Journal of Materials Science: Materials in Electronics, 2006
DC-magnetization measurements on Fe 0.6-Cr 0.1 Al 0.3 and Fe 0.6 Ti 0.1 Al 0.3 reveals the disapp... more DC-magnetization measurements on Fe 0.6-Cr 0.1 Al 0.3 and Fe 0.6 Ti 0.1 Al 0.3 reveals the disappearance of the wide ferromagnetic state exists in the free doped Fe 0.7 Al 0.3 alloy. Our data shows that the spin glass transition temperature for Fe 0.6 Cr 0.1 Al 0.3 alloy is 38 K and for Fe 0.6 Ti 0.1 Al 0.3 alloy is 41 K. These values are below 70 K which is the spin transition temperature of the Fe 0.7 Al 0.3 alloy. This is attributed to the paramagnetic nature of the metals Cr and Ti.
A structure-independent formulation developed e~rlier for liquid metals is extended to the Ashcro... more A structure-independent formulation developed e~rlier for liquid metals is extended to the Ashcroft's empty core pseudopotential. It is then applied to the ealculatiorm of compressibi]Jty for sixteen liquid metals at melting temperature. The agreement with experimental data is, in general, satisfactory expect for metals having fluctuating valence.
A structure-independent theory for liquid metals is developed on the baais of simplifled Heine-Ab... more A structure-independent theory for liquid metals is developed on the baais of simplifled Heine-Abarenkov electron-ion pseudopotential. The formulation is applied to predict the cohesive energy of sixteen liquid metals. The agreement with the experimental data is, in general, exceedingly good except for metals having fluctuating valence.
The elastic and thermodynamic properties of meta]lic glasses (Ca•0 Mga0, MgT0 Zna0, CusTZr4a and ... more The elastic and thermodynamic properties of meta]lic glasses (Ca•0 Mga0, MgT0 Zna0, CusTZr4a and Pd77.sSi16.sCus) are obtained from dispersion relations in the low momentum region derived by us for various dielectric screenings, adopting a simple model given by Bhatia and Singh. This model assumes a central force, effective between nearest neighbours and a volume dependent force. For elastic properties, elastic constants C11 and C44 are obtained from slopes of longitudinal and transverse dispersion relations, respectively, whereas C12 is found by the requirement that elastic anisotropy for disordered systems, like metallic glass, is to be zero. For thermodynamic properties, Debye temperature is calculated for the glasses for vaxious dielectric screenings.
The phonon frequencies of longitudinal and transverse waves for metallic glasses are derived and ... more The phonon frequencies of longitudinal and transverse waves for metallic glasses are derived and computed for ternary Pd77.5Si16.5Cu6 glasses. The dispersion of phonon frequency with respect to the wavenumber is found to be influenced by the dielectric screening due to conduction electrons.
Abstract. The design and slicing technique of artificial soft tissue are presented. Artificial so... more Abstract. The design and slicing technique of artificial soft tissue are presented. Artificial soft tissue has optical penetration properties similar to biological tissues. The soft tissues are made of agar dissolved in water as a transparent tissue (control) in-corporated with scatter ...
