A single and pure CoFe 2 O 4 phase at the nanoscale has been successfully synthesised by a simple... more A single and pure CoFe 2 O 4 phase at the nanoscale has been successfully synthesised by a simple combination of milling a mixture of Fe-oxide and Co-oxide followed by annealing at low temperature, i.e., 750°C. X-ray diffraction and magnetic measurements were carried out.
A mixture of Fe 2 O 3 and Pb 3 O 4 oxides has been mechanically milled to form the nanosized spin... more A mixture of Fe 2 O 3 and Pb 3 O 4 oxides has been mechanically milled to form the nanosized spinel PbFe 2 O 4 phase. X-ray diffraction pattern of the as milled mixture shows the presence of Fe 2 O 3 peaks in addition to a broad halo around 29° related to the amorphisation of Pb3O4. Annealing at 750°C for 1 h, leads to the formation of new phases as evidenced by the appearance of new peaks. The saturation magnetisation and coercivity values of the as-milled mixture are 1.03 emu/g and 200 Oe, respectively. After annealing, a paramagnetic behaviour with a large hysteresis loop was observed.
A mixture of In2O3 + 10% SnO was milled under various conditions, followed by subsequent annealin... more A mixture of In2O3 + 10% SnO was milled under various conditions, followed by subsequent annealing at various temperatures. X-ray diffraction analysis and FTIR measurements were carried out. It is found that after milling, a single (In,Sn)2O3 phase is obtained, indicating the dissolution of Sn into In2O3 lattice and its substitution into In-ionic site.
After completing its sequence/annotation in 2005, Magnetospirillum magneticum AMB-1 had become on... more After completing its sequence/annotation in 2005, Magnetospirillum magneticum AMB-1 had become one of the most important magnetotactic genomes used to facilitate analysis of the magnetosome formation process. In this short report we investigate the genome contents of AMB-1 and other magnetotactic bacteria to illustrate possible functions related to their fitness to a toxic iron oxide environments. The preliminary analysis presented here shows the mosaic structure of these genomes.
International Journal of Materials Engineering Innovation
Silica and titania coated Fe3O4 nanoparticles Fe3O4 (1) -SiO2 and Fe3O4 (2)-TiO2 were prepared us... more Silica and titania coated Fe3O4 nanoparticles Fe3O4 (1) -SiO2 and Fe3O4 (2)-TiO2 were prepared using thermal hydrolysis method. The structure of the core-shell nanostructures was determined by FT-IR and XRD analysis. FT-IR spectra for Fe3O4(1)-SiO2 and Fe3O4(2)-TiO2 show peaks corresponding to the stretching vibrations of Si-O and Ti-O groups, respectively. The surface modification of Fe3O4 nanoparticles with SiO2 or TiO2 did not lead to their phase change as confirmed by XRD diffraction analysis. Additionally, both samples show ferromagnetic behaviour as the saturation magnetisation values for Fe3O4 (1)-SiO2 and Fe3O4 (2)-TiO2 samples decrease by 20% and 33%, respectively with an increase in the shell thickness by 10 nm and 2 nm, respectively.
Magnetic Fe3O4 nanoparticles have been synthesised by two methods: co-precipitation using a range... more Magnetic Fe3O4 nanoparticles have been synthesised by two methods: co-precipitation using a range of Fe3+ and Fe27+ raw materials; oxidative hydrolysis using various Fe2+ salts. X-ray diffraction analysis shows that most of the samples prepared by the co-precipitation method resulted in a mixture of two iron oxide phases (Fe2O3 and Fe3O4) with the presence of impurities (unreacted precursors) while using the oxidative hydrolysis method, Fe3O4 was found to be a major product. Magnetic measurements confirm the results obtained by X-ray diffraction. The sample prepared using FeSO4 as precursor in urea and PEG 200 at 40-50°C for 3 hours (nominated as E2) gives an average crystallites size around 70 nm, a saturation magnetisation Ms = 75 emu/g, a remanence of Mr = 12 emu/g and a coercivity of Hc = 110 kOe, which can be a good candidate for biomedical applications.
