scholarly journals Nurturing Plasmonic Properties of Nanocomposite Thin Films: The Importance of Optimum Oblate Shape

2021 ◽  
Vol 10 (2) ◽  
pp. 73-82
Author(s):  
Ranjit Laha
Keyword(s):  
Thin Films ◽  
Volume Fraction ◽  
Resonance Condition ◽  
Positive Root ◽  
Quadratic Equation ◽  
Oblate Shape ◽  
Nanocomposite Thin Films ◽  
Lower Volume ◽  
Visible Wavelengths ◽  
First Time

Metal nanoparticles (MNPs) embedded dielectric thin films are very crucial for many optoelectronic applications. This report investigates various ways of tuning the plasmonic properties of such nanocomposite thin films. For this, the well-known plasmon resonance condition was first generalized to include the shape and volume fraction of MNPs. This was followed by deriving an empirical formula for the resonance position (λR) which was worked out to be the positive root of a quadratic equation. The coefficients of the deduced quadratic relation involve the parameters obtained from the empirical fit to some of the experimental dielectric functions of MNPs available in literature. The derived working formula enables research community to tune the LSPR of nanocomposites in the whole range of visible wavelengths. The derived formula also concluded that with known lower volume fractions, shape of MNPs affects λR the most, compared to the other parameters. The derived formula was validated by calculating the full extinction spectra. It was shown for the first time that there exists an optimum value of oblate shape to give maximum resonance for a given nanocomposite.

Optical Properties of Nanocomposite Thin-Films

2006 ◽  
Author(s):  
Anna Garahan ◽  
Laurent Pilon ◽  
Juan Yin ◽  
Indu Saxena
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Maxwell’S Equations ◽  
Maxwell's Equations ◽  
Volume Fraction ◽  
Effective Index ◽  
Absorption Index ◽  
Index Of Refraction ◽  
Nanocomposite Thin Films ◽  
Effective Index Of Refraction

This paper aims at developing numerically validated models for predicting the through-plane effective index of refraction and absorption index of nanocomposite thin-films. First, models for the effective optical properties are derived from previously reported analysis applying the volume averaging theory (VAT) to the Maxwell's equations. The transmittance and reflectance of nanoporous thin-films are computed by solving the Maxwell's equations and the associated boundary conditions at all interfaces using finite element methods. The effective optical properties of the films are retrieved by minimizing the root mean square of the relative errors between the computed and theoretical transmittance and reflectance. Nanoporous thin-films made of SiO2 and TiO2 consisting of cylindrical nanopores and nanowires are investigated for different diameters and various porosities. Similarly, electromagnetic wave transport through dielectric medium with embedded metallic nanowires are simulated. Numerical results are compared with predictions from widely used effective property models including (1) Maxwell-Garnett Theory, (2) Bruggeman effective medium approximation, (3) parallel, (4) series, (5) Lorentz-Lorenz, and (6) VAT models. Very good agreement is found with the VAT model for both the effective index of refraction and absorption index. Finally, the effect of volume fraction on the effective complex index of refraction predicted by the VAT model is discussed. For certain values of wavelengths and volume fractions, the effective index of refraction or absorption index of the composite material can be smaller than that of both the continuous and dispersed phases. These results indicate guidelines for designing nanocomposite optical materials.

Size-controlled growth and antibacterial mechanism for Cu:C nanocomposite thin films

2017 ◽  
Vol 19 (1) ◽  
pp. 237-244 ◽  
Author(s):  
Amjed Javid ◽  
Manish Kumar ◽  
Seokyoung Yoon ◽  
Jung Heon Lee ◽  
Jeon Geon Han
Keyword(s):  
Thin Films ◽  
Antibacterial Activity ◽  
Volume Fraction ◽  
Size Reduction ◽  
Antibacterial Mechanism ◽  
Cu Nanoparticles ◽  
Plasma Energy ◽  
Fixed Volume ◽  
Nanocomposite Thin Films ◽  
Size Controlled

Plasma energy induced size reduction of Cu nanoparticles (at fixed volume fraction) in C matrix demonstrated effective antibacterial activity.

Nanomechanical Properties of UV Degraded TiO2/Epoxy Nanocomposites

2004 ◽  
Vol 841 ◽  
Author(s):  
Stephanie Scierka ◽  
Peter L. Drzal ◽  
Amanda L. Forster ◽  
Stephanie Svetlik
Keyword(s):  
Thin Films ◽  
Volume Fraction ◽  
Surface Region ◽  
Chemical Oxidation ◽  
Nanocomposite Films ◽  
Attenuated Total Reflectance ◽  
Integrating Sphere ◽  
Scanning Calorimetry ◽  
Nanocomposite Thin Films ◽  
Instrumental Indentation

ABSTRACTModel epoxy nanocomposite thin films containing one of three types of titanium dioxide (TiO2) particles were degraded using an integrating sphere-based ultraviolet weathering chamber. Instrumental Indentation Testing (IIT) was used to measure nanomechanical changes in the surface region of thin films resulting from UV exposure. Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Differential Scanning Calorimetry (DSC) were used to support the mechanical results with chemical and thermal data. The unfilled epoxy was the most photosensitive sample tested, exhibiting the highest rates of chemical oxidation, the largest decrease in the glass transition (Tg), and the greatest increase in elastic modulus with increased exposure. Similar trends were observed in the nanocomposite films, but the rates of change were much lower than the unfilled epoxy and decreased with increasing volume fraction of nanoparticles.

