Mahmmoud Sayed Abd El-sadek | South Valley University (original) (raw)

Books by Mahmmoud Sayed Abd El-sadek

A simple synthetic route for the development of CdTe nanocrystals in aqueous system with Mercapto... more A simple synthetic route for the development of CdTe nanocrystals in aqueous system with Mercaptoacetic Acid (MAA) as a stabilizer at room temperature was presented in chapter 2. Also, the effect of nanocrystal size on the crystalline structure, the absorption bands and photoluminescence emission were discussed. The effect of pH value of the precursor solution on the optical properties of CdTe nanocrystals was correlated. Additionally, Microwave irradiation method was used for the synthesis of water-soluble CdTe nanocrystals in aqueous phase. The effect of microwave irradiation and experimental conditions on the synthesis of CdTe nanocrystals was investigated. The synthesized samples were characterized and the results are discussed.

Papers by Mahmmoud Sayed Abd El-sadek

Advances in Nanoparticles, 2013

The effect of modification of TiO 2 with different palladium concentrations on its characteristic... more The effect of modification of TiO 2 with different palladium concentrations on its characteristics and photocatalytic efficiency was studied. Photo catalysts were prepared by the sol-gel method and were characterized by different techniques. A uniform distribution of palladium through the TiO 2 matrix was observed. The X-ray diffraction patterns of the pure and palladium doped TiO 2 were found to be quiet similar and the average particle size was not significantly changed. As a result of palladium doping, the UV-Vis analysis showed a red shift in the onset of wavelength of absorbance and the band gap was changed from 3.39 to 3.06 eV for the 0.3 wt% Pd/TiO 2 sample. Photo catalytic removal study of formic acid showed that the 0.3 wt% palladium doped photocatalyst exhibits the highest efficiency among the different palladium doped photocatalysts using sun light as the radiation source.

American journal of mechanical engineering, 2019

Composite material nowadays has a competitive role in controlling other material. Therefore, coat... more Composite material nowadays has a competitive role in controlling other material. Therefore, coating other material using such composite material help to enhance the mechanical compressive and failure strength of deteriorates ancient materials Thebes limestone is attractive source for a lot of researcher. Natural weathering like rains, rockslides, moisture, salty groundwater absorption and changing temperature can damage or even may weaken the strength of such deteriorates ancient buildings. Compression Samples of ancient Thebes limestone are coated with Nano calcium carbonate and Nano Calcium Hydroxide. While single edge notch bending samples are treated cracked face using Nano calcium carbonate. The results showed an enhancement in both compression and fracture strength.

Applied Physics A, 2019

Cadmium sulfide (CdS) nanoparticles were prepared by hydrothermal method at 150 °C under differen... more Cadmium sulfide (CdS) nanoparticles were prepared by hydrothermal method at 150 °C under different reaction times. It was found that hydrothermal method is an effective, quick, and eco-friendly method to synthesis CdS nanoparticles of hexagonal structure at lower temperature. X-ray peak profile analysis by Williamson-Hall analysis and size-strain plot was employed to estimate the crystallite size and lattice strain of the synthesized CdS nanoparticles and to investigate their effects on the peak broadening. The values of strain, stress and energy density were determined for all XRD peaks of wurtzite hexagonal phase of CdS, by applying various forms of Williamson-Hall procedure, such as UDM (uniform deformation model), USDM (uniform stress deformation model) and UDEDM (uniform deformation energy density model). The obtained results indicate that the crystallite size of CdS nanoparticles estimated from Scherrer equation, Williamson-Hall plots and size-strain plot, are nearly similar and in the range of 14-37 nm. CdS nanoparticles were also investigated using high-resolution transmission electron microscopy (HR-TEM), Fourier transform infra-red spectroscopy (FT-IR), and UV-visible and fluorescence spectroscopy. A dependence of the band gap and the nanoparticle size on the reaction time was reported.

