Journal of Materials Science: Materials in Electronics, 2015
Magnesium-substituted lithium ferrite powders (Li1−xMg2xFe5−xO8 where x = 0.0–0.8) were prepared ... more Magnesium-substituted lithium ferrite powders (Li1−xMg2xFe5−xO8 where x = 0.0–0.8) were prepared by sol–gel auto-combustion method. XRD profiles revealed that all compositions were single cubic ferrite structure for the precursors annealed at 800 °C for 2 h. The crystallite size was found to decrease whereas the lattice parameter was increased with increasing Mg2+ ion content. The microstructure of the formed powders was Mg concentration dependent. Increasing the Mg2+ ion ratio was found to inhibit the grain growth of the formed ferrite. The AC electrical conductivity of Mg2+ ion substituted lithium ferrite samples was raised with increasing the concentration of Mg2+ ions as the result of increasing the hopping of electrons between Fe2+ and Fe3+ ions. Meanwhile, dielectric constant (ε′) was diminished with increasing the frequency of external electric field as well as increasing the temperature and concentration of Mg2+ ions. Alongside, the formed crystalline magnesium substituted lithium ferrite had good magnetic properties. High saturation magnetization (78.7 emu/g) was attained by the formed ferrite sample at Mg2+ molar ratio of 0.4 annealed at 800 °C for 2 h.
Four glasses of (V 2 O 5 ) 0.3 –(P 2 O 5 ) 0.6 –(MO) 0.1 where MO=(TeO 2 , GeO 2 , Bi 2 O 3 or P ... more Four glasses of (V 2 O 5 ) 0.3 –(P 2 O 5 ) 0.6 –(MO) 0.1 where MO=(TeO 2 , GeO 2 , Bi 2 O 3 or P 2 O 5 ) were prepared by melting the appropriate amounts of V 2 O 5 , MO and (NH 4 ) 2 HPO 4 in an open crucible. The structures of the virgin and annealed glasses (at 673 K for 24 h) were studied using density, FT-IR, X-ray diffraction (XRD), electron spin resonance (ESR) and scanning electron microscope (SEM). The electrical conductivity (σ), dielectric constant ( e ′ ) and dielectric loss ( e ′′ ) for the virgin and annealed glasses are investigated over a temperature range between 78 and 450 K and at a frequency from dc to 10 6 Hz. At low temperatures the conductivity data are explained on the basis of variable range hopping mechanism, while at high temperatures the Mott's models of phonon assisted polaronic conductivity is consistent with the conductivity data. The ac-conductivity increased with frequency according to σ ac (ω)=Aω s , where s has a value depending on the temperature and the composition of ...
Journal of Thermal Analysis and Calorimetry - J THERM ANAL CALORIM, 1998
The crystallization kinetics of the γ-irradiated and the unirradiated glass Ag7I4VO4 was studied ... more The crystallization kinetics of the γ-irradiated and the unirradiated glass Ag7I4VO4 was studied dynamically by means of DTA, and isothermally via electrical conductivity measurements. The influence of doping with alkali metal ions (Li+, Na+, K+, Rb+ or Cs+) on the crystallization process in the glass was also investigated. The results showed that the rate of crystallization depends on the nature of the added metal ion and on the crystallization growth mechanism. The latter is a two-dimensional process for both the pure and the alkali metal-doped glasses. The effects of irradiation and additive ions on the crystallization process are discussed.
