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Investigation of thermal conductivity property of plasmonic nanofluids based on gold nanorods prepared by seed-mediated growth method

Mohammadzadeh Mahsa, Ashjari Mohsen, Zare Davoud

Technical Sciences / University of Warmia and Mazury in Olsztyn

2019

nr 22(2)

119--133

In this paper, nanofluids were prepared based on gold nanorods in basic fluid, water, by single-stage chemical reduction and in different volume fractions and the used gold nanorods were synthesized by seed-mediated growth method in different dimensional ratios. The properties of the prepared nanoparticles, including crystalline size, aspect ratio, surface properties, nanoparticle purity, shape and morphology of nanostructures were investigated using x-ray diffraction, UV-vis spectroscopy, FT-IR, and transmitted electron microscopy. The effect of changing parameters of Nano rod dimensions, changes in Nano rod volume fraction in water and also the effect of temperature on the nanofluid thermal conductivity coefficient were investigated using transient hot wire method. The results showed that reducing the aspect ratio, increasing the volume fraction and increasing the temperature increase the thermal conductivity. In fact, results show that an increase in the nanorods aspect ratio with a constant volume fraction of 1:50 of gold in water nanorod and at room temperature leads to a decrease in the thermal conductivity of the nanofluid. Also, increasing the two parameters of volume fraction and temperature significantly increases the thermal conductivity coefficient.

Compositional arrangement of rod/shell nanoparticles: an approach to provide efficient plasmon waveguides

Ahmadivand A., Golmohammadi S.

Opto-Electronics Review

2014

Vol. 22, No. 2

101-108

In this work, we investigated the optical properties of a novel compositional configuration of gold nanorod and silver nanoshell which is embedded in a SiO₂ substance. The proper geometrical sizes for compositional rod/shell arrangement have been obtained based on the position and peak of plasmon resonance at λ~1550 nm. Adjusting the plasmon resonance position at declared spectrum helps us to provide an arrangement which shows high efficiency and minimum losses. The influence of destructive components such as internal damping and scattering on the rod/shell combination is demonstrated by corresponding diagrams. Moreover, we proposed a nano-array based on examined configuration and the quality of light transmission along the array is studied. We figured out and depicted optical properties of the array such as transmission loss factors, group velocities, transmitted power, transmission quality, and two-dimensional snapshots of surface plasmons (Sps) coupling between nanoparticles arrangements under transverse and longitudinal modes excitations. Ultimately, it is shown that the suggested nanostructure based on studied nanoparticles configuration has a potential to utilize in designing nanophotonic devices such as splitters, couplers, and routers. Finite-difference time-domain method (FDTD) as a major simulation model has been employed to study the features of the waveguide.