Proceedings of SPIE - The International Society for Optical Engineering
Dc conductivity and Hall effect measurements were performed on Cu-GeO2 thin films with the aim of... more Dc conductivity and Hall effect measurements were performed on Cu-GeO2 thin films with the aim of obtaining information about dc conduction mechanism. The conductivity results reveal that the activation energy is temperature dependent, increasing significantly above a btransition temperature Tt. Hall mobility showed a sign reversal around Tt, above which it increased with increasing temperature reaching a maximum at a critical temperature Tc. Above Tt, the conductivity is best described by small polaron hopping model. Below Tt, the Hall mobility shows a significant rise with decreasing temperature, indicating polaronic band conduction mechanism. Various parameters associated with polaronic formation are calculated.
AC electrical properties of 410 nm thick 30 at.wt% Cu-70 at.wt% GeO 2 thin films are reported for... more AC electrical properties of 410 nm thick 30 at.wt% Cu-70 at.wt% GeO 2 thin films are reported for the frequency range 10 4 to 10 6 Hz and temperature range 150 to 425 K. The loss tangent (tan δ) and the dielectric loss (/ 0) are found to show striking minima around a cutoff frequency ∼10 5 Hz. In the lower frequency range (≤10 5 Hz), σ 1 (ω) ∝ ω s T n is obeyed with s (0 to 0.51) increasing as a function of temperature and n (0.10 to 0.14) showing a very weak temperature dependence. In the higher frequency region (≥10 5 Hz), σ 1 (ω) and / 0 increase sharply leading to the quadratic behavior of σ 1 (ω) with s equal to 2. These processes are discussed by analyzing an equivalent circuit which shows that at lower frequencies, the effects of series resistance in leads and contacts can be neglected, while at higher frequencies such effect give rise to spurious ω 2 dependance for the conductance. A weakly activated AC conductivity and a frequency exponent s that increases with increasing temperature suggest that the low frequency behavior originates from carrier migration by tunneling process.
Journal of the Association of Arab Universities for Basic and Applied Sciences, 2014
Rashdan (2015) Evaluation of the mobile content in Magnetospirillum magneticum AMB-1 genome using... more Rashdan (2015) Evaluation of the mobile content in Magnetospirillum magneticum AMB-1 genome using bioinformatical approaches reveals a new genome size for the magnetosome island,
ZnCr 1-x Fe x O 4 system (with x = 0, 0.5, 1, 1.5, and 2) at the nanoscale has been successfully ... more ZnCr 1-x Fe x O 4 system (with x = 0, 0.5, 1, 1.5, and 2) at the nanoscale has been successfully synthesized by a simple combination of milling mixture of Zn , Cr , and Fe oxides precursors. X-ray diffraction and magnetic measurements were carried out on the as-milled powders. XRD pattern clearly shows that the mixed oxides are all nanosized. However, as Fe 2 O 3 increases the ZnCrFeO 4 phase becomes the main phase. However, magnetic measurements do not show any significance in saturation magnetization (Ms), only when the content of Fe becomes 50% and 0.75% the Ms increased drastically to 15.4 and 16.7 emu/g respectively. However, with Fe 75% He and Mr reduced abruptly to half of their values, showing a ferromagnetic behaviour with low He .
A mixture of Fe 2 O 3 and SnO oxides has been mechanically milled to form SnFe 2 O 4 spinel phase... more A mixture of Fe 2 O 3 and SnO oxides has been mechanically milled to form SnFe 2 O 4 spinel phase. X-ray diffraction pattern of the milled mixture shows that after milling, both peaks of Fe 2 O 3 and SnO remain with a drastic decrease of their intensities and broadening. The appearance of a broad halo around 2θ ~ 31° indicates the formation of an amorphous phase. After annealing at 750°C for 1 h, SnO peaks disappear completely and new diffraction peaks emerge indicating the formation of a new nanophase i.e. SnO 2. Magnetic measurements of the as-milled mixture show a ferromagnetic behavior with saturation magnetization Ms = 6.8 emu/g which drastically decreases after annealing to 0.6 emu/g.