Journal of Magnetism and Magnetic Materials, 2016

Ferrimagnetic oxides may contain single or multi domain particles which get converted into superp... more Ferrimagnetic oxides may contain single or multi domain particles which get converted into superparamagnetic state near a critical size. To explore the existence of these particles, we have made Mössbauer and magnetic studies of Cu 2+ substitution effect in CoFe 2-x O 4 Ferrites (0.0, 0.1, 0.2, 0.3, 0.4, and 0.5). All the samples have a cubic spinel structure with lattice parameters, increasing linearly with increase in Cu content. The hysteresis loops yield a saturation magnetization, coercive field, and remanent magnetization that vary significantly 2 with Cu content. The magnetic hysteresis curves show a reduction in saturation magnetization and an increase in coercitivity with Cu 2+ ion substitution. The anisotropy constant, K 1, is found strongly dependent on the composition of Cu 2+ ions. The variation of saturation magnetization in increasing Cu 2+ ion content has been explained in the light of Neel's molecular field theory. Mössbauer spectra at room temperature show two ferrimagnetically relaxed Zeeman sextets. The dependence of Mössbauer parameters such as isomer shift, quadrupole splitting, line width and hyperfine magnetic field on Cu 2+ ion concentration have been discussed.

Water-Soluble and fluorescent thiol capped CdSe quantum dots (QDs) were synthesized by chemical r... more Water-Soluble and fluorescent thiol capped CdSe quantum dots (QDs) were synthesized by chemical rout. The structure of CdSe QDs was investigated by means of X–ray diffraction (XRD), energy–dispersive X–ray analysis (EDX), UV–visible, Fourier transform infrared (FT–IR) spectroscopy and transmission electron microscopy (TEM). The crystal phase of the CdSe QDs confirmed with XRD diffraction technique. The average size of CdSe QDs was calculated to be 3 nm by different spectroscopic techniques. CdSe capped with mercaptopropionic acid (MPA) shows a characteristic fluorescent peak at 590 nm, which is highly dependant on the pH value. The interaction of the water-soluble MPA–CdSe and acivicin (AC) was investigated in 50 mM sodium acetate buffer pH 7.4 by fluorescence spectroscopy. The interaction between acivicin and MPA–CdSe shows a dynamic quenching process. Analysis of the circular dichorism (CD) spectra indicated higher interaction of the MPA–CdSe-AC complex with human serum albumin th...

In this work we have performed a modified organometallic method for synthesis of CdSe core and Cd... more In this work we have performed a modified organometallic method for synthesis of CdSe core and CdSe/ZnS core/shell quantum dots of different sizes at room temperature. In this organometallic scheme, one-pot synthesis of core/shell nanocrystalls in HDA-TOPO-TOP mixture is used. The structural features were determined with x-ray powder diffraction and all direction peaks are consistent with the wurtzite structure. The results of x-ray diffraction and high-resolution transmission electron microscopy (HR-TEM) revealed that the prepared CdSe/ZnS quantum dots QDs had a core/shell structure with high crystallinity. The estimated average of the particle size was found to be ~3.10 nm for core and 4.25 nm for core/shell by a TEM image. The average sizes of QDs were also estimated by using various ways such as the Sherrer's formula and the Yu et al theoretical expression. The obtained CdSe and CdSe/ZnS nanocrystals were characterized by using UV-vis spectroscopy which confirmed that a seri...

The electrochemical etching method has been used to fabricate and characterize a metallic tip bas... more The electrochemical etching method has been used to fabricate and characterize a metallic tip base on quarts tuning fork for use in combined scanning tunneling and atomic force microscope STM/AFM. The main advantage of this method is that it allows manufacturing a high quality factor tuning fork force detector with a clean and single super sharp, which is made of platinum (or platinum alloys). The fabricated tips has radius of curvature of several nanometer (<10 nm). Moreover, these super sharp tips are quite strong against occasionally occurring tip crashes which is acceptable for a good resolution in the scanning probe microscope.