The effect of heat treatment and substitution of vanadium by other transition metal ions, such as... more The effect of heat treatment and substitution of vanadium by other transition metal ions, such as Cr3+ or Mn4+ in (V2O5)0.8–(P2O5)0.2 glass on the electrical conductivity, dielectric constant, dielectric loss, and magnetic susceptibility has been studied over a temperature range of 80–400 K and frequencies of 102–106 Hz. The ac conductivity, σac, was found to be increased by annealing and decreased by the replacement of vanadium with Mn4+ or Cr3+ ions. The σac value increased with the measuring frequency ω according to σac(ω)=A(ω)s, where s has a value in the range of 0.33–0.48. Dielectric loss e showed maxima at temperatures depending on the sample composition and the measuring frequency. The magnetic susceptibility χ was found to increase by annealing and by introducing Cr3+ or Mn4+ into glass materials. The results obtained were explained on the basis of a mutual interaction, which is exclusively occurring between double redox pairs during the sample preparation or during the annealing process, to prod...
The effect of increasing the annealing temperature on the CdS incorporated in silica xerogel thin... more The effect of increasing the annealing temperature on the CdS incorporated in silica xerogel thin film glasses is evaluated. The thin film samples are prepared via silica gels containing solution mixture of (CdCl2 and thiourea) with molar ratio 1:1, 5 mol % from this mixture solution was added to the host silica gel precursor. X-ray diffraction and Scanning electron microscope make it possible to evaluate the sample structure and the morphology. The absorption edge exhibited a blue shift by decreasing the annealing temperature, and its energy shift was reciprocally proportional to the radius. The energy band gap shifted upward in energy for smaller nano-particle size.
The glass–ceramic with the composition x(LiFe5O8)/(100 – x) SiO2 (x 20, 30, 40, 50, 100 wt. % )... more The glass–ceramic with the composition x(LiFe5O8)/(100 – x) SiO2 (x 20, 30, 40, 50, 100 wt. % ) were prepared by sol gel auto-combustion method. The influence of the SiO2 ratio in the glass-ceramics strucure prepared was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Crystalline phases (LiFe5O8, SiO2, Fe2O3) were observed by X-ray powder diffraction in the glasses annealed at 800 C for 2h. The crystallite size was found to increase from 27.29 nm (x 20%) to 91.48 nm (x 100 %). The microstructure of the formed powders was SiO2 ratio dependent. Increasing the SiO2 ratio was found to inhibit the grain growth of the formed ferrite. The electrical conductivity of glass-ceramics samples were raised with increasing the concentration of SiO2 ratio as the result of increasing the hopping of electrons between Fe2+ and Fe3+ ions. The magnetic characteristics of the prepared glass ceramics were performed using a vibrating sample magnetometer in function of...
2016 18th International Conference on Transparent Optical Networks (ICTON), 2016
The effect of increasing temperature on the optical, spectroscopic and structural properties of p... more The effect of increasing temperature on the optical, spectroscopic and structural properties of phospho-silicate nano-composites thin films SPNCTF and monolith SPNCM were studied. Doping the mentioned prepared forms of sample with some rare earth oxide such as Neodymium (Nd3+), Erbium (Er3+), Holmium (Ho3+) etc… SPNCRETF and SPNCREM have been prepared. Such materials could be promising for wave guide application, up-down shifting harvesting solar cell and could allow fabricating small devices with high gain in the telecommunication wavelength bands. The X-Ray diffraction XRD phases of the prepared samples deposited on appropriate substrates are analysed. The structural study revealed that the crystallite sizes of monolith and thin film phospho-silicate is in the nano-scale. The photo-luminescence properties have analyzed in the visible wavelength range as a function of sample composition. The optical properties will be studied by measuring the normal transmission and specular reflection, moreover the refractive index of the prepared samples will be calculated.
Abstract: The effect of composition in the ionic glassy system AgI-Ag2O3- Bi2O3-B2O3 on the elect... more Abstract: The effect of composition in the ionic glassy system AgI-Ag2O3- Bi2O3-B2O3 on the electrical properties was investigated. The glasses have been prepared by melt quenching technique. The synthesized materials with up to 40 mol% AgI were formed in amorphous form. Above this value, the materials were only partially amorphous and contained crystalline inclusions, which were identified as AgI. The electrical conductivity (, dielectric constant (ε') and dielectric loss ('') studies of the samples have been carried out at different temperatures and frequencies. The conductivity of the glasses increased with the increase in the AgI content and attains a highest ionic conductivity value with a composition of (AgI)0.3(Ag2O)0.2(Bi2O3)0.25(B2O3)0.25. The electrical data are discussed on the basis of Ag+ diffusion in the glassy structure, which plays a significant role in both conduction and dielectric relaxation processes in the glass matrix. Key words: Ionic conduc...