The crystalline semiconductor material (MnPS3) has interlayer d-spacing gap of 6.4 Å. The main ad... more The crystalline semiconductor material (MnPS3) has interlayer d-spacing gap of 6.4 Å. The main advantage of this gap is the ability to accommodate organic and inorganic compounds. Pyridine was intercalated in the MnPS3 interlayer gap under specific conditions. Four phases (d-spacing = 12.48 Å, 10.8 Å, 9.7 Å and 7.3 Å) were observed and the corresponding lattice expansions were determined, 5.8 Å, 4.4 Å, 3.3 Å and 1 Å, respectively. X-ray diffraction patterns of the samples after the experiment were stopped to reveal the presence of three phases together. The phase transformation occurred for the aforementioned phases. The crystallite size of certain phases is within nanorange. The magnetic properties of the materials are affected by the phase transformation. Complete intercalation was confirmed by the XRD and infrared (IR) measurements.
ABSTRACT A clean route for oxide scale grown on low carbon steel alloy surface at 650°C under con... more ABSTRACT A clean route for oxide scale grown on low carbon steel alloy surface at 650°C under controlled heating rate and oxidation period, was investigated. It was found that using controlled conditions of a certain heating rate and an oxidation time led to remarkable changes in the formation of the oxide scale phases and the crystallites size. X-ray diffraction patterns show the formation of α-Fe<sub align="right"> 2 O<sub align="right"> 3 and Fe<sub align="right"> 3 O<sub align="right"> 4 phases with some preferred orientation in the (100) direction. The estimated average crystallites size of the oxide scale is about 30 nm after 60 hours of oxidation time at 650°C under constant heating rate of 0.1°C/min. Increasing the oxidation time slightly increases the crystallite size. The oxide scale exhibited a relatively medium saturation magnetisation of 34.59 emu/g. This indicates the presence of mixture of Fe oxides, predominately α-Fe<sub align="right"> 2 O<sub align="right"> 3 and Fe<sub align="right"> 3 O<sub align="right"> 4 phases, as observed in the X-ray diffraction patterns.
ABSTRACT Dc conductivity, Hall effect, and optical absorption measurements were performed on Cu-G... more ABSTRACT Dc conductivity, Hall effect, and optical absorption measurements were performed on Cu-GeO2 thin films to elucidate the dc conduction mechanism. The dc activation energy is temperature dependent, increasing significantly above a transition temperature Tt. Hall mobility exhibited a sign reversal around Tt, above which it increased to a maximum value at a critical temperature Tc. The almost identical transition temperatures in conductivity and Hall mobility suggest that the conductivity results from a combination of two processes. Above Tt, the conductivity is best described by small polaron phonon-assisted hopping model; hopping appears to be non-adiabatic in nature. Below Tt, the conductivity is weakly activated, magnetoresistance is negative, and the Hall mobility shows a significant rise with decreasing temperature. These are features which suggest non-polaronic thermally activated hopping through a spectrum of localized states. Various parameters associated with polaron formation are calculated.
ABSTRACT The ion beam mixing of Au thin film evaporated on silicon is investigated by measuring c... more ABSTRACT The ion beam mixing of Au thin film evaporated on silicon is investigated by measuring continuously the electrical resistivity of the sample during Kr ion irradiation. Rutherford backscattering spectra measurements with 2.0 MeV He ions are measured after beam irradiation. The resistivity results exhibit a tendency toward saturation and allow the determination of the critical dose corresponding to the total mixing condition. The variation in the normalized conductivity, due to the intermixed atoms as a function of the ion dose are deduced and compared with a semiempirical formula to explain the observed mixing kinetics. The mixing results are confirmed with the RBS measurements.Es wird die Ionenstrahlmischung von dünnen auf Silizium aufgebrachten Au-Schichten untersucht, indem der elektrische Widerstand der Probe kontinuierlich während der Kr-Ionenbestrahlung gemessen wird. Rutherford-Rückstreuspektren mit 2.0 MeV-He-Ionen werden nach Bestrahlung gemessen. Die Widerstandswerte zeigen eine Tendenz zur Sättigung und erlauben die Bestimmung der kritischen Dosis, die der Bedingung vollständiger Mischung entspricht. Die Änderung in der normierten Leitfähigkeit infolge der gemischten Atome werden als Funktion der Ionendosis bestimmt und mit einer halbempirischen Formel verglichen, um die beobachtete Mischkinetik zu erklären. Die Mischungs ergebnisse werden durch die RBS-Messungen bestätigt.