The European Physical Journal Plus

The influence of annealing temperature in the range 400–550 nm on the SnS thin films, synthesized... more The influence of annealing temperature in the range 400–550 nm on the SnS thin films, synthesized via thermal evaporation method, is investigated. The structure of tin sulfide annealed films is examined through X-ray diffraction (XRD), revealing crystalline nature with the orthorhombic structure of the main peak (111) at 2θ = 31.38Ǻ. Micro-strain and dislocation density are decreased as the annealing temperature increased. The optical energy gap of these films is computed using the data of transmittance, reflectance, and absorption spectra over a wavelength range of 300–1200 nm. The energy gap decreases with increasing annealing temperature: Egdir = 1.77 to 1.62 eV and Egind = 1.21 to 1.08 eV. The volume and surface energy loss function increased as the annealing increased. In addition, the real and imaginary inter-band transition strength was calculated using dielectric constants. Optical conductivity (σopt) and penetration depth of light (δdp) depend on wavelength calculated using absorption coefficient: (σopt) = 2.4 × 1011 to 0.9 × 1011 Ω−1.m−1 at 2.25 eV and δdp = 0.04 to 0.006 at 1050 nm, respectively. The skin depth of these films provides a cut-off wavelength at ≈ 600 nm. Besides, the skin depth of these films decreases as annealing temperature increased.

Applied Nanoscience

Nanocrystalline lead zirconate titanate (PZT) powders were synthesized via a modified Pechini met... more Nanocrystalline lead zirconate titanate (PZT) powders were synthesized via a modified Pechini method. The effect of heat treatment temperature on the microstructural properties was studied using X-ray powder diffraction. The explored temperatures were identified from the TGA/DSC measurement and it is found that the crystallization starts from 550 °C. Rietveld refinement was applied to study structural changes and to quantitatively assess the fractional content of lead monoxide, identified in nano-PZT powders. Lebail method was carried out to the XRD pattern to accurately determine the peak broadening and position. Size-Strain Plot and various Williamson-Hall methods were used to calculate the lattice microstrain and crystallite size. The minimum strain was noticed in the pure tetragonal-PZT sample. TEM technique was also employed to study nanopowders and to confirm the formation of small-sized particles. The energy band gap was determined by diffused reflectance measurements and found to range from 3.17 to 3.29 eV.

Applied Physics A

The multiphase TixZr1−xO2 (0 ≤ x ≤ 1) nanoparticles were prepared by co-precipitation method. The... more The multiphase TixZr1−xO2 (0 ≤ x ≤ 1) nanoparticles were prepared by co-precipitation method. The samples were stable at temperatures > 300 °C, so the samples were calcined at 600 °C to be more stable. The ZrO2 crystallite size nanoparticles is 13.19 nm with monoclinic mixed tetragonal structure, 36.97 nm for TiO2 nanoparticles with anatase and rutile mixed phase and 6–10 nm for TixZr1−xO2; (x = 0.2, 0.4, 0.5, 0.6 and 0.8) with orthorhombic phase except the sample Ti0.8Zr0.2O2 nanoparticles that had anatase phase of TiO2 mixed with tetragonal phase of ZrO2. TEM results show the morphology of the samples with spherical shape and the particle size was in the range 8–26 nm. The presence of titanium decreases the optical band gap of ZrO2 and converts it from ceramic materials to semiconductor materials. The addition of Ti enhanced the mechanical properties of TixZr1-xO2 (0 ≤ x ≤ 1) composites. The hardness increased from 0.51 GPa (ZrO2) to 0.55 GPa (Ti0.5Zr0.5O2).

The European Physical Journal Plus

Abstract. CdS@Mn(OH)2 nanocomposites were prepared using a novel aqueous seed-mediated growth app... more Abstract. CdS@Mn(OH)2 nanocomposites were prepared using a novel aqueous seed-mediated growth approach. The CdS@Mn(OH)2 nanocomposites were characterized by means of X-Ray Diffraction, Energy-Dispersive X-ray analysis, Transmission Electron Microscopy and FT-IR analysis. The MAA-CdS and CdS@Mn(OH)2 composite nanoparticles average size was about 3.2 nm and 5.1 nm, respectively. The refluxing time and the concentration effect of Mn2+ on the nanocomposite optical properties were studied using UV-visible absorption and photoluminescence techniques. The CdS@Mn(OH)2 composite nanoparticles emission peak was shifted from 508 nm to 536 nm, which indicates the successful doping of Mn2+ into CdS nanoparticles. An efficient energy transfer process was observed from the bare MAA-CdS nanoparticles to the CdS@Mn(OH)2 nanocomposite.

