Ag fractals formed on top of a porous TiO₂ thin film

Abstract

This work demonstrates the formation of Ag fractals on top of a Ag:TiO2 thin film. The dendrite‐type objects emerged from a homogeneous and highly transparent Ag:TiO2 nanocomposite, via the mechanism of diffusion‐limited‐aggregation of Ag atoms, during heat‐treatment at 500 °C. A porous TiO2 matrix was also formed during this process, opening a wide range of possible applications, namely in sensing‐based ones, together with surface enhanced spectroscopies. Furthermore, fractals incorporate a wide range of shapes and spatial scales, inducing a potentially interesting optical response, over the whole visible range, presumably related with localized surface plasmon modes with very broad spectral distribution. Ag fractals on porous TiO2 matrix, emerged from a sputtered Ag:TiO2 nanocomposite thin film, after annealing at 500 °C. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)

Insight into the fabrication and perspective of dendritic Ag nanostructures

“…It is very important to control the size, shape and distribution of the Ag nanoparticles (AgNPs) to systematically investigate their antibacterial, catalytic and electro-optical properties and new applications. Numerous of synthetic routes has been developed for fabricating various Ag NPs, such as wires [8,9], rods [10,11], triangular plates [12], cubes [13][14][15], polyhedrons [16], dendrites [17,18], etc. Dendritic Ag NPs have hierarchical branches and leaves as shown in Figure 1.…”

Topological Network Properties of Fractal-Like Metallic Nanoparticle Patterns and Their Effects on Optical Resonances

“…We assume that a particle is a square with each side of 600 nm in our calculation hereafter. As shown in our previous report [26], when one fixed particle is initially set in the center of the model space, the final shape of the aggregates is a dendrite-type structure [21]. On the other hand, as shown in Figure 1, when two particles are given as initial ones, the final structures share their domains in the model space.…”

“…On the other hand, when C AgNO 3 was raised to 0.1 mol/L and s Ag increased up to ∼1400 nm, the absorption spectra were located around 11,800 nm and 14,200 nm. The absorption spectra are in a different range from that of the conventional surface plasmon resonances around the visible light range [32] and also show narrow resonance features different from the broad ones [21].…”

Development of biocompatible plasmonic thin films composed of noble metal nanoparticles embedded in a dielectric matrix to enhance Raman signals

“…Moreover, it further increased to 141 nm when the annealing temperature was 700 ˚C. These values strongly suggest that Ag crystals have diffused to the surface of the thin films, a typical behavior of this kind of films[47,60].…”