The Effect of Nanoparticles on the Thermal Conductivity of Crystalline Thin Films at Low Temperatures

2007 ◽  
Author(s):  
Kamal M. Katika ◽  
Laurent Pilon
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Radiative Transfer ◽  
Film Thickness ◽  
Volume Fraction ◽  
Phonon Transport ◽  
Solid Matrix ◽  
Discrete Ordinates ◽  
Nanoparticle Radius ◽  
Nanocomposite Thin Films

This study is concerned with the prediction of the effective thermal conductivity of nanocomposite thin films consisting of nanoparticles randomly distributed in a solid matrix. Crystalline sodium chloride with embedded monodisperse silver nanoparticles is investigated as a case study for thin films where phonons are the main heat carriers. To the best of our knowledge, the equation for phonon radiative transfer is solved for the first time with an exact scattering transport cross-section of the nanoparticles as a function of frequency which was obtained from the literature. The one-dimensional equation for phonon radiative transfer based on the isotropic scaling approximation is solved on a spectral basis using the discrete ordinates method to predict the temperature profile and the heat flux across the nanocomposite thin films. The thermal conductivity is retrieved at temperatures where the effects of Umklapp and Normal processes can be neglected and scattering by the particles on phonon transport dominates. The method of solution and closure laws were validated with experimental data of thermal conductivity for bulk samples at 2.53, 5.94, and 10.56 K. The effects of the film thickness (1 μm to 2.5 cm), nanoparticle diameter (5 nm to 100 nm) and volume fraction (0.0001 to 0.2) on the thermal conductivity of the nanocomposite thin film are investigated. The results indicate that the thermal conductivity decreases with decreasing particle radius as well as with increasing particle concentration. Finally, a dimensionless analysis revealed a power law relationship between the dimensionless thermal conductivity and a dimensionless length of the order of the acoustic thickness of the medium. These results can be used to design nanocomposite thin films for various low temperature thermal applications by choosing optimal nanoparticle radius and volume fraction, and film thickness.

High performance polymer/BaTiO3 nanocomposites based on surface-modified metal oxide nanoparticles using functional phosphonic acids for electronic applications

2008 ◽  
Vol 1113 ◽  
Author(s):  
Philseok Kim ◽  
Natalie M. Doss ◽  
John P. Tillotson ◽  
Xiao-Hong Zhang ◽  
Simon C. Jones ◽  
...  
Keyword(s):  
Thin Films ◽  
Surface Modification ◽  
Metal Oxide ◽  
Phosphonic Acid ◽  
Volume Fraction ◽  
Metal Oxide Nanoparticles ◽  
Dielectric Strength ◽  
Oxide Nanoparticles ◽  
High Quality ◽  
Nanocomposite Thin Films

ABSTRACTPolymer/ceramic nanocomposites provide a means of combining the high permittivities (εr) of metal oxide nanoparticles with the solution-processability and high dielectric strength of polymeric hosts. Simple mixing of nanoparticles and polymers generally results in poor quality nanocomposites due to the agglomeration of nanoparticles and poor miscibility of nanoparticles with host materials. We have shown that surface modification of metal oxide nanoparticles with phosphonic acid-based ligands affords robust surface modification and improves the processiblity and the quality of the resulting nanocomposites. We report on the use of phosphonic-acid modified barium titanate (BaTiO3, BT) nanoparticles in dielectric nanocomposites and their applications to high-energy-density capacitors and solution-processable high permittivity gate insulators in organic field-effect transistors (OFETs). Surface modification of BT nanoparticles enabled the formation of high quality nanocomposite thin films with ferroelectric polymer hosts such as poly(vinylidene fluoride-co-hexafluoropropylene), P(VDF-HFP), with large volume fractions (up to 50 vol. %), which are potentially useful materials for electrical energy storage. Similarly, the use of phosphonic acid-modified BT nanoparticles in cross-linked poly(4-vinylphenol) (PVP) allowed to form gate insulators for OFETs. High quality nanocomposite thin films at high nanoparticle volume fractions (up to 37 vol. %) with a large capacitance density (∼50 nF/cm2) and a low leakage current (10−8 A/cm2) were obtained. Pentacene-based p-type OFETs using these nanocomposites showed a large on/off current ratio (Ion/off 104 ∼ 106). We will also present the results from a recent experimental and theoretical study where the BT nanoparticle volume fraction was systematically varied in P(VDF-HFP) host, εr = 11, to find the optimum permittivity and dielectric strength, which provided a guideline for the optimization of the volume fraction for achieving maximum energy density.