Specimens of Tl2Ba2Ca2Cu3O10 tapes were prepared using the powder in tube method. The voltage-cur... more Specimens of Tl2Ba2Ca2Cu3O10 tapes were prepared using the powder in tube method. The voltage-current (V - I ) characteristics were used to study the temperature and magnetic field dependence of the critical current density Jc(T,B). Obtained results confirmed the high sensitivity of the superconducting tape to the applied magnetic field and are explained based on the weak links and Josephson
Magnetization vector measurements were carried out in a polycrystalline sample of Tl-2223 superco... more Magnetization vector measurements were carried out in a polycrystalline sample of Tl-2223 superconductor in fixed fields at low temperatures. Demonstrating the broad distribution in the vortex flux pinning, the vortex flux density B was seen to consist of two component: the rotational component BR turns rigidly with sample rotation and the frictional component BF stays at fixed angle thetaF relative
Specimens of Tl1Ba2Ca2Cu3O9 superconducting tapes (Tl-1223) have been prepared using the powder-i... more Specimens of Tl1Ba2Ca2Cu3O9 superconducting tapes (Tl-1223) have been prepared using the powder-in-tube (PIT) method. Dissipative mechanisms and power law behavior were investigated using magnetoresistance measurements and I-V characteristics. The temperature and magnetic field dependences of the resistance R(T,B) were fitted to the Arrhenius relation from which the magnetic field dependence of the pinning energy U0(B) was derived. The I-V data
Expressions for the phonon frequencies of the binary and ternary metallic glasses are derived on ... more Expressions for the phonon frequencies of the binary and ternary metallic glasses are derived on the basis of various dielectric screenings. A model which assumes a central force, effective between nearest neighbours, and a volume dependent force is adopted. The phonon frequencies of longitudinal and transverse phonons for the binary metallic glasses Ca70Mg,o, Mg,,Zn,,, and CuS7Zr4, and for the ternary metallic glass Pd,,,,Si,,,,Cu, are computed. The theoretical results compared with experimental data underline the importance of dielectric screening by conduction electrons. I ) Jaipur 302004, India. ' ) Irbid, Jordan.
X-ray diffraction patterns of Nd 2 Fe 15 Ga 2 C x (0pxp2) show that all the alloys studied have t... more X-ray diffraction patterns of Nd 2 Fe 15 Ga 2 C x (0pxp2) show that all the alloys studied have the Th 2 Zn 17 rhombohederal structure. The lattice parameters and the unit cell volume are found to increase linearly with increasing carbon concentration. Structural measurements on magnetically aligned powder samples show that the samples studied possess magnetic anisotropy with a basal easy axis. Magnetization measurements at 5 K and at room temperature show that all samples under investigation are ferromagnetic, and the saturation magnetization increases with increasing x; reaching a maximum at x ¼ 1; and then decreases slowly for larger values of x: M .
Specimens of polycrystalline Tl 1 Ba 2 Ca 2 Cu 3 O y superconductor (Tl-1223) have been irradiate... more Specimens of polycrystalline Tl 1 Ba 2 Ca 2 Cu 3 O y superconductor (Tl-1223) have been irradiated at room temperature by g-rays. The variations of the normal state resistance, transition width and the critical current densities with girradiation up to about 400 MR were studied. The normal state resistivity rðTÞ increases gradually up to a dose of 100 MR, whereas at higher doses, the effect of irradiation becomes rather negligible. The transition temperature T c decreases slightly and the transition temperature width DT broadens at doses below 100 MR with almost no change at higher doses up to 400 MR. At relatively low temperatures and low g-doses, the critical current densities J c ðTÞ increase with g-irradiation, while the effect of g-irradiation at temperatures very close to T c is rather negligible. Obtained results confirmed the high sensitivity of (Tl-1223) superconductor to g-irradiation at relatively low g-doses. These results are discussed and explained in terms of the effect of g-rays on the weak links and Josephson junctions between the grains. r
Polycrystalline samples of Y 1Àx Gd x Ba 2 Cu 3 O 7 with different Gd contents (x ¼ 1; 0:75; 0:5;... more Polycrystalline samples of Y 1Àx Gd x Ba 2 Cu 3 O 7 with different Gd contents (x ¼ 1; 0:75; 0:5; 0:25) were prepared using the usual solid state reaction method. X-ray characterization of these samples showed an orthorhombic phase. The lattice parameters a; b; and c were found to increase with increasing Gd concentration which is due to the larger volume of Gd atoms. Magnetization and transport measurements show the same transition temperature of 91 K for all samples studied. Initial and magnetization hysteresis loop measurements showed that the paramagnetic behavior is dominant at high fields. r
Journal of Superconductivity and Novel Magnetism, 2010
Series of (YBa 2 Cu 3 O 7−δ ) 1−x (Al 2 O 3 ) x samples have been prepared using solid state reac... more Series of (YBa 2 Cu 3 O 7−δ ) 1−x (Al 2 O 3 ) x samples have been prepared using solid state reaction method. Various amount of nano-sized Al 2 O 3 particles (∼50 nm) were added with (x = 0, 0.005, 0.01, 0.02, and 0.05). The microstructure and the morphology of the polycrystalline samples have been characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). The magnetotransport properties of these samples were investigated using resistance-temperature (R-T ) and current-voltage (I -V ) characteristics. All samples showed an orthorhombic structure with a tendency to transformation to tetragonal phase at higher levels of nanoparticles addition. The morphology of the surface of pure samples reveals a considerable number of weak-links, randomly oriented and clean grain boundaries. While in samples with nano inclusions, grain boundaries were filled with nanosized particle and have less number of weak-links. Significant enhancement of the superconducting critical current density J c in applied magnetic field was observed due to nano Al 2 O 3 inclusions. However, further increase in the value of x decreases the transition temperature T c and the critical current density J c . These results were interpreted in terms of the flux pinning mechanisms in granular superconducting networks which leads to a better basic understanding of the performance of YBCO system in high applied magnetic fields.
