Polyethylene oxide‐poly(3,4‐ethylenedioxythiophene) (PEO‐PEDOT) nanocomposite films ‐ incorporated with NiZnFeO4 nanoparticles (NPs) were deposited using a dip‐coating technique. X‐ray diffraction ...(XRD) analysis revealed peaks at 35.4, 43.2, 54.5, and 56.3° diffraction angles, corresponding to NiZnFeO4NPs diffraction planes of 311, 400, 422, and 511, respectively. The PEO‐PEDOT film exhibited a smooth amorphous nature with a sheet nanostructure behavior. The incorporation of NiZnFeO4NPs NPs into the PEO‐PEDOT nanocomposite films led to an increase in surface roughness and thermal stability. The nanocomposite films also exhibited sheet nanostructure behavior as observed by SEM micrographs. The bandgap energies of the films, as deduced from the Tauc plot, exhibited a monotonic decrease from 3.91 to 3.60 eV as the NiZnFeO4NPs concentration increased from 0 to 8 wt%. A mathematical model was formulated to predict the bandgap energies versus NiZnFeO4NPs concentration. Additionally, the electrical conductivity of the nanocomposite films increased monotonically from 0.46 to 1.30 mS cm−1 as the NiZnFeO4NPs concentration increased from 0 to 8 wt%, as determined by 4‐point probe. The observed correlation between the optical and electrical properties of the nanocomposite films indicates promising prospects for utilizing these materials in optoelectronic devices.
Characterizations of PEO‐PEDOT/NiZnFeO4 NPs nanocomposite films.
We synthesize and optically characterize pure PMMA and PMMA incorporated with metal oxides nanoparticles (MO NPs) such as ZnO, CuO, TiO2 and SiO2 NPs nanocomposite thin films with weight ...concentration of 10% using dip-coating technique. SEM images of MO NPs show that all NPs have nearly an average size of around 50 nm. The optical parameters such as, optical parameters (n and k), optoelectronics properties, dispersion, band-gap energy and band structure of as-prepared nanocomposite thin films were determined by analyzing the transmittance and reflectance spectra. Mainly, optical band-gap energy (Eg) and the thickness of thin films are evaluated to a high degree of accuracy by utilizing Q-functional derived using a mathematical model recently published. The Q(E) is a functional containing experimental transmission and reflection data and the incident photon energy. The Eg value of un-doped PMMA thin films is found to be 4.273 eV. This value decreases as pre-selected MO NPs are introduced into thin films. These values are in excellent agreement with those determined using Tauc method. The FTIR technique is employed to elucidate the vibrational bands of the nanocomposites and the intermolecular bonding between PMMA matrix and the MOs NPs. Thermal stability is investigated by employing thermogravimetric analysis (TGA) at temperatures up to 400 °C. The obtained TGA thermograms indicate that adding MOs NPs to PMMA yield thin films of better thermal stability. The obtained doped thin films show a great promise for fabricating high-efficient optoelectronic devices.
Polymethyl methacrylate (PMMA); metal oxides nanoparticles (MO NPs); zinc oxide (ZnO); copper oxide (CuO); silicon dioxide (SiO2); Titanium dioxide (TiO2); optical properties; bandgap energy; FTIR; TGA
The experimental and ab initio results on structural, optical, and electronic properties of Zn(OH)2 and ZnO thin films (TFs) at various annealing temperatures are reported. The as-grown TF consists ...of Zn(OH)2 while annealing them at temperatures higher than 300 °C yields high-quality ZnO. The films were highly crystallized in a hexagonal structure with (200) orientation by XRD analysis. The evaluated optical band gap energies of Zn(OH)2 and ZnO TFs were 3.955 and 3.286 eV, respectively, and agree well with Vienna ab initio hybrid functional HSE06 density of states calculations. The material activation of ZnO and Zn(OH)2 TFs in electrochemical degradation catalyses of methyl red in water proven that ZnO TFs have higher decolourization efficiency than Zn(OH)2 TFs. The electrochemical circuit used was performed under experimental conditions of 12 V voltage difference and 0.3 A current.
•Zinc oxide and zinc hydroxide thin films are interrelated with the role of hydrogen and hydroxide in ZnO.•Zn(OH)2 coating is usually used as a galvanic coating to prevent corrosion of metal substrates.•ZnO and Zn(OH)2 thin films activation performed in electrochemical degradation catalyzed Methyl red (MR) in water.•ZnO thin film has higher decolourization efficiency compared to that of Zn(OH)2 thin film.•The experimental and the computational ab intio hybrid functional HSE06 density of states of bandgap energies are comparable.
