Reflectance properties of TiO 2 /Ag-Au nanoparticles in nanocomposite layers (original) (raw)
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Journal of Nanoparticle Research, 2014
This paper reports on the changes in the structural and morphological features occurring in a particular type of nanocomposite thin-film system, composed of Au nanoparticles (NPs) dispersed in a host TiO 2 dielectric matrix. The structural and morphological changes, promoted by in-vacuum annealing experiments of the as-deposited thin films at different temperatures (ranging from 200 to 800°C), resulted in a well-known localized surface plasmon resonance (LSPR) phenomenon, which gave rise to a set of different optical responses that can be tailored for a wide number of applications, including those for optical-based sensors. The results show that the annealing experiments enabled a gradual increase of the mean grain size of the Au NPs (from 2 to 23 nm), and changes in their distributions and separations
Functional and optical properties of Au:TiO2 nanocomposite films: The influence of thermal annealing
Applied Surface Science, 2010
A set of nanocomposite thin films consisting of Au nanoclusters dispersed in a TiO 2 dielectric matrix were deposited by reactive magnetron sputtering, and subjected to thermal annealing in vacuum, at temperatures ranging from 200 to 800 ºC. The obtained results show that the structure and the size of Au clusters, together with the matrix crystallinity, changed as a result of the annealing, and were shown to be able to change the optical properties of the films and keeping good mechanical properties, opening thus a wide number of possible applications. The crystallization of the gold nanoclusters induced by the annealing was followed by a systematic change in the overall coating behaviour, namely the appearance of Surface Plasmon Resonance (SPR) behaviour. This effect enables to tailor the thin films reflectivity, absorbance and colour coordinates, contributing for the importance of this thin film system. The different attained optical characteristics (reflectance values ranging from interference to metalliclike behaviours and colour varying for interference rainbow-like to several tones of red brownish), associated with a reasonable mechanical resistance of the coatings (good adhesion to different substrates and hardness values ranging from 5-7.5 GPa), induce the possibility to use this film system in a wide range of decorative applications.
Preparation of Plasmonic Au-TiO2 Thin Films on a Transparent Polymer Substrate
Coatings
In this work, plasmonic thin films composed of Au nanoparticles embedded in a TiO2 matrix were prepared in a transparent polymer substrate of poly(dimethylsiloxane) (PDMS). The thin films were deposited by reactive DC magnetron sputtering, and then subjected to heat treatment up to 150 °C in order to promote the growth of the Au nanoparticles throughout the TiO2 matrix. The transmittance spectrum of the thin films was monitored in situ during the heat treatment, and the minimum time required to have a defined localized surface plasmon resonance (LSPR) band was about 10 min. The average size of Au nanoparticles was estimated to be about 21 nm—the majority of them are sized in the range 10–40 nm, but also extend to larger sizes, with irregular shapes. The refractive index sensitivity of the films was estimated by using two test fluids (H2O and DMSO), and the average value reached in the assays was 37.3 ± 1.5 nm/RIU, resulting from an average shift of 5.4 ± 0.2 nm. The results show tha...
Plasmonic TiO2:Au composite layers deposited in situ by chemical spray pyrolysis
Surface and Coatings Technology, 2015
Composite TiO 2 layers with embedded Au-nanoparticles with a size of 8-20 nm were deposited in situ by chemical spray pyrolysis. EDS studies show that increase in the deposition temperature from 260 to 300°C decreases the [Au]/[Ti] ratio down to the vanishing of Au at in 400°C. The mean crystallite size of the Au-nanoparticles is slightly decreasing from 17-21 nm to 10-13 nm with increasing deposition temperature from 260 to 300°C. However, the annealing at 400°C has minor affect on the size of the Au-nanoparticles. Annealing at 400°C results in crystalline anatase TiO 2 matrix with its mean crystallite size decreasing with increasing the [Au]/[Ti] ratio in the composite layers. The total transmittance and reflectance spectra of the TiO 2 and TiO 2 :Au composite layers are complemented by the Mie calculations, showing that the red shift of the surface plasmon resonance band from 570 to 620 nm is associated with the increase in the refractive index of the TiO 2 matrix.