Applied Physics A

Influence of synthesis temperature and reaction time on the structural and optical properties of ... more Influence of synthesis temperature and reaction time on the structural and optical properties of ZnO nanoparticles synthesized by the hydrothermal method was investigated using X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray, Fourier transform infra-red spectroscopy, and UV–visible and fluorescence spectroscopy. The XRD pattern and HR-TEM images confirmed the presence of crystalline hexagonal wurtzite ZnO nanoparticles with average crystallite size in the range 30–40 nm. Their energy gap determined by fluorescence was found to depend on the synthesis temperature and reaction time with values in the range 2.90–3.78 eV. Thermal analysis, thermogravimetric and the differential scanning calorimetry were used to study the thermal reactions and weight loss with heat of the prepared ZnO nanoparticles.

Materials Science-Poland

This paper attempts to describe an effective method for producing a composite of quantum dots con... more This paper attempts to describe an effective method for producing a composite of quantum dots consisting of CdSe (core) with CdS (shell). This nanoparticles composite was synthesized from modified organometallic precursors. The sizes of the nanoparticles were estimated from X-ray diffraction data using Debye-Scherer formula and compared with high resolution electron microscopy (HRTEM) and optical spectra. The shape of CdSe/CdS NPs is nearly spherical and revels that the CdS shell with the thickness ~0.6 nm almost fully covers the CdSe core (higher contrast). Using UV-Vis spectroscopy, a systematic red shift in the absorption and emission spectra was observed after the deposition of CdS which confirms the shell growth over the CdSe core. In the CdSe/CdS core/shell structure, the holes are confined to the core, while the electrons are delocalized as a result of similar electron affinities of the core and the shell. The increased time of synthesis resulted in shell thickness increase. ...

Materials Chemistry and Physics

Abstract In this study, we report the preparation of different Sb 2 S 3 morphologies in the same ... more Abstract In this study, we report the preparation of different Sb 2 S 3 morphologies in the same experimental setup. We utilized the method of vapor phase transport with direct evaporation of high purity Sb 2 S 3 powder on quartz and Si (100) substrates. The deposited Sb 2 S 3 nanostructures showed different morphologies and crystallinities without using metal catalyst seed layers. The successfully formed Sb 2 S 3 morphologies were nanowires, nanorods, nanodendrites and nanoparticles, as verified by the scanning electron microscopy and transmission electron microscopy analysis. We found that the physical characteristics of the final product are a function of the differential temperature inside the furnace tube. The X-ray diffraction analysis confirmed the formation of the orthorhombic pure phase of crystalline stibnite-Sb 2 S 3 . The energy-dispersive X-ray spectroscopy spectra validated the high purity of the synthesized products. Moreover, the relation of the morphology and the optical and electrical properties of Sb 2 S 3 thin films have been studied by various techniques. The optical analysis by UV–vis–near-infrared (NIR) spectroscopy shows that the optical band gaps of the different synthesized films range from 1.64 to 1.92 eV. The refractive indices ( n ) of Sb 2 S 3 thin films were found to be morphology dependent. The film with nanoparticles morphology has the highest n value of 2.1 and the film with nanowires morphology has the lowest n value of 1.97. In all prepared samples photoluminescence (PL) spectra exhibit a distinct emission peak at 615 nm (⁓ 2.02 eV) in terms of intensity and FWHM. The dc-electrical conductivity of various Sb 2 S 3 nanostructures is thermally activated according to Arrhenius law with two types of conduction mechanisms. The conduction in the high temperature and lower temperature zones is due to the hopping conduction via localized states and the thermionic emission respectively. The study provides a framework for future research in semiconductor nanomaterials with controllable morphologies for applications of optoelectronics.

Applied Physics A, 2019

Cadmium sulfide (CdS) nanoparticles were prepared by hydrothermal method at 150 °C under differen... more Cadmium sulfide (CdS) nanoparticles were prepared by hydrothermal method at 150 °C under different reaction times. It was found that hydrothermal method is an effective, quick, and eco-friendly method to synthesis CdS nanoparticles of hexagonal structure at lower temperature. X-ray peak profile analysis by Williamson–Hall analysis and size–strain plot was employed to estimate the crystallite size and lattice strain of the synthesized CdS nanoparticles and to investigate their effects on the peak broadening. The values of strain, stress and energy density were determined for all XRD peaks of wurtzite hexagonal phase of CdS, by applying various forms of Williamson–Hall procedure, such as UDM (uniform deformation model), USDM (uniform stress deformation model) and UDEDM (uniform deformation energy density model). The obtained results indicate that the crystallite size of CdS nanoparticles estimated from Scherrer equation, Williamson–Hall plots and size–strain plot, are nearly similar a...

