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Negative dielectric constant and multi-visible photolumenses emissions of Cd(1-x)CoxO nanocomposites with (0.00 ≤ x ≤ 1.00)

Research Abstract

We report the photolumenses (PL) and dielectric measurements of Cd(1-x)CoxO nanocomposites with (0.00 ≤ x ≤ 1.00). It is found that an increase in x correlates with a significant change in crystallite size, particle size, porosity, Debye temperature, Young’s modulus, q-factor, binding energy, impedance of grains and their boundaries. The samples with x = 0.50 or 0.60 show an adverse change in the behavior of these parameters. We could not evaluate any shift in the wave length of PL emissions, although they are different in intensities. The samples of x = 0.40 and 1.00 show more visible emission colors at 640, 678, 716, and 791 nm. The x = 0.00 sample shows a negative dielectric constant (ε\ ), but it crossovers to positive for the other values of x. ε\ was gradually decreased as frequency increased up to 10 KHz, after which it nearly saturated except x = 0.80, in which it linearly decreased and never saturated. The ac conductivity decreased gradually against x such that the type of conduction is dependent on the chosen x. The Cole-Cole plot shows a straight line for x = 0.00 and arcs for x = 0.20 and 0.60, and a complete semicircular for x = 0.40, 0.50, 0.80 and 1.00. Furthermore, the effective capacitance was 9260 μF for x = 0.00, but it drops to 0.013 μF for x = 0.40, whereas the vice is true for bulk resistance. These results lend a reasonable certainty to the assertion that Co substitutes for Cd and make them potential prospects for devices such as diodes that emit light, cathode-luminescence displays, integrated circuits, Li-battery and supercapacitors

Research Authors
A. Sedky, Abdullah Almohammedi, N. Afify, Gh. Abbady
Research Date
Research Department
Research Journal
Inorganic Chemistry Communications
Research Year
2024

Corrosion inhibition performance of new Schiff base cyclohexanamine derivatives on C-steel in 1 M HCl solution: Electrochemical, chemical, surface and computational explorations

Research Abstract

Iron has many advantages, which makes it a material of great importance on the industrial level, but it is quickly affected by surrounding environmental factors that cause its corrosion. In this context, two new Schiff base cyclohexanamine derivatives (CSBs) were synthesized, characterized, and screened as corrosion inhibitors of Csteel in a 1 M hydrochloric acid solution. Specifically, they are (Z)-N-cyclohexyl-1-phenylethan-1-imine (CSB-1) and (E)-N′-cyclohexyl-N-hydroxybenzimidamide (CSB-2). 1 H NMR was used to determine the structures of the new CSB molecules. The inhibition efficacies (%IE) were evaluated by combining theoretical, physical, chemical, electrochemical, and spectroscopic methods. The results confirmed that CSBs were mixed-type inhibitors and that the IE depended linearly on their concentration. The adsorption of these molecules on the metal surface is key to this role. Kinetic and thermodynamic studies indicated that they are physically adsorbed and subject the Langmuir adsorption isotherm. Using 0.001 M of inhibitor, the maximum %IEs achieved were 91.1 % for CSB-1 and 94.4 % for CSB-2, respectively, which confirms tatehat they are promising inhibitors. Surface analysis via atomic force microscopy (AFM) confirmed that the C-steel was covered in a protective layer. Several thermodynamic and kinetic parameters were calculated. DFT and Mullikan charge calculations and molecular dynamics (MD) simulations were applied to predict the effectiveness and interactions of new CSBs on the steel surface as well. Theoretical expectations correspond to the practical.

Research Authors
Ahmed A. Farag, AbdulAziz A. Alayyafi, Hanan Alhussain, Ahmed Fawzy, Emad M. Masoud, Arafat Toghan
Research Date
Research Journal
Inorganic Chemistry Communications
Research Member
Research Pages
1-11
Research Publisher
Elsevier
Research Rank
1
Research Vol
163
Research Year
2025

On photo-induced electrons in graphene-plasmonic nanoparticles

Research Authors
Samar Moustafa, Jamal QM Almarashi, Mohamed Almokhtar, Hesham Fares, Mohamed K Zayed
Research Date
Research Department
Research Journal
Applied Physics A
Research Vol
129
Research Year
2023