Magnetization measurements on zero field cooled (ZFC) and field cooled (FC) samples as a function... more Magnetization measurements on zero field cooled (ZFC) and field cooled (FC) samples as a function of temperature where made on Fe Mn Al alloys with 0#x#0.10. Our data show the existence of two regimes of the spin glass temperature T when increasing 0.702x x 0.30 f the concentration x of the Mn atoms. We found that T decreases slowly with increasing x up to x50.06 and then shows a rapid linear f decrease above this concentration. The existence of two regimes of T behavior with x may be attributed to the disappearance of f ferromagnetic clusters which exist for low values of x (x,0.06). Compared to the Mn-free alloy, the relative changes in T are bigger and f exceed 40% at x50.10. The second regime (x.0.06) is associated with more influence of x on T .
We report the structural and magnetic properties of GdFe Ti alloys, where x50, 0.05, 0.10, 0.15, ... more We report the structural and magnetic properties of GdFe Ti alloys, where x50, 0.05, 0.10, 0.15, 0.20, 0.30. X-ray diffraction shows 22x
Journal of Materials Science: Materials in Electronics, 2006
DC-magnetization measurements on Fe 0.6-Cr 0.1 Al 0.3 and Fe 0.6 Ti 0.1 Al 0.3 reveals the disapp... more DC-magnetization measurements on Fe 0.6-Cr 0.1 Al 0.3 and Fe 0.6 Ti 0.1 Al 0.3 reveals the disappearance of the wide ferromagnetic state exists in the free doped Fe 0.7 Al 0.3 alloy. Our data shows that the spin glass transition temperature for Fe 0.6 Cr 0.1 Al 0.3 alloy is 38 K and for Fe 0.6 Ti 0.1 Al 0.3 alloy is 41 K. These values are below 70 K which is the spin transition temperature of the Fe 0.7 Al 0.3 alloy. This is attributed to the paramagnetic nature of the metals Cr and Ti.
A structure-independent formulation developed e~rlier for liquid metals is extended to the Ashcro... more A structure-independent formulation developed e~rlier for liquid metals is extended to the Ashcroft's empty core pseudopotential. It is then applied to the ealculatiorm of compressibi]Jty for sixteen liquid metals at melting temperature. The agreement with experimental data is, in general, satisfactory expect for metals having fluctuating valence.
A structure-independent theory for liquid metals is developed on the baais of simplifled Heine-Ab... more A structure-independent theory for liquid metals is developed on the baais of simplifled Heine-Abarenkov electron-ion pseudopotential. The formulation is applied to predict the cohesive energy of sixteen liquid metals. The agreement with the experimental data is, in general, exceedingly good except for metals having fluctuating valence.
The elastic and thermodynamic properties of meta]lic glasses (Ca•0 Mga0, MgT0 Zna0, CusTZr4a and ... more The elastic and thermodynamic properties of meta]lic glasses (Ca•0 Mga0, MgT0 Zna0, CusTZr4a and Pd77.sSi16.sCus) are obtained from dispersion relations in the low momentum region derived by us for various dielectric screenings, adopting a simple model given by Bhatia and Singh. This model assumes a central force, effective between nearest neighbours and a volume dependent force. For elastic properties, elastic constants C11 and C44 are obtained from slopes of longitudinal and transverse dispersion relations, respectively, whereas C12 is found by the requirement that elastic anisotropy for disordered systems, like metallic glass, is to be zero. For thermodynamic properties, Debye temperature is calculated for the glasses for vaxious dielectric screenings.