Phase configuration, nanostructure, and mechanical behaviors in Ti-B-C-N thin films

2009 ◽  
Vol 24 (8) ◽  
pp. 2520-2527 ◽  
Author(s):  
Yonghao Lu ◽  
Junping Wang ◽  
Yaogen Shen ◽  
Dongbai Sun
Keyword(s):  
Thin Films ◽  
Photoelectron Spectroscopy ◽  
Solid Solution Hardening ◽  
Mechanical Behaviors ◽  
Additional Increase ◽  
N Content ◽  
X Ray ◽  
Nanocomposite Thin Films ◽  
The Cost ◽  
Nano Grains

A series of Ti-B-C-N thin films were deposited on Si (100) at 500 °C by incorporation of different amounts of N into Ti-B-C using reactive unbalanced dc magnetron sputtering in an Ar-N2 gas mixture. The effect of N content on phase configuration, nanostructure evolution, and mechanical behaviors was studied by x-ray diffraction, x-ray photoelectron spectroscopy, Raman spectroscopy, high-resolution transmission electron microscopy, and microindentation. It was found that the pure Ti-B-C was two-phased quasi-amorphous thin films comprising TiCx and TiB2. Incorporation of a small amount of N not only dissolved into TiCx but also promoted growth of TiCx nano-grains. As a result, nanocomposite thin films of nanocrystalline (nc-) TiCx(Ny) (x + y < 1) embedded into amorphous (a-) TiB2 were observed until nitrogen fully filled all carbon vacancy lattice (at that time x + y = 1). Additional increase of N content promoted formation of a-BN at the cost of TiB2, which produced nanocomposite thin films of nc-Ti(Cx,N1-x) embedded into a-(TiB2, BN). Formation of BN also decreased nanocrystalline size. Both microhardness and elastic modulus values were increased with an increase of N content and got their maximums at nanocomposite thin films consisting of nc-Ti(Cx,N1-x) and a-TiB2. Both values were decreased after formation of BN. Residual compressive stress value was successively decreased with an increase of N content. Enhancement of hardness was attributed to formation of nanocomposite structure and solid solution hardening.

scholarly journals Mechanochemical Synthesis and Nitrogenation of the Nd1.1Fe10CoTi Alloy for Permanent Magnet

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3854
Author(s):  
Hugo Martínez Sánchez ◽  
George Hadjipanayis ◽  
Germán Antonio Pérez Alcázar ◽  
Ligia Edith Zamora Alfonso ◽  
Juan Sebastián Trujillo Hernández
Keyword(s):  
Mechanochemical Synthesis ◽  
Applied Field ◽  
Volume Fraction ◽  
Synthesis Method ◽  
High Energy ◽  
Direction Parallel ◽  
Best Value ◽  
Heat Treated ◽  
Bcc Phase ◽  
First Time

In this work, the mechanochemical synthesis method was used for the first time to produce powders of the nanocrystalline Nd1.1Fe10CoTi compound from Nd2O3, Fe2O3, Co and TiO2. High-energy-milled powders were heat treated at 1000 °C for 10 min to obtain the ThMn12-type structure. Volume fraction of the 1:12 phase was found to be as high as 95.7% with 4.3% of a bcc phase also present. The nitrogenation process of the sample was carried out at 350 °C during 3, 6, 9 and 12 h using a static pressure of 80 kPa of N2. The magnetic properties Mr, µ0Hc, and (BH)max were enhanced after nitrogenation, despite finding some residual nitrogen-free 1:12 phase. The magnetic values of a nitrogenated sample after 3 h were Mr = 75 Am2 kg–1, µ0Hc = 0.500 T and (BH)max = 58 kJ·m–3. Samples were aligned under an applied field of 2 T after washing and were measured in a direction parallel to the applied field. The best value of (BH)max~114 kJ·m–3 was obtained for 3 h and the highest µ0Hc = 0.518 T for 6 h nitrogenation. SEM characterization revealed that the particles have a mean particle size around 360 nm and a rounded shape.

scholarly journals Growth of heterolayered [cubic-TaC(111) + rhombohedral-Ta3C2(0001)] nanocomposite thin films on Al2O3(0001)

2021 ◽  
Vol 204 ◽  
pp. 116499
Author(s):  
Koichi Tanaka ◽  
Michael E. Liao ◽  
Angel Aleman ◽  
Hicham Zaid ◽  
Mark S. Goorsky ◽  
...  
Keyword(s):  
Thin Films ◽  
Nanocomposite Thin Films
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