A single and pure CoFe 2 O 4 phase at the nanoscale has been successfully synthesised by a simple... more A single and pure CoFe 2 O 4 phase at the nanoscale has been successfully synthesised by a simple combination of milling a mixture of Fe-oxide and Co-oxide followed by annealing at low temperature, i.e., 750°C. X-ray diffraction and magnetic measurements were carried out.
A mixture of Fe 2 O 3 and Pb 3 O 4 oxides has been mechanically milled to form the nanosized spin... more A mixture of Fe 2 O 3 and Pb 3 O 4 oxides has been mechanically milled to form the nanosized spinel PbFe 2 O 4 phase. X-ray diffraction pattern of the as milled mixture shows the presence of Fe 2 O 3 peaks in addition to a broad halo around 29° related to the amorphisation of Pb3O4. Annealing at 750°C for 1 h, leads to the formation of new phases as evidenced by the appearance of new peaks. The saturation magnetisation and coercivity values of the as-milled mixture are 1.03 emu/g and 200 Oe, respectively. After annealing, a paramagnetic behaviour with a large hysteresis loop was observed.
A mixture of In2O3 + 10% SnO was milled under various conditions, followed by subsequent annealin... more A mixture of In2O3 + 10% SnO was milled under various conditions, followed by subsequent annealing at various temperatures. X-ray diffraction analysis and FTIR measurements were carried out. It is found that after milling, a single (In,Sn)2O3 phase is obtained, indicating the dissolution of Sn into In2O3 lattice and its substitution into In-ionic site.
After completing its sequence/annotation in 2005, Magnetospirillum magneticum AMB-1 had become on... more After completing its sequence/annotation in 2005, Magnetospirillum magneticum AMB-1 had become one of the most important magnetotactic genomes used to facilitate analysis of the magnetosome formation process. In this short report we investigate the genome contents of AMB-1 and other magnetotactic bacteria to illustrate possible functions related to their fitness to a toxic iron oxide environments. The preliminary analysis presented here shows the mosaic structure of these genomes.
International Journal of Materials Engineering Innovation
Silica and titania coated Fe3O4 nanoparticles Fe3O4 (1) -SiO2 and Fe3O4 (2)-TiO2 were prepared us... more Silica and titania coated Fe3O4 nanoparticles Fe3O4 (1) -SiO2 and Fe3O4 (2)-TiO2 were prepared using thermal hydrolysis method. The structure of the core-shell nanostructures was determined by FT-IR and XRD analysis. FT-IR spectra for Fe3O4(1)-SiO2 and Fe3O4(2)-TiO2 show peaks corresponding to the stretching vibrations of Si-O and Ti-O groups, respectively. The surface modification of Fe3O4 nanoparticles with SiO2 or TiO2 did not lead to their phase change as confirmed by XRD diffraction analysis. Additionally, both samples show ferromagnetic behaviour as the saturation magnetisation values for Fe3O4 (1)-SiO2 and Fe3O4 (2)-TiO2 samples decrease by 20% and 33%, respectively with an increase in the shell thickness by 10 nm and 2 nm, respectively.
Magnetic Fe3O4 nanoparticles have been synthesised by two methods: co-precipitation using a range... more Magnetic Fe3O4 nanoparticles have been synthesised by two methods: co-precipitation using a range of Fe3+ and Fe27+ raw materials; oxidative hydrolysis using various Fe2+ salts. X-ray diffraction analysis shows that most of the samples prepared by the co-precipitation method resulted in a mixture of two iron oxide phases (Fe2O3 and Fe3O4) with the presence of impurities (unreacted precursors) while using the oxidative hydrolysis method, Fe3O4 was found to be a major product. Magnetic measurements confirm the results obtained by X-ray diffraction. The sample prepared using FeSO4 as precursor in urea and PEG 200 at 40-50°C for 3 hours (nominated as E2) gives an average crystallites size around 70 nm, a saturation magnetisation Ms = 75 emu/g, a remanence of Mr = 12 emu/g and a coercivity of Hc = 110 kOe, which can be a good candidate for biomedical applications.