The phonon frequencies of longitudinal and transverse waves for metallic glasses are derived and ... more The phonon frequencies of longitudinal and transverse waves for metallic glasses are derived and computed for ternary Pd77.5Si16.5Cu6 glasses. The dispersion of phonon frequency with respect to the wavenumber is found to be influenced by the dielectric screening due to conduction electrons.
Abstract. The design and slicing technique of artificial soft tissue are presented. Artificial so... more Abstract. The design and slicing technique of artificial soft tissue are presented. Artificial soft tissue has optical penetration properties similar to biological tissues. The soft tissues are made of agar dissolved in water as a transparent tissue (control) in-corporated with scatter ...
Specimens of Tl2Ba2Ca2Cu3O10 tapes were prepared using the powder in tube method. The voltage-cur... more Specimens of Tl2Ba2Ca2Cu3O10 tapes were prepared using the powder in tube method. The voltage-current (V - I ) characteristics were used to study the temperature and magnetic field dependence of the critical current density Jc(T,B). Obtained results confirmed the high sensitivity of the superconducting tape to the applied magnetic field and are explained based on the weak links and Josephson
Magnetization vector measurements were carried out in a polycrystalline sample of Tl-2223 superco... more Magnetization vector measurements were carried out in a polycrystalline sample of Tl-2223 superconductor in fixed fields at low temperatures. Demonstrating the broad distribution in the vortex flux pinning, the vortex flux density B was seen to consist of two component: the rotational component BR turns rigidly with sample rotation and the frictional component BF stays at fixed angle thetaF relative
Specimens of Tl1Ba2Ca2Cu3O9 superconducting tapes (Tl-1223) have been prepared using the powder-i... more Specimens of Tl1Ba2Ca2Cu3O9 superconducting tapes (Tl-1223) have been prepared using the powder-in-tube (PIT) method. Dissipative mechanisms and power law behavior were investigated using magnetoresistance measurements and I-V characteristics. The temperature and magnetic field dependences of the resistance R(T,B) were fitted to the Arrhenius relation from which the magnetic field dependence of the pinning energy U0(B) was derived. The I-V data
Expressions for the phonon frequencies of the binary and ternary metallic glasses are derived on ... more Expressions for the phonon frequencies of the binary and ternary metallic glasses are derived on the basis of various dielectric screenings. A model which assumes a central force, effective between nearest neighbours, and a volume dependent force is adopted. The phonon frequencies of longitudinal and transverse phonons for the binary metallic glasses Ca70Mg,o, Mg,,Zn,,, and CuS7Zr4, and for the ternary metallic glass Pd,,,,Si,,,,Cu, are computed. The theoretical results compared with experimental data underline the importance of dielectric screening by conduction electrons. I ) Jaipur 302004, India. ' ) Irbid, Jordan.
X-ray diffraction patterns of Nd 2 Fe 15 Ga 2 C x (0pxp2) show that all the alloys studied have t... more X-ray diffraction patterns of Nd 2 Fe 15 Ga 2 C x (0pxp2) show that all the alloys studied have the Th 2 Zn 17 rhombohederal structure. The lattice parameters and the unit cell volume are found to increase linearly with increasing carbon concentration. Structural measurements on magnetically aligned powder samples show that the samples studied possess magnetic anisotropy with a basal easy axis. Magnetization measurements at 5 K and at room temperature show that all samples under investigation are ferromagnetic, and the saturation magnetization increases with increasing x; reaching a maximum at x ¼ 1; and then decreases slowly for larger values of x: M .
