Instability of Ag nanoparticles in SiO₂at ambient conditions

Abstract

Abstract. The room temperature stability of nanometer-sized silver clusters in silica matrices has been investigated by following the temporal evolution of their surface plasmon absorption. Ag clusters in SiO 2 were prepared by either annealing silica samples doped with atomic silver or by co-deposition of pre-formed clusters of defined size. Clusters were found to be unstable at ambient conditions on a time scale of days to weeks, independent of preparation conditions. The disappearance of the plasmonic resonance is explained by successive oxidation of the clusters even inside the matrix.

Kinetics of Ag nanoparticle growth in thick SiO2 films: An in situ optical assessment of Ostwald ripening

“…This implies a greater quantity of NPs with larger sizes and thus stability which would in turn oppose dissolution during ripening and as a consequence, E R,N > E D,N is possible. On the contrary, the air atmosphere promotes the occurrence of rather unstable particles owing to O 2 diffusion within the silica matrix [23]. Accordingly, during HT in the presence of O 2 , a greater quantity of NPs with smaller sizes and thus instability [22,23] would be attained which in turn would favor thermodynamically the particle dissolution during ripening, and as a consequence, E R,A < E D,A may result.…”

Ion irradiation synthesis of Ag–Au bimetallic nanospheroids in SiO2 glass substrate with tunable surface plasmon resonance frequency

“…In general, the Ag nanostructures are unstable and easily get oxidized. [39][40][41] Therefore, the as-deposited samples were kept in the vacuum condition. However, a strong increase in the oxidation resistance was observed with the increase of Au atomic fraction inside the nanostructures, 41 and it is reported that most of the Au-Ag nanostructures was not oxidized at gold fractions above 0.4 in solution.…”

“…Therefore, a layer of oxide Ag (usually Ag 2 O) was formed on the nanospheroids surface, and the Ag-core Ag-oxide shell structure will induce a red shift of the characteristic surface plasmon resonance response for pure Ag, which located at around 400 nm. 39,40 However, this plasmon absorption peak was rather stable over time: after 8 months in a low vacuum condition, the plasmon absorption intensity has decreased a little (see S1 in the supplementary information 47 ).…”

Antibacterial Action and Physicochemical Properties of Stabilized Silver and Gold Nanostructures on the Surface of Disperse Silica

“…These films were bright colored, transparent, stable and had characteristic SPR bands belonging to Ag or Au NPs. However, Ag clusters formed on disperse silica surface were found to be stable only for a few days [3]. The self-agglomeration and oxidation of Ag NPs were detected also within the porous silica films [12].…”

“…That is why developed silica surface covered with OH groups offers unique environment for the fixation and stabilization of nanosized silver and gold particles (Ag and Au NPs) for applications in optics, sensing, catalysis and as bactericides. However, Ag NPs are unstable on silica surface under ambient conditions due to fast oxidation [3]. It is important to prevent or inhibit the aggregation of NPs and oxidation process at the nanocluster formation stage, especially in case of silver.…”