was found to be the most effective ligand in preventing fast gold reduction and precipitation to the gel surface during drying. A model based on the formation of insoluble gold species during drying of the gel is discussed to explain the phenomenon of gold precipitation to the sample surface. The heated gels were studied by measurements of the BET specific surface area and of the apparent density, showing the densification of the matrix during the heat treatments. UV-vis optical absorption spectroscopy was used to monitor the formation of Au nanoparticles that was effective after heating the gel at 300 °C in air. TEM studies revealed that two kinds of Au particles were present, with mean sizes of 10 and 30 nm. The smaller particles have a lattice spacing corresponding to face-centered cubic Au, whereas electron nanodiffraction patterns of the larger particles exhibit features of orthorhombic Au 3 Si.

Influence of heat treatment on the colour of Au and Ag glasses produced by the sol–gel pathway

“…Solid monolith glasses with the optical properties determined by the composition of these bimetallic particles can be obtained upon drying a silica gel containing the nanoparticles [13]. The production of coloured glasses through the sol-gel synthesis of nanoparticles has been considered as an alternative method for glass production with some advantages over the traditional process, among them are the low processing temperatures, and a better control over the optical properties of the glass material [18][19][20][21]. Au-Ag alloy nanoparticles were also synthesized in solid state inside a glassy silica film matrix through the interlayer diffusion of the Ag and Au contained in different sol-gel coating layers during the thermal treatment [22].…”

Borosilicates Obtained by Sol–Gel Method

“…S. Tamil Selvan et al (2002) prepared sol-gel-derived gold nanoclusters in silica glass for potential photonic applications. M. Epifani et al (2001) prepared bulk borosilicate glasses (with nominal molar composition of 10 % B 2 O 3 -90 % SiO 2 ) doped with gold nanoparticles by sol-gel process and found that Au particles have two patterns of existence form: face-centered cubic Au and orthorhombic Au 3 Si.…”

Self-assembled Au nanoparticles in SiO2 by ion implantation and wet oxidation

“…Among the different processing techniques [3][4][5][6][7] used in an attempt to synthesize nanoparticles of uniform size, shape, and depth distribution, ion implantation provides an attractive method of fabricating metal nanoparticles in solids due in part to the spatial controllability. However, subsequent annealing after the implantation promotes Ostwald ripening and associated particle growth, thus creating a wide size distribution of particles.…”