Specimens of polycrystalline Tl 1 Ba 2 Ca 2 Cu 3 O y superconductor (Tl-1223) have been irradiate... more Specimens of polycrystalline Tl 1 Ba 2 Ca 2 Cu 3 O y superconductor (Tl-1223) have been irradiated at room temperature by g-rays. The variations of the normal state resistance, transition width and the critical current densities with girradiation up to about 400 MR were studied. The normal state resistivity rðTÞ increases gradually up to a dose of 100 MR, whereas at higher doses, the effect of irradiation becomes rather negligible. The transition temperature T c decreases slightly and the transition temperature width DT broadens at doses below 100 MR with almost no change at higher doses up to 400 MR. At relatively low temperatures and low g-doses, the critical current densities J c ðTÞ increase with g-irradiation, while the effect of g-irradiation at temperatures very close to T c is rather negligible. Obtained results confirmed the high sensitivity of (Tl-1223) superconductor to g-irradiation at relatively low g-doses. These results are discussed and explained in terms of the effect of g-rays on the weak links and Josephson junctions between the grains. r
Polycrystalline samples of Y 1Àx Gd x Ba 2 Cu 3 O 7 with different Gd contents (x ¼ 1; 0:75; 0:5;... more Polycrystalline samples of Y 1Àx Gd x Ba 2 Cu 3 O 7 with different Gd contents (x ¼ 1; 0:75; 0:5; 0:25) were prepared using the usual solid state reaction method. X-ray characterization of these samples showed an orthorhombic phase. The lattice parameters a; b; and c were found to increase with increasing Gd concentration which is due to the larger volume of Gd atoms. Magnetization and transport measurements show the same transition temperature of 91 K for all samples studied. Initial and magnetization hysteresis loop measurements showed that the paramagnetic behavior is dominant at high fields. r
Journal of Superconductivity and Novel Magnetism, 2010
Series of (YBa 2 Cu 3 O 7−δ ) 1−x (Al 2 O 3 ) x samples have been prepared using solid state reac... more Series of (YBa 2 Cu 3 O 7−δ ) 1−x (Al 2 O 3 ) x samples have been prepared using solid state reaction method. Various amount of nano-sized Al 2 O 3 particles (∼50 nm) were added with (x = 0, 0.005, 0.01, 0.02, and 0.05). The microstructure and the morphology of the polycrystalline samples have been characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). The magnetotransport properties of these samples were investigated using resistance-temperature (R-T ) and current-voltage (I -V ) characteristics. All samples showed an orthorhombic structure with a tendency to transformation to tetragonal phase at higher levels of nanoparticles addition. The morphology of the surface of pure samples reveals a considerable number of weak-links, randomly oriented and clean grain boundaries. While in samples with nano inclusions, grain boundaries were filled with nanosized particle and have less number of weak-links. Significant enhancement of the superconducting critical current density J c in applied magnetic field was observed due to nano Al 2 O 3 inclusions. However, further increase in the value of x decreases the transition temperature T c and the critical current density J c . These results were interpreted in terms of the flux pinning mechanisms in granular superconducting networks which leads to a better basic understanding of the performance of YBCO system in high applied magnetic fields.
Magnetization measurements on zero field cooled (ZFC) and field cooled (FC) samples as a function... more Magnetization measurements on zero field cooled (ZFC) and field cooled (FC) samples as a function of temperature where made on Fe Mn Al alloys with 0#x#0.10. Our data show the existence of two regimes of the spin glass temperature T when increasing 0.702x x 0.30 f the concentration x of the Mn atoms. We found that T decreases slowly with increasing x up to x50.06 and then shows a rapid linear f decrease above this concentration. The existence of two regimes of T behavior with x may be attributed to the disappearance of f ferromagnetic clusters which exist for low values of x (x,0.06). Compared to the Mn-free alloy, the relative changes in T are bigger and f exceed 40% at x50.10. The second regime (x.0.06) is associated with more influence of x on T .
We report the structural and magnetic properties of GdFe Ti alloys, where x50, 0.05, 0.10, 0.15, ... more We report the structural and magnetic properties of GdFe Ti alloys, where x50, 0.05, 0.10, 0.15, 0.20, 0.30. X-ray diffraction shows 22x
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