In a dietary survey, large numbers of a wide variety of food samples have to be analyzed. The ato... more In a dietary survey, large numbers of a wide variety of food samples have to be analyzed. The atomic absorption spectroscopy (AAS), with its simplicity, accuracy and rapidity, suggests itself for determination of many elements in such a case. In this investigation, calcium determination by AAS is reviewed. Analytical parameters, interferences and their control are studied. Food samples are dry ashed and treated so as to eliminate silicates. Most serious interference comes from phosphates and is successfully controlled by addition of lanthanum. Calcium is determined in the range 2-10 ppm with a sensitivity of 0.1 ppm. Single food samples and samples representing food mixtures are analyzed, and calcium intake of different population groups is computed. In most cases, results compare favourably well with those obtained from food composition tables. Calcium intake in the Netherlands both of the average per caput and of chosen population groups is found to cover the recommendations excep...
To evaluate beta-endorphin secretion in euprolactinemic cases of luteal phase defect (LPD). Seria... more To evaluate beta-endorphin secretion in euprolactinemic cases of luteal phase defect (LPD). Serial blood samples from the 18th to the 26th day of the menstrual cycle were assayed for beta-endorphin, progesterone (P), estradiol (E2), and prolactin (PRL) in cases of LPD and controls. Diagnosis of LPD was based on determinations of serum P and premenstrual endometrial biopsy. From Cairo University Hospitals. PATIENT, PARTICIPANTS: Twenty-six women with LPD and 8 normal fertile women (controls) were chosen. None. beta-Endorphin, P, E2, and PRL concentrations were determined by the corresponding 125I radioimmunoassay. Plasma beta-endorphin level in cases of LPD varied from 2.58 to 9.14 pmol/L, whereas the level of controls varied from 2.41 to 5.57 pmol/L. The mean value of plasma beta-endorphin in cases of LPD was significantly higher than that of controls by 146% (P less than 0.0005). In spite of the significant decrease of serum P in cases of LPD, serum E2 level did not differ signific...
ABSTRACT a b s t r a c t In the present study, nano-sized ZnO particle-reinforced Sn–3.0Ag–0.5Cu ... more ABSTRACT a b s t r a c t In the present study, nano-sized ZnO particle-reinforced Sn–3.0Ag–0.5Cu (SAC305) composite solder was prepared by mechanically dispersing nano-particles into SAC305 solder at 900 1C for 2 h. The effects of ZnO addition on microstructure, melting behavior and corresponding mechanical properties of SAC305 solder were explored. Microstructure analysis revealed that the wurtzite ZnO particles were effective in reducing both the β-Sn grain size and spacing between Ag 3 Sn and Cu 6 Sn 5 particles. The refined microstructure, which resulted in a strong adsorption effect and high surface-free energy of ZnO nanoparticles, could obstruct the dislocation slipping, and thus provides classical dispersion strengthen-ing mechanism. This apparently enhances the yield stress (0.2%YS) and ultimate tensile strength (UTS) of SAC(305)–0.7%ZnO composite solder, whereas its ductility is lower than that of the SAC305 solder. In addition, ZnO particles keep the melting temperature of composite solder nearly at the SAC305 level although the pasty range is decreased. Empirical equations for 0.2% YS, UTS and elastic modulus E with the strain rate have been developed and the predicted tensile parameters for both solders are reasonably close to the present experimental data. & 2014 Elsevier B.V. All rights reserved.