Journal of Materials Science: Materials in Electronics

Molecular beam epitaxy was applied to evaporate a set of Au/ZnTe:I/CdTe:I/GaAs/In heterostructure... more Molecular beam epitaxy was applied to evaporate a set of Au/ZnTe:I/CdTe:I/GaAs/In heterostructures. The resulted heterostructures were examined for photovoltaic energy conversion application. Electrical characteristics were studied for understanding the relevant electrical transport mechanisms. The current–voltage (I–V) characteristics were checked under dark and light conditions. Ideality factor indicates the recombination mechanisms in the designed device; its value equals (3.22). Under various light intensities (1–140 mW cm−2), the I–V curves are affected highly by reverse voltage bias. The open-circuit voltage increases exponentially with the illumination and its values of this device increased with increasing light intensity (L), where 55 mV at 1 mW cm−2 and 465 mV at 140 mW cm−2. Electrical as well as power related parameters of the designed device were interpreted. Photosensitivity and Responsitivity of the studied device showed a high photoresponse under different light intensities. Au/ZnTe:I/CdTe:I/GaAs/In heterostructures is a promising material for photosensor and optoelectronic applications.

Advances in Nanoparticles, 2013

American journal of mechanical engineering, 2019

Applied Physics A, 2019

Journal of Magnetism and Magnetic Materials, 2016

The European Physical Journal Plus

Applied Nanoscience

Applied Physics A

The European Physical Journal Plus

Applied Physics A

Materials Science-Poland

Materials Chemistry and Physics

Applied Physics A, 2019

Cadmium sulfide (CdS) nanoparticles were prepared by hydrothermal method at 150 °C under differen... more Cadmium sulfide (CdS) nanoparticles were prepared by hydrothermal method at 150 °C under different reaction times. It was found that hydrothermal method is an effective, quick, and eco-friendly method to synthesis CdS nanoparticles of hexagonal structure at lower temperature. X-ray peak profile analysis by Williamson–Hall analysis and size–strain plot was employed to estimate the crystallite size and lattice strain of the synthesized CdS nanoparticles and to investigate their effects on the peak broadening. The values of strain, stress and energy density were determined for all XRD peaks of wurtzite hexagonal phase of CdS, by applying various forms of Williamson–Hall procedure, such as UDM (uniform deformation model), USDM (uniform stress deformation model) and UDEDM (uniform deformation energy density model). The obtained results indicate that the crystallite size of CdS nanoparticles estimated from Scherrer equation, Williamson–Hall plots and size–strain plot, are nearly similar a...

Journal of Materials Science: Materials in Electronics

Materials Research Express

The influence of precursor and solvent type on the structural and optical properties of ZnO nanop... more The influence of precursor and solvent type on the structural and optical properties of ZnO nanoparticles synthesized through co-precipitation technique was investigated. The phase formation of the samples was studied by x-ray diffraction which confirmed single phase hexagonal wurtzite nature of the samples. X-ray profiles showed that the particle size of the synthesized samples decreases with changing the precursor and solvent. The high-resolution transmission electron microscopy (HR-TEM) confirms nanoparticles with an average crystallite size 13–32 nm with different precursors and solvents. The energy-dispersive x-ray analysis showed purity of samples as no unwanted element was traced in the prepared nanomaterials. The energy gap determined by fluorescence depends on the type of the solvent and precursor, and its values were reordered in the range 3.33–3.62 eV. For studying the thermal stability of the synthesized ZnO nanoparticles, a thermal analysis was carried out using thermogravimetric and the differential scanning calorimetry. For antibacterial activity, the synthesized ZnO nanoparticles are strongly antimicrobial as they successfully inhibited the growth of the tested micro-organisms.