The coupling behavior of the wide field surface plasmon microscopy (WF-SPRM) with single-, two-, and multiple-gold nanoparticles (AuNPs) with different AuNPs sizes is investigated using theoretical, ...simulation, and experimental approaches. The signal intensity of a single AuNP increases from 208 a.u. to 583 a.u. as particle size increases from 40 to 80 nm, which evidences the signal-building mechanism of Rayleigh scattering theory. A discrete particle model of SPR is used to understand the interaction between an Au-layer and a single AuNP. The calculated intensity profile of the single AuNP from the discrete particle model is accepted with the experimental data. In addition, the superposition between 2-AuNPs surface plasmon waves is studied using the finite element method as well as experimental data from WF-SPRM. The surface plasmon waves around the two particles generate an interference pattern. Finally, it is demonstrated that plasmonic multiple particles scattering can be represented by an effective media, which is described by Maxwell-Garnet equations.
A well-prepared ZnO and (Cd–Ni) co-doped ZnO thin films are synthesized using the simple, inexpensive sol–gel method by immersing technique. The optical, structural, and morphological ...characterizations of (Cd–Ni) co-doped ZnO thin films are performed by employing UV–Vis spectrophotometry, X-ray diffraction (XRD), and the scanning electron microscope (SEM). The XRD patterns are consistent with those for standard hexagonal wurtzite structure. As the content of (Cd–Ni) co-dopant is increased from 0 to 8%, the transmittance spectra (
T
%
) of thin films is decreased from 89 to 53%. In contrast, the reflectance spectra (
R
%
) is increase from 7.8 to 18.2%. The values of the optical band gap
E
g
are found between 3.09 and 3.28 eV depending on the (Cd–Ni) co-doping ratio. A combination of Wemple–DiDomenico, Sellmeier, Spitzer-Fan models as well Drude model are implemented to estimate different optical parameters such as dispersion energy (
E
d
), zero-frequency refractive index (
n
0
), Zero-frequency dielectric constant (ε
0
), the optical moment, High-frequency dielectric (
ε
∞
), the density of state (
N
c
/m
*
), Relaxation time (τ) as well the optical mobility (
µ
opt
) and resistivity (
ρ
opt
). Technological constraints in fabricating (Cd–Ni) co-doped ZnO thin films include the variation of their properties as a function of deposition conditions such as doping concentration, nature and temperature of the substrate, technique of deposition and the nature of the chemical precursor used to control, in principle, the phase deposited and its morphology. ZnO thin films doped by transition metals have a lot of applications in optoelectronic devices such as solar cells, flat panel displays, photodetectors, gas sensors, and spintronics. Our comprehensive study paves the way to fabricate scaled devices based on (Cd–Ni) co-doped ZnO thin films.
Imaging wide-field surface plasmon resonance (SPR) microscopy sensors based on polyacrylic acid polyelectrolyte brushes (PAA PEBs) were designed to enhance the sensitivity of nano-object detection. ...The switching behavior of the PAA PEBs against changes in the pH values was investigated by analyzing the chemical, morphological, optical, and electrical properties. At pH ~1, the brushes collapse on the surface with the dominance of carboxylic groups (COOH). Upon the increase in the pH to nine, the switching process completes, and the brushes swell from dissociating most of the COOH groups and converting them into COO- groups. The domination of the negatively charged COO- groups increases the electrostatic repulsion in the polymer chains and stretches the brushes. The sensitivity of the SPR sensing device was investigated using a theoretical approach, as well as experimental measurements. The signal-to-noise ratio for a Au layer increases from six to eighteen after coating with PAA PEBs. In addition, the linewidth of the recorded image decreases from six pixels to five pixels by using the Au-PAA layers, which results from the enhanced spatial resolution of the recorded images. Coating a Au-layer with PAA PEBs enhances the sensitivity of the SPR sensing device, and improves the spatial resolution of the recorded image.
PMMA polymer doped by multi-walled carbon nanotubes (MWCNTs) has attracted much attention as promising materials for photovoltaic and optoelectronic applications. The undoped poly(methyl ...methacrylate) (PMMA) and PMMA/MWCNTs nanocomposite films doped with varying concentrations of Zirconium dioxide nanoparticles (ZrO
2
NPs) are synthesized using the casting method. It is found that the transmittance (
T
%
) decreases significantly as wt% = 5% of MWCNTs is injected into PMMA matrix. In addition, increasing the concentration of ZrO
2
NPs into PMMA- MWCNTs nanocomposite thin films results in a further reduction of the transmittance and a further increase of the reflectance (
R
%
). The optical band gap energy (E
g
) of PMMA-MWCNTs/ZrO
2
NPs decreases from 4.063
eV
to 3.845
eV
upon injection of 5% of MWCNTs and gradually increasing the ZrO
2
concentration in PMMA matrix. Furthermore, other essential optical parameters are estimated using different classical models such as Drude, Spitzer-Fan, Sellmeier, and Wemple–DiDomenico (WDD). Interestingly, thermal stability of PMMA-MWCNTs nanocomposite films is enhanced dramatically upon increasing the content of ZrO
2
NPs. The synthesized nanocomposite thin films could be potential candidates for fabrication realistic scaled optoelectronic devices.