Journal of Materials Science: Materials in Electronics, 2015
Magnesium-substituted lithium ferrite powders (Li1−xMg2xFe5−xO8 where x = 0.0–0.8) were prepared ... more Magnesium-substituted lithium ferrite powders (Li1−xMg2xFe5−xO8 where x = 0.0–0.8) were prepared by sol–gel auto-combustion method. XRD profiles revealed that all compositions were single cubic ferrite structure for the precursors annealed at 800 °C for 2 h. The crystallite size was found to decrease whereas the lattice parameter was increased with increasing Mg2+ ion content. The microstructure of the formed powders was Mg concentration dependent. Increasing the Mg2+ ion ratio was found to inhibit the grain growth of the formed ferrite. The AC electrical conductivity of Mg2+ ion substituted lithium ferrite samples was raised with increasing the concentration of Mg2+ ions as the result of increasing the hopping of electrons between Fe2+ and Fe3+ ions. Meanwhile, dielectric constant (ε′) was diminished with increasing the frequency of external electric field as well as increasing the temperature and concentration of Mg2+ ions. Alongside, the formed crystalline magnesium substituted lithium ferrite had good magnetic properties. High saturation magnetization (78.7 emu/g) was attained by the formed ferrite sample at Mg2+ molar ratio of 0.4 annealed at 800 °C for 2 h.
Four glasses of (V 2 O 5 ) 0.3 –(P 2 O 5 ) 0.6 –(MO) 0.1 where MO=(TeO 2 , GeO 2 , Bi 2 O 3 or P ... more Four glasses of (V 2 O 5 ) 0.3 –(P 2 O 5 ) 0.6 –(MO) 0.1 where MO=(TeO 2 , GeO 2 , Bi 2 O 3 or P 2 O 5 ) were prepared by melting the appropriate amounts of V 2 O 5 , MO and (NH 4 ) 2 HPO 4 in an open crucible. The structures of the virgin and annealed glasses (at 673 K for 24 h) were studied using density, FT-IR, X-ray diffraction (XRD), electron spin resonance (ESR) and scanning electron microscope (SEM). The electrical conductivity (σ), dielectric constant ( e ′ ) and dielectric loss ( e ′′ ) for the virgin and annealed glasses are investigated over a temperature range between 78 and 450 K and at a frequency from dc to 10 6 Hz. At low temperatures the conductivity data are explained on the basis of variable range hopping mechanism, while at high temperatures the Mott's models of phonon assisted polaronic conductivity is consistent with the conductivity data. The ac-conductivity increased with frequency according to σ ac (ω)=Aω s , where s has a value depending on the temperature and the composition of ...
Journal of Thermal Analysis and Calorimetry - J THERM ANAL CALORIM, 1998
The crystallization kinetics of the γ-irradiated and the unirradiated glass Ag7I4VO4 was studied ... more The crystallization kinetics of the γ-irradiated and the unirradiated glass Ag7I4VO4 was studied dynamically by means of DTA, and isothermally via electrical conductivity measurements. The influence of doping with alkali metal ions (Li+, Na+, K+, Rb+ or Cs+) on the crystallization process in the glass was also investigated. The results showed that the rate of crystallization depends on the nature of the added metal ion and on the crystallization growth mechanism. The latter is a two-dimensional process for both the pure and the alkali metal-doped glasses. The effects of irradiation and additive ions on the crystallization process are discussed.
The effect of heat treatment and substitution of vanadium by other transition metal ions, such as... more The effect of heat treatment and substitution of vanadium by other transition metal ions, such as Cr3+ or Mn4+ in (V2O5)0.8–(P2O5)0.2 glass on the electrical conductivity, dielectric constant, dielectric loss, and magnetic susceptibility has been studied over a temperature range of 80–400 K and frequencies of 102–106 Hz. The ac conductivity, σac, was found to be increased by annealing and decreased by the replacement of vanadium with Mn4+ or Cr3+ ions. The σac value increased with the measuring frequency ω according to σac(ω)=A(ω)s, where s has a value in the range of 0.33–0.48. Dielectric loss e showed maxima at temperatures depending on the sample composition and the measuring frequency. The magnetic susceptibility χ was found to increase by annealing and by introducing Cr3+ or Mn4+ into glass materials. The results obtained were explained on the basis of a mutual interaction, which is exclusively occurring between double redox pairs during the sample preparation or during the annealing process, to prod...
