fikry_99

أ.د. احمد محمد احمد على( احمد فكرى)

استاذ - عميد كلية العلوم

كلية العلوم

العنوان: ش 116 متفرع من ش الهدرجة سوهاج

5

إعجاب
2019 | الكلمات المفتاحية Magnetocaloric effect,
Crossover effect of magnetotransport and magnetocaloric effect in (La0.7Ba0.3MnO3)1-x/(Al2O3)x composites
Magnetotransport properties and magnetocaloric effect of (La0.7Ba0.3MnO3)1-x/(Al2O3)x composites have been investigated through their theoretical and experimental studies. The Al2O3 addition increases the resistivity, showing up a crossover from 3D Mott to the soft gap variable range hopping (VRH). The relative cooling power of LBMO matrix (~98.77 Jkg−1, H = 2 T) is approximately 65 percentage of that of pure Gd ... إقراء المزيد

2019 | الكلمات المفتاحية
Impact of aluminum on the Seebeck coefficient and magnetic properties of La0.7Ba0.3MnO3 manganites
The effect of aluminum on (La0.7Ba0.3MnO3)1-x/(Al2O3)x composites is investigated based on their crystal structure, thermoelectric power and magnetic properties. The X-ray diffraction process reveals that the composite still exhibits a rhombohedral perovskite structure (R3¯C) of all composites. The thermoelectric power data satisfies the Magnon and Phonon-drag models in the low-temperature range, and the smaller Polaron conduction mechanism in the high-temperature ... إقراء المزيد

2018 | الكلمات المفتاحية
Electric, thermoelectric and magnetic characterization ofγ-Fe2O3and Co3O4 nanoparticles synthesized by facile thermal decomposition of metal-Schiff base complexes, E.M.M. Ibrahim, Laila H. Abdel-Rahman, Ahmed M. Abu-Dief, A. Elshafaie, Samar Kamel Hamdan, A.M. Ahmed,
The physical properties, such as electric and optical properties, of metal-Schiff base complexes have been widely investigated. However, their thermoelectric (TE) properties remain unreported. This work presents Cu(II)-Schiff base complexes as promising materials for TE power generation. Therefore, three Cu(II)-Schiff base complexes (namely, [Cu(C32H22N4O2)].3 2H2O, [Cu(C23H17N4O7Br)], and [Cu(C27H22N4O8)].H2O) have been synthesized in nanosized scale. The electric and TE properties have ... إقراء المزيد

2018 | الكلمات المفتاحية
Effect of NiO impurity on the magneto-transport properties of the La0.7Ba0.3MnO3 granular manganite
Magnetoresistive, magnetic and thermoelectric properties of the La0.7Ba0.3MnO3/xNiO system are studied. The x-ray diffraction shows the coexistence of the NiO and the La0.7Ba0.3MnO3 phases in doped composites, revealing their interaction lack. This suggests the precipitation of the NiO at grain boundaries and on the La0.7Ba0.3MnO3 surface, interrupting the conduction between grains. Hindering the direct contact between the La0.7Ba0.3MnO3 grains increases ... إقراء المزيد

2017 | الكلمات المفتاحية
Synthesis, characterization and low field magnetotransport of Nd0.6Sr0.4MnO3/ CrO3 composite
(Nd0.6Sr0.4MnO3)1-x/(CrO3)x with x = 0.0–0.030 step 0.005 weight% composites have been prepared by the solid state reaction process. The X-ray and scanning electron microscopic manifest that all composites are a single orthorhombic phase and there are no CrO3 grains separated from NdSrMnO matrix. The electrical measurements have revealed an increase of resistivity and a decrease of metal semiconductor transition with ... إقراء المزيد

2017 | الكلمات المفتاحية
Magnetic, magnetocaloric and thermoelectric properties of nickel doped manganites,
In this study, we investigate structural, magnetic, magnetocaloric and thermoelectric properties of La0.7Sr0.3Mn1-xNixO3 compounds with 0.025 x 0.125. X-ray diffraction analysis shows the structure transformation from the R-3c rhombohedral to the Pbnm orthorhombic structure with Ni2þ doping at x 0.075 composites. The dc thermal magnetization measurements reveal the monotonic decrease in both Curie temperature and magnetization values with Ni2þ addition. ... إقراء المزيد

2017 | الكلمات المفتاحية
Electrical, thermoelectrical and magnetic properties of approximately 20-nm Ni-Co-O nanoparticles and investigation of their conduction Phenomena ,
Understanding the properties of semiconductor nanostructures is important for developing their practical applications in the nanodevices. Although the electrical properties of spinel oxides containing Ni and Co have been studied extensively over the last decades, there is still a significant disagreement on their electrical conduction mechanisms and the distribution of the various charge states of Co and Ni in the ... إقراء المزيد

2016 | الكلمات المفتاحية
Magnetoresistive and magnetocaloric response of manganite/insulator  system,   ,
In this work, we have studied structural, electro-magnetic and magnetocaloric properties of La0.7Ba0.3MnO3/ xTiO2 manganite/insulator system with 0 x 0.08. X-ray diffraction (XRD) shows the coexistence of TiO2 and La0.7Ba0.3MnO3 phases in doped composites through their characteristic peaks. This reveals their interaction lack preserving the R-3c rhombohedral structure for all composites. Due to interaction lack, TiO2 is suggested to segregate ... إقراء المزيد

2016 | الكلمات المفتاحية
Annealing temperature effect on magnetic and magnetocaloric properties of manganites
In this work, we investigate the effect of annealing process at different temperatures (600 and 800 C) on structural, magnetic and magnetocaloric properties of La0.7Ba0.3MnO3/xTiO2 system with x ¼ 0.04 and 0.06. Crystal structure analysis shows the R-3c rhombohedral symmetry for composites in both annealing temperatures indicating structure stability. Magnetization and coercive field of doped composites increase with increasing annealing ... إقراء المزيد

2016 | الكلمات المفتاحية
Magnetocaloric-transport properties correlation in doped manganites
Magnetocaloric-transport properties correlation in doped manganites إقراء المزيد