Robust multi-mode rainbow trapping with ultra-high-Q Fano resonances

Research Abstract

We present a groundbreaking and versatile approach to multi-mode rainbow trapping in photonic crystal waveguides (PCWs), overcoming long-standing limitations in photonic device design. Our innovative semi-bilayer PC design, formed by stacking two PCs, enables the realization of new photonic modes that were previously inaccessible, leading to enhanced device flexibility, improved performance, and increased resilience to defects and imperfections. By meticulously engineering a chirped PC within the PCW, we achieve multi-mode light trapping at distinct positions for different frequencies along the waveguide, effectively creating a rainbow of light. This study paves the way for efficient and robust trapping and demultiplexing of multiple wavelengths, opening up new avenues for on-chip nanophotonic applications. Moreover, the realization of ultra-high-quality (Q) factor Fano resonances within the waveguide cavity unveils unprecedented possibilities for designing on-chip nanophotonic devices. The diverse array of Fano resonances holds immense potentials for developing novel optical filters, switches, and lasers with exceptionally low thresholds. Our proposed structure offers a more compact, efficient, and robust solution for multi-wavelength photonic device applications.

Research Authors
Sayed El Soliman, Israa Abood, Cuicui Lu
Research Date
Research Department
Research Journal
Optics Express
Research Pages
1010-1019
Research Publisher
Optica Publishing Group
Research Vol
32
Research Year
2023

Multidimensional modelling and designing of efficient small molecule acceptors for organic solar cells

Research Abstract

Chemical structural engineering is a helpful method to design the semi-conductors for organic solar cells (OSCs).
The understanding of structural and electronic properties of materials is essential for designing and calibration of
materials. By making structural adjustments at the terminal position, new small molecule acceptors can be
created. Electronic properties are studied in detail. Electrostatic potential both in qualitative and quantitative
way is studied to explore the electron density distribution. The electron density is signifcantly changed on the
change of terminal groups. The excited state behaviour has also undergone a noticeable alteration. The increase
in electron-defcient character at the terminal location causes the absorption spectra to shift to the red. The
structural changes have an important effect on non-covalent interactions also. Through molecular dynamics
(MD) simulations, the bulk behaviour of pure small molecule acceptors and their blend with polymer donor PM6
is examined. Radial distribution function is attained from MD simulations. The alteration in terminal groups has
signifcantly changed the packing behavior of pristine acceptors and their blend with polymer donor.
 

Research Authors
Beriham Basha, Muhammad Sulaman, Sayed Elshahat, Hasnain Mehdi Jafri, ZA Alrowaili, MS Al-Buriahi, Muhammad Ramzan Saeed Ashraf Janjua
Research Date
Research Department
Research Journal
Materials Science and Engineering: B
Research Pages
116618
Research Publisher
Elsevier
Research Vol
296
Research Year
2023

Topological rainbow based on coupling of topological waveguide and cavity

Research Abstract

Topological photonics and topological photonic states have opened up a new frontier
for optical manipulation and robust light trapping. The topological rainbow can separate different
frequencies of topological states into different positions. This work combines a topological
photonic crystal waveguide (topological PCW) with the optical cavity. The dipole and quadrupole
topological rainbows are realized through increasing cavity size along the coupling interface. The
flatted band can be obtained by increasing cavity length due to interaction strength between the
optical feld and defected region material which is extensively promoted. The light propagation
through the coupling interface is built on the evanescent overlapping mode tails of the localized
felds between bordering cavities. Thus, the ultra-low group velocity is realized at a cavity
length more than the lattice constant, which is appropriate for realizing an accurate and precise
topological rainbow. Hence, this is a novel release for strong localization with robust transmission
and owns the possibility to realize high-performance optical storage devices.
 

Research Authors
Sayed Elshahat, Hongyu Zhang, Cuicui Lu
Research Date
Research Department
Research Journal
Optics Express
Research Pages
20187-20199
Research Publisher
Optica Publishing Group
Research Vol
31
Research Year
2023

Topological rainbow trapping based on gradual valley photonic crystals

Research Abstract

Valley photonic crystals (PCs) play a crucial role in controlling light flow and
realizing robust nanophotonic devices. In this study, rotated gradient valley PCs
are proposed to realize topological rainbow trapping. A topological rainbow is
observed despite the presence of pillars of different shapes, which indicates the
remarkable universality of the design. Then, the loss is introduced to explore the
topological rainbow trapping of the non-Hermitian valley PC. For the step-angle
structure, the same or different losses can be applied, which does not affect the
formed topological rainbow trapping. For a single-angle structure, the applied
progressive loss can also achieve rainbow trapping. The rainbow is robust and
topologically protected in both Hermitian and non-Hermitian cases, which is
confirmed by the introduction of perturbations and defects. The proposed
method in the current study presents an intriguing step for light control and
potential applications in optical buffering and frequency routing.
 