Nanocomposite films of polyaniline protonated with camphor sulfonic acid (PANI-CSA) hosted in polyethylene oxide (PEO) and incorporated with gallium nitride nanoparticles (GaN-NPs) were synthesized ...and characterized. Nanocomposite films were coated on activated fused silica substrates by employing the spin coating technique. Films of PANI-CSA, PEO, PANI-CSA-PEO, and PANI-CSA-PEO incorporated with GaN-NPs with a weight percent ratio of 10%, 20.07%, 38.76%, 77.83%, 93.03%, 100.78%, and 155.04% with respect to PANI-CSA were characterized using UV–Vis spectroscopy, XRD, and SEM. Refractive index (
n
), extinction coefficient (
k
), absorption coefficient (α), and bandgap energies (
E
g
) were deduced. The refractive index value of PANI-CSA-PEO at 550 nm is found to be 1.72. It increases to 1.82 when GaN-NPs have been added to PANI-CSA-PEO solution by 10 wt.%. Then, it decreased to 1.63 when GaN-NPs concentration was increased to 20.07 wt.%. When GaN-NPs is increased further to higher concentrations, the material becomes GaN-rich PANI-CSA-PEO, and the refractive index takes values ranging between 1.56 and 1.66 at the higher concentration. The typical crystalline structure of PANI-CSA was vanishing gradually as GaN-NPs content was increasing at 155% wt.%, and the GaN crystalline nature was dominating the film crystallography. Results are anticipated to contribute to preparing smart multifunctional devices based on the PANI-CSA-PEO doped with GaN-NPs.
Synthesis, optical, mechanical, and structural characterization of organic–inorganic nanocomposite thin films based on polyethylene oxide and poly(vinyl alcohol) (PVA) polymers incorporated with ...(1:0), (0.75:0.25), (0.5:0.5), (0.25:0.75), and (0:1) content percentage ratios of ZnO-NPs: Al
2
O
3
-NPs nanoparticles are reported. The optical properties, including the absorption coefficient, refractive index, extinction coefficient, dielectric function, and optical band gap for the films, are investigated from the measured transmittance and reflectance using a newly derived mathematical model. The as-grown PVA-PEO polymeric thin films exhibit transmittance of 87% while it decreases down to 75% with ZnO-NPs and decreases in between by the addition of Al
2
O
3
-NPs. However, the refractive index increases from 2.0 with ZnO-NPs to 2.7 with Al
2
O
3
-NPs. The band gap energy is from 3.98 to 3.89 eV accordingly. The dislocation density
,
crystallite size, and average internal strain obtained from the X-ray diffraction patterns exhibit abnormal behavior for equal ratio (0.5:0.5) of the two types of NPs compared with other ratios. Fourier transform infrared (FTIR) spectroscopy measurements to elucidate the major vibrational modes and bonding in the nanocomposite thin films. A redshift of the major peaks has been observed for all investigated compositional ratios indicating a shift of the absorption edge confirming the band gap reduction. The SEM micrographs show a clear form of nanocomposites with PVA-PEO/ZnO-NPs compared to those when Al
2
O
3
-NPs or a combination of the two kinds of NPs are introduced to the complex matrix. Our detailed analysis of the physical properties of PVA-PEO/ZnO-Al
2
O
3
indicates their potential to be candidate materials for modern optical and optoelectronic devices.
Abstract
This study introduces a low-field NMR spectrometer (LF-NMR) featuring a multilayer Halbach magnet supported by a combined mechanical and electrical shimming system. This setup offers ...improved field homogeneity and sensitivity compared to spectrometers relying on typical Halbach and dipole magnets. The multilayer Halbach magnet was designed and assembled using three nested cylindrical magnets, with an additional inner Halbach layer that can be rotated for mechanical shimming. The coils and shim-kernel of the electrical shimming system were constructed and coated with layers of zirconia, thermal epoxy, and silver-paste resin to facilitate passive heat dissipation and ensure mechanical and thermal stability. Furthermore, the 7-channel shim coils were divided into two parts connected in parallel, resulting in a reduction of joule heating temperatures from 96.2 to 32.6 °C. Without the shimming system, the Halbach magnet exhibits a field inhomogeneity of approximately 140 ppm over the sample volume. The probehead was designed to incorporate a solenoidal mini coil, integrated into a single planar board. This design choice aimed to enhance sensitivity, minimize
$${B}_{1}$$
B
1
inhomogeneity, and reduce impedance discrepancies, transmission loss, and signal reflections. Consequently, the resulting linewidth of water within a 3 mm length and 2.4 mm inner diameter sample volume was 4.5 Hz. To demonstrate the effectiveness of spectral editing in LF-NMR applications at 29.934 MHz, we selectively excited hydroxyl and/or methyl protons in neat acetic acid using optimal control pulses calculated through the Krotov algorithm.
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