Nonlinear plasmonic property of Ag-nanoparticles/TiO2 composite thin films having high Ag contents
Conference on LED and Its Industrial Application
The diffuse reflectance spectra (DRS) of the fabricated Ag-nanoparticles/TiO2 composite thin films (COMP=Agn, where n is Ag-mol%) with different amount of Ag (10 ≤ n ≤ 80) and ca. 100 nm thickness were measured and analyzed by using Kubelk-Munk equation for DRS, in order to study the plasmonic effect of Ag-nanoparticles (Ag-NP) in dielectric TiO2 matrix. The DRS of the COMP-Ag10 shows the main plasmon peak at 410 nm and two very weak peaks intensities at 340 nm and 500 nm respectively. In the DRS of the composite thin films with amounts of Ag from 20 to 50 Ag-mol%, two overlapped plasmon peaks in the range from 360 to 400 nm and two to three overlapped peak in the range 2 Daniel Shipwiisho Likius, Uahengo Veikko and Rahman Ateeq from 500 nm to 700 nm appeared. On the other hand, the DRS of the COMP=Ag60 and COMP-Ag70 show three overlapped peaks in the range from 330 to 400 nm and single weak peak with lower plasmon intensity at around 500 nm and 650 nm, respectively. It was thus clarified that the peak positions at different specific lambda maximum in DSR are nonlinear to the Ag content in the composite thin films. These peaks found in DSR are due to both surface plasmon resonance (SPR) and localized surface plasmon resonance (LSPR).
Fabrication and Optical Properties of Plasmonic Nanocomposite Structures
2020 Fourteenth International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials), 2020
In this work, we demonstrate a single-step laser-assisted fabrication of thin plasmonic nanocomposite thin films. The common processes taking place in Ag:Au:TiO2 thin nanocomposite films under UV laser irradiation are discussed. We describe the main nanostructure formation mechanisms, as well as their effect on the optical properties of the films. The obtained results pave the way for the implementation of such materials in modern photonics and optoelectronics devices, photocatalytic systems, sensing, and SERS due to their unique and well-controlled optical properties.
Journal of Applied Physics, 2002
Nanocomposite thin films formed by Ag nanocrystals embedded in an amorphous aluminum oxide ͑Al 2 O 3 ͒ host were prepared by alternating-target pulsed laser deposition. Spectroscopic ellipsometry was used to determine the effective refractive index ͑nϭnϩik). When the Ag volume fraction is over 2%, the linear optical properties of the nanocomposite films differ from those of the pure dielectric host. The extinction coefficient shows a maximum around 435 nm that is related to the surface plasmon resonance. Near this wavelength, the real part of the refractive index undergoes anomalous dispersion, leading to a significant increase of the n value of the composite compared to that of the matrix.
Pure and Applied Chemical Sciences, 2018
The diffuse reflectance spectra (DRS) of the fabricated Ag-nanoparticles/TiO2 composite thin films (COMP=Agn, where n is Ag-mol%) with different amount of Ag (10 ≤ n ≤ 80) and ca. 100 nm thickness were measured and analyzed by using Kubelk-Munk equation for DRS, in order to study the plasmonic effect of Ag-nanoparticles (Ag-NP) in dielectric TiO2 matrix. The DRS of the COMP-Ag10 shows the main plasmon peak at 410 nm and two very weak peaks intensities at 340 nm and 500 nm respectively. In the DRS of the composite thin films with amounts of Ag from 20 to 50 Ag-mol%, two overlapped plasmon peaks in the range from 360 to 400 nm and two to three overlapped peak in the range 2 Daniel Shipwiisho Likius, Uahengo Veikko and Rahman Ateeq from 500 nm to 700 nm appeared. On the other hand, the DRS of the COMP=Ag60 and COMP-Ag70 show three overlapped peaks in the range from 330 to 400 nm and single weak peak with lower plasmon intensity at around 500 nm and 650 nm, respectively. It was thus clarified that the peak positions at different specific lambda maximum in DSR are nonlinear to the Ag content in the composite thin films. These peaks found in DSR are due to both surface plasmon resonance (SPR) and localized surface plasmon resonance (LSPR).
Journal of Alloys and Compounds, 2019
Thin films of Ag-TiO 2 plasmonic nanocomposites were fabricated on silica glass substrates by a combined approach using thermal evaporation and RF magnetron sputtering. The optical and plasmonic response of Ag-TiO 2 nanocomposites were tuned with the help of thermal annealing by varying the annealing temperature from 400 o C to 600 o C. The optical absorption spectra revealed the transformation of Ag nanolayer into Ag nanoparticles upon annealing. The band gap of Ag-TiO 2 nanocomposite thin films varied from 3.09 eV to 2.53 eV due to annealing. AFM studies revealed growth of nanostructures in the Ag-TiO 2 nanocomposites with increase in annealing temperature. The average nanoparticle size varied from 27 nm to 230 nm upon annealing. XRD results confirmed the appearance of Ag nanoparticles along with nanostructured anatase TiO 2. The photoluminescence spectra of Ag-TiO 2 nanocomposites revealed significant enhancement in intensity of UV and defect emissions with increasing annealing temperature. The observed enhancement originated due to the changes in the plasmonic properties of Ag nanostructures in the nanocomposites upon annealing. The tentative mechanism of enhancement in photoluminescence of Ag-TiO 2 nanocomposite upon thermal annealing is discussed.