Research Authors
Xinyue Wang, Wen Zhao, Sayed Elshahat, Cuicui Lu
Research Date
Research Department
Research Pages
1141997
Research Publisher
Frontiers Media SA
Research Vol
11
Research Year
2023

Energy Level Prediction of Organic Semiconductors for Photodetectors and Mining of a Photovoltaic Database to Search for New Building Units

Research Abstract

Due to the large versatility in organic semiconductors, selecting a suitable (organic semiconductor) material for photodetectors is a challenging task. Integrating computer science and
artificial intelligence with conventional methods in optimization and material synthesis can guide
experimental researchers to develop, design, predict and discover high-performance materials for
photodetectors. To find high-performance organic semiconductor materials for photodetectors, it is
crucial to establish a relationship between photovoltaic properties and chemical structures before
performing synthetic procedures in laboratories. Moreover, the fast prediction of energy levels is
desirable for designing better organic semiconductor photodetectors. Herein, we first collected large
sets of data containing photovoltaic properties of organic semiconductor photodetectors reported in
the literature. In addition, molecular descriptors that make it easy and fast to predict the required
properties were used to train machine learning models. Power conversion efficiency and energy
levels were also predicted. Multiple models were trained using experimental data. The light gradient
boosting machine (LGBM) regression model and Hist gradient booting regression model are the
best models. The best models were further tuned to achieve better prediction ability. The reliability
of our designed approach was further verified by mining the photovoltaic database to search for
new building units. The results revealed that good consistency is obtained between experimental
outcomes and model predictions, indicating that machine learning is a powerful approach to predict
the properties of photodetectors, which can facilitate their rapid development in various fields.
 

Research Authors
Jehad Saleh, Sajjad Haider, Muhammad Saeed Akhtar, Muhammad Saqib, Muqadas Javed, Sayed Elshahat, Ghulam Mustafa Kamal
Research Date
Research Department
Research Journal
Molecules
Research Pages
1240
Research Publisher
MDPI
Research Vol
28
Research Year
2023

Raman characteristics of graphene/quartz and graphene/Ag nanoparticles/quartz substrate: Laser power dependence

Research Abstract

The sensitivity of graphene surface to adjacent conditions plays an important role that modifies the performance and characteristics of graphene devices working under ambient conditions. Quartz is a dielectric transparent material with excellent optical transmission and therefore graphene/quartz is widely used in graphene device technology. Here, graphene/quartz and graphene/plasmonic nanoparticle/quartz structures were investigated using Raman spectroscopy for applications in nanotechnology like graphene quartz fiber (GQF) multifunctional electrode. Optically induced shift of the Fermi level of graphene monolayer on quartz substrates and on Ag nanoparticles (NPs) distributed on quartz substrates was tracked by increasing the applied laser power. Strained graphene attached to quartz substrate, thermal effects, and charge transfer were discussed using the evolution of the G-peak characteristics. Well …

Research Authors
Naglaa Abdel All, Ghada Khouqeer, Mohamed Almokhtar
Research Date
Research Department
Research Journal
Optical Materials
Research Year
2024

Tunning carrier concentration and Fermi-level in substrate-supported graphene monolayers: Effect of laser power

Research Abstract

Tunning the carrier concentration n and the position of Fermi-level E F in graphene monolayers has a great impact on the design and fabrication of next generation graphene-based devices. Raman spectral properties of graphene/SiO 2/Si and graphene/Al 2 O 3 are investigated over a wide range of laser power (P L= 1 to 25 m W). The increase in P L results in significant variations in position and half-width of the G-band, allowing the determination of n and E F using nonadiabatic fitting. The initially formed p-type graphene is converted to n-type with increasing P L due to charge transfer to/from graphene with the substrate interfacial defect states and/or redox interactions with environmental gas. Whereas n and E F of the graphene/SiO 2/Si reach saturation at P L= 12 m W, those of graphene/Al 2 O 3 exhibit a monotonic increase before saturating at P L> 21 m W. A noticeable enhancement in graphene quality …

Research Authors
Mohamed K Zayed, Hesham Fares, Mohamed Almokhtar
Research Date
Research Department
Research Journal
Applied Surface Science
Research Pages
158487
Research Publisher
North-Holland
Research Vol
641
Research Year
2023
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