The effect of increasing the annealing temperature on the CdS incorporated in silica xerogel thin... more The effect of increasing the annealing temperature on the CdS incorporated in silica xerogel thin film glasses is evaluated. The thin film samples are prepared via silica gels containing solution mixture of (CdCl2 and thiourea) with molar ratio 1:1, 5 mol % from this mixture solution was added to the host silica gel precursor. X-ray diffraction and Scanning electron microscope make it possible to evaluate the sample structure and the morphology. The absorption edge exhibited a blue shift by decreasing the annealing temperature, and its energy shift was reciprocally proportional to the radius. The energy band gap shifted upward in energy for smaller nano-particle size.
The glass–ceramic with the composition x(LiFe5O8)/(100 – x) SiO2 (x 20, 30, 40, 50, 100 wt. % )... more The glass–ceramic with the composition x(LiFe5O8)/(100 – x) SiO2 (x 20, 30, 40, 50, 100 wt. % ) were prepared by sol gel auto-combustion method. The influence of the SiO2 ratio in the glass-ceramics strucure prepared was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Crystalline phases (LiFe5O8, SiO2, Fe2O3) were observed by X-ray powder diffraction in the glasses annealed at 800 C for 2h. The crystallite size was found to increase from 27.29 nm (x 20%) to 91.48 nm (x 100 %). The microstructure of the formed powders was SiO2 ratio dependent. Increasing the SiO2 ratio was found to inhibit the grain growth of the formed ferrite. The electrical conductivity of glass-ceramics samples were raised with increasing the concentration of SiO2 ratio as the result of increasing the hopping of electrons between Fe2+ and Fe3+ ions. The magnetic characteristics of the prepared glass ceramics were performed using a vibrating sample magnetometer in function of...
2016 18th International Conference on Transparent Optical Networks (ICTON), 2016
The effect of increasing temperature on the optical, spectroscopic and structural properties of p... more The effect of increasing temperature on the optical, spectroscopic and structural properties of phospho-silicate nano-composites thin films SPNCTF and monolith SPNCM were studied. Doping the mentioned prepared forms of sample with some rare earth oxide such as Neodymium (Nd3+), Erbium (Er3+), Holmium (Ho3+) etc… SPNCRETF and SPNCREM have been prepared. Such materials could be promising for wave guide application, up-down shifting harvesting solar cell and could allow fabricating small devices with high gain in the telecommunication wavelength bands. The X-Ray diffraction XRD phases of the prepared samples deposited on appropriate substrates are analysed. The structural study revealed that the crystallite sizes of monolith and thin film phospho-silicate is in the nano-scale. The photo-luminescence properties have analyzed in the visible wavelength range as a function of sample composition. The optical properties will be studied by measuring the normal transmission and specular reflection, moreover the refractive index of the prepared samples will be calculated.
Abstract: The effect of composition in the ionic glassy system AgI-Ag2O3- Bi2O3-B2O3 on the elect... more Abstract: The effect of composition in the ionic glassy system AgI-Ag2O3- Bi2O3-B2O3 on the electrical properties was investigated. The glasses have been prepared by melt quenching technique. The synthesized materials with up to 40 mol% AgI were formed in amorphous form. Above this value, the materials were only partially amorphous and contained crystalline inclusions, which were identified as AgI. The electrical conductivity (, dielectric constant (ε') and dielectric loss ('') studies of the samples have been carried out at different temperatures and frequencies. The conductivity of the glasses increased with the increase in the AgI content and attains a highest ionic conductivity value with a composition of (AgI)0.3(Ag2O)0.2(Bi2O3)0.25(B2O3)0.25. The electrical data are discussed on the basis of Ag+ diffusion in the glassy structure, which plays a significant role in both conduction and dielectric relaxation processes in the glass matrix. Key words: Ionic conduc...