Proceedings of SPIE - The International Society for Optical Engineering
Dc conductivity and Hall effect measurements were performed on Cu-GeO2 thin films with the aim of... more Dc conductivity and Hall effect measurements were performed on Cu-GeO2 thin films with the aim of obtaining information about dc conduction mechanism. The conductivity results reveal that the activation energy is temperature dependent, increasing significantly above a btransition temperature Tt. Hall mobility showed a sign reversal around Tt, above which it increased with increasing temperature reaching a maximum at a critical temperature Tc. Above Tt, the conductivity is best described by small polaron hopping model. Below Tt, the Hall mobility shows a significant rise with decreasing temperature, indicating polaronic band conduction mechanism. Various parameters associated with polaronic formation are calculated.
AC electrical properties of 410 nm thick 30 at.wt% Cu-70 at.wt% GeO 2 thin films are reported for... more AC electrical properties of 410 nm thick 30 at.wt% Cu-70 at.wt% GeO 2 thin films are reported for the frequency range 10 4 to 10 6 Hz and temperature range 150 to 425 K. The loss tangent (tan δ) and the dielectric loss (/ 0) are found to show striking minima around a cutoff frequency ∼10 5 Hz. In the lower frequency range (≤10 5 Hz), σ 1 (ω) ∝ ω s T n is obeyed with s (0 to 0.51) increasing as a function of temperature and n (0.10 to 0.14) showing a very weak temperature dependence. In the higher frequency region (≥10 5 Hz), σ 1 (ω) and / 0 increase sharply leading to the quadratic behavior of σ 1 (ω) with s equal to 2. These processes are discussed by analyzing an equivalent circuit which shows that at lower frequencies, the effects of series resistance in leads and contacts can be neglected, while at higher frequencies such effect give rise to spurious ω 2 dependance for the conductance. A weakly activated AC conductivity and a frequency exponent s that increases with increasing temperature suggest that the low frequency behavior originates from carrier migration by tunneling process.
Journal of the Association of Arab Universities for Basic and Applied Sciences, 2014
Rashdan (2015) Evaluation of the mobile content in Magnetospirillum magneticum AMB-1 genome using... more Rashdan (2015) Evaluation of the mobile content in Magnetospirillum magneticum AMB-1 genome using bioinformatical approaches reveals a new genome size for the magnetosome island,
ZnCr 1-x Fe x O 4 system (with x = 0, 0.5, 1, 1.5, and 2) at the nanoscale has been successfully ... more ZnCr 1-x Fe x O 4 system (with x = 0, 0.5, 1, 1.5, and 2) at the nanoscale has been successfully synthesized by a simple combination of milling mixture of Zn , Cr , and Fe oxides precursors. X-ray diffraction and magnetic measurements were carried out on the as-milled powders. XRD pattern clearly shows that the mixed oxides are all nanosized. However, as Fe 2 O 3 increases the ZnCrFeO 4 phase becomes the main phase. However, magnetic measurements do not show any significance in saturation magnetization (Ms), only when the content of Fe becomes 50% and 0.75% the Ms increased drastically to 15.4 and 16.7 emu/g respectively. However, with Fe 75% He and Mr reduced abruptly to half of their values, showing a ferromagnetic behaviour with low He .
A mixture of Fe 2 O 3 and SnO oxides has been mechanically milled to form SnFe 2 O 4 spinel phase... more A mixture of Fe 2 O 3 and SnO oxides has been mechanically milled to form SnFe 2 O 4 spinel phase. X-ray diffraction pattern of the milled mixture shows that after milling, both peaks of Fe 2 O 3 and SnO remain with a drastic decrease of their intensities and broadening. The appearance of a broad halo around 2θ ~ 31° indicates the formation of an amorphous phase. After annealing at 750°C for 1 h, SnO peaks disappear completely and new diffraction peaks emerge indicating the formation of a new nanophase i.e. SnO 2. Magnetic measurements of the as-milled mixture show a ferromagnetic behavior with saturation magnetization Ms = 6.8 emu/g which drastically decreases after annealing to 0.6 emu/g.