In a dietary survey, large numbers of a wide variety of food samples have to be analyzed. The ato... more In a dietary survey, large numbers of a wide variety of food samples have to be analyzed. The atomic absorption spectroscopy (AAS), with its simplicity, accuracy and rapidity, suggests itself for determination of many elements in such a case. In this investigation, calcium determination by AAS is reviewed. Analytical parameters, interferences and their control are studied. Food samples are dry ashed and treated so as to eliminate silicates. Most serious interference comes from phosphates and is successfully controlled by addition of lanthanum. Calcium is determined in the range 2-10 ppm with a sensitivity of 0.1 ppm. Single food samples and samples representing food mixtures are analyzed, and calcium intake of different population groups is computed. In most cases, results compare favourably well with those obtained from food composition tables. Calcium intake in the Netherlands both of the average per caput and of chosen population groups is found to cover the recommendations excep...
To evaluate beta-endorphin secretion in euprolactinemic cases of luteal phase defect (LPD). Seria... more To evaluate beta-endorphin secretion in euprolactinemic cases of luteal phase defect (LPD). Serial blood samples from the 18th to the 26th day of the menstrual cycle were assayed for beta-endorphin, progesterone (P), estradiol (E2), and prolactin (PRL) in cases of LPD and controls. Diagnosis of LPD was based on determinations of serum P and premenstrual endometrial biopsy. From Cairo University Hospitals. PATIENT, PARTICIPANTS: Twenty-six women with LPD and 8 normal fertile women (controls) were chosen. None. beta-Endorphin, P, E2, and PRL concentrations were determined by the corresponding 125I radioimmunoassay. Plasma beta-endorphin level in cases of LPD varied from 2.58 to 9.14 pmol/L, whereas the level of controls varied from 2.41 to 5.57 pmol/L. The mean value of plasma beta-endorphin in cases of LPD was significantly higher than that of controls by 146% (P less than 0.0005). In spite of the significant decrease of serum P in cases of LPD, serum E2 level did not differ signific...
ABSTRACT a b s t r a c t In the present study, nano-sized ZnO particle-reinforced Sn–3.0Ag–0.5Cu ... more ABSTRACT a b s t r a c t In the present study, nano-sized ZnO particle-reinforced Sn–3.0Ag–0.5Cu (SAC305) composite solder was prepared by mechanically dispersing nano-particles into SAC305 solder at 900 1C for 2 h. The effects of ZnO addition on microstructure, melting behavior and corresponding mechanical properties of SAC305 solder were explored. Microstructure analysis revealed that the wurtzite ZnO particles were effective in reducing both the β-Sn grain size and spacing between Ag 3 Sn and Cu 6 Sn 5 particles. The refined microstructure, which resulted in a strong adsorption effect and high surface-free energy of ZnO nanoparticles, could obstruct the dislocation slipping, and thus provides classical dispersion strengthen-ing mechanism. This apparently enhances the yield stress (0.2%YS) and ultimate tensile strength (UTS) of SAC(305)–0.7%ZnO composite solder, whereas its ductility is lower than that of the SAC305 solder. In addition, ZnO particles keep the melting temperature of composite solder nearly at the SAC305 level although the pasty range is decreased. Empirical equations for 0.2% YS, UTS and elastic modulus E with the strain rate have been developed and the predicted tensile parameters for both solders are reasonably close to the present experimental data. & 2014 Elsevier B.V. All rights reserved.
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Papers by M. El-Shaarawy