The crystalline semiconductor material (MnPS3) has interlayer d-spacing gap of 6.4 Å. The main ad... more The crystalline semiconductor material (MnPS3) has interlayer d-spacing gap of 6.4 Å. The main advantage of this gap is the ability to accommodate organic and inorganic compounds. Pyridine was intercalated in the MnPS3 interlayer gap under specific conditions. Four phases (d-spacing = 12.48 Å, 10.8 Å, 9.7 Å and 7.3 Å) were observed and the corresponding lattice expansions were determined, 5.8 Å, 4.4 Å, 3.3 Å and 1 Å, respectively. X-ray diffraction patterns of the samples after the experiment were stopped to reveal the presence of three phases together. The phase transformation occurred for the aforementioned phases. The crystallite size of certain phases is within nanorange. The magnetic properties of the materials are affected by the phase transformation. Complete intercalation was confirmed by the XRD and infrared (IR) measurements.
ABSTRACT A clean route for oxide scale grown on low carbon steel alloy surface at 650°C under con... more ABSTRACT A clean route for oxide scale grown on low carbon steel alloy surface at 650°C under controlled heating rate and oxidation period, was investigated. It was found that using controlled conditions of a certain heating rate and an oxidation time led to remarkable changes in the formation of the oxide scale phases and the crystallites size. X-ray diffraction patterns show the formation of α-Fe<sub align="right"> 2 O<sub align="right"> 3 and Fe<sub align="right"> 3 O<sub align="right"> 4 phases with some preferred orientation in the (100) direction. The estimated average crystallites size of the oxide scale is about 30 nm after 60 hours of oxidation time at 650°C under constant heating rate of 0.1°C/min. Increasing the oxidation time slightly increases the crystallite size. The oxide scale exhibited a relatively medium saturation magnetisation of 34.59 emu/g. This indicates the presence of mixture of Fe oxides, predominately α-Fe<sub align="right"> 2 O<sub align="right"> 3 and Fe<sub align="right"> 3 O<sub align="right"> 4 phases, as observed in the X-ray diffraction patterns.
ABSTRACT Dc conductivity, Hall effect, and optical absorption measurements were performed on Cu-G... more ABSTRACT Dc conductivity, Hall effect, and optical absorption measurements were performed on Cu-GeO2 thin films to elucidate the dc conduction mechanism. The dc activation energy is temperature dependent, increasing significantly above a transition temperature Tt. Hall mobility exhibited a sign reversal around Tt, above which it increased to a maximum value at a critical temperature Tc. The almost identical transition temperatures in conductivity and Hall mobility suggest that the conductivity results from a combination of two processes. Above Tt, the conductivity is best described by small polaron phonon-assisted hopping model; hopping appears to be non-adiabatic in nature. Below Tt, the conductivity is weakly activated, magnetoresistance is negative, and the Hall mobility shows a significant rise with decreasing temperature. These are features which suggest non-polaronic thermally activated hopping through a spectrum of localized states. Various parameters associated with polaron formation are calculated.
ABSTRACT The ion beam mixing of Au thin film evaporated on silicon is investigated by measuring c... more ABSTRACT The ion beam mixing of Au thin film evaporated on silicon is investigated by measuring continuously the electrical resistivity of the sample during Kr ion irradiation. Rutherford backscattering spectra measurements with 2.0 MeV He ions are measured after beam irradiation. The resistivity results exhibit a tendency toward saturation and allow the determination of the critical dose corresponding to the total mixing condition. The variation in the normalized conductivity, due to the intermixed atoms as a function of the ion dose are deduced and compared with a semiempirical formula to explain the observed mixing kinetics. The mixing results are confirmed with the RBS measurements.Es wird die Ionenstrahlmischung von dünnen auf Silizium aufgebrachten Au-Schichten untersucht, indem der elektrische Widerstand der Probe kontinuierlich während der Kr-Ionenbestrahlung gemessen wird. Rutherford-Rückstreuspektren mit 2.0 MeV-He-Ionen werden nach Bestrahlung gemessen. Die Widerstandswerte zeigen eine Tendenz zur Sättigung und erlauben die Bestimmung der kritischen Dosis, die der Bedingung vollständiger Mischung entspricht. Die Änderung in der normierten Leitfähigkeit infolge der gemischten Atome werden als Funktion der Ionendosis bestimmt und mit einer halbempirischen Formel verglichen, um die beobachtete Mischkinetik zu erklären. Die Mischungs ergebnisse werden durch die RBS-Messungen bestätigt.
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Papers by Ahmed Al-Saie