Yazar "Meriche, Faiza" seçeneğine göre listele

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    Investigation of hole-doping effect on structural, magnetic properties and magnetoresistance via Gd-site substitution by Pb in the layered manganite La0.1Gd0.2-xPbxCa1.2Sr0.6Mn2O7 (0 <= x <= 0.2)
    (Springer, 2023) Belguet, Radjia; Mahamdioua, Nabil; Meriche, Faiza; Alonso, Jose A.; Martinez, Jose L.; Altıntaş, Sevgi Polat; Terzioğlu, Cabir
    In this work, the hole-doping double-layered manganites with formula La1:0Gd(0.2-x)PbxCa1.2Sr0.6Mn2O7 (x = 0, 0.1, and 0.2) are prepared by the solidstate reaction route and experimentally characterized. The samples' crystallization into a tetragonal structure with an I4/mmm space group was confirmed by Rietveld refinement results of the XRD diffraction patterns using the FullProf software. The results were thoroughly studied after it was discovered that the cell parameters were decreasing. The structure was granular and porous, with grains that resembled spheres, according to micrographs obtained using a scanning electron microscope (SEM). Fourier-transform infrared (FTIR) analysis shows that our samples' characteristic vibrational bands are present. The entire temperature range of 0 to 300 K was used to evaluate electrical resistivity both in the absence and in the presence of an applied magnetic field. The increase in bandwidth, which is determined from the Rietveld refinement results, is found to explain why the rho(T) lowers with increasing Pb concentrations for a given temperature. The calculated magnetoresistance (MR%) for sample with x = 0.1 fell to 24.62% at 8 K for x = 0.2 from a maximum value of 30.01% at 5 K under 1 T of applied magnetic field. These values give our samples the opportunity to be good candidates in temperature and magnetic sensors in the cryogenic domains at low magnetic field. Residual resistivity, weak localization, electronelectron, and/or electron-phonon combinations fit the resistivity curves well in the low temperature region. The resistivity curves' fitting revealed that the adiabatic tiny polaron hopping model and Mott's 3D variable range hopping mechanism (3D-VRH) are both effective at controlling electrical conduction above T-MI and below Debye temperature, respectively. Based on Mott's 3D-VRH model, the density of states near the Fermi level (DOS), mean hopping distance Rh, and mean hopping energy E-h of the charge carriers have been carried out and discussed. On the basis of measurements of magnetization, inverse susceptibility, and loop hysteresis, the samples' magnetic properties are thoroughly described and discussed. The samples show a magnetic phase change from the ferromagnetic to the paramagnetic phase at Curie temperature T-C. Griffith phase temperature was determined to be above T-C based on the inverse of susceptibility's temperature dependency.
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    Non-adiabatic small-polaron and 3D-Mott's variable range conductions above 100 K in Pb-substituted double-layered manganites LaSm0.4Ca1.6-xPbxMn2O7
    (Pergamon-Elsevier Science Ltd, 2022) Denbri, Fatih; Mahamdioua, Nabil; Meriche, Faiza; Altıntaş, Sevgi Polat; Terzioğlu, Cabir
    In this study, the role of Pb substitution on the microstructural and magneto-transport properties of the double layered manganites LaSm0.4Ca1.6-xPbxMn2O7 (x = 0, 0.1 and 0.2), prepared by the solid-state reaction method, was investigated. On the samples, X-Ray Diffraction, Scanning Electron Microscopy and resistivity as a function of temperature measurements were performed. XRD measurements revealed that the samples crystallized in a tetragonal phase with an I4/mmm space group and that the lattice parameters increased with increasing Pb content. SEM measurements indicated the granular character and the average grain sizes ranged between 0.5 and 4 mu m for all the samples. The temperature dependence of resistivity of all the samples shows insulating-like behavior for the studied range of temperature (T > 100 K). The maximum magnetoresistance (MR%) value was found to be 31.95% at 100 K for the sample with x = 0, while it was 11% and 8% for the samples with x = 0.1 and 0.2, respectively. The resistivity curves are found to be well described by the Adiabatic Small Polaron Model in the range and Mott's 3D Variable Range Hopping model in the range. The density of states near the Fermi level (DOS), mean hopping distance, and mean hopping energy values were computed in the range, and the role of Pb substitution on these parameters was discussed as well.
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    Optical and magnetic properties of the La0.7RE0.1Ca0.2CrO3 (RE = Nd, Sm and Eu) orthochromite for optoelectronic and magnetic applications
    (Springer, 2023) Bouasla, Fatima Zohra; Mahamdioua, Nabil; Alonso, Jose A.; Martinez, Jose L.; Meriche, Faiza; Terzioğlu, Cabir; Altıntaş, Sevgi Polat
    The orthochromites La0.7RE0.1Ca0.2CrO3 (RE = Nd,Sm, and Eu) were prepared by solid-state reaction and the structural, microstructural, optical, and magnetic properties were investigated. The XRD revealed an orthorhombic perovskite structure. The UV–visible revealed the bandgap energy values: 2.81, 2.98, and 3.12 eV for Nd, Sm, and Eu doped samples, respectively. It is explained by the creation of the localized state. The refractive index, Urbach energy, and optical conductivity were investigated. The magnetization investigation revealed that the Ne´el temperature decreases with decreasing substituting ionic radius. Below TN, all samples exhibit weak ferromagnetic behavior due to the t-e hybridization caused by intrinsic distortions. The Nd and Sm doped samples show spin reorientation due to the exchange interaction between the Sm3?/Nd3? and Cr3?. The negative magnetization of the Nd-doped sample indicates its possible use as a volatile memory device. Regarding the Eg values, our samples could be suit able candidates for optoelectronic devices
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    Structural, electrical, magnetic and magnetotransport properties of La0.7Ca0.18Ba0.12Mn0.95Sn0.05O3 manganite prepared with different quenching processes
    (Springer Heidelberg, 2023) Belal, Ibtihal; Meriche, Faiza; Mahamdioua, Nabil; Denbri, Fatih; Altıntaş, Sevgi Polat; Terzioğlu, Cabir
    Structural, microstructural, magnetic, electrical and magneto-transport properties of La0.7Ca0.18Ba0.12Mn0.95Sn0.05O3 manganite powders, prepared by the solid state method, were investigated. Two quenching processes were performed on the samples: quenching in air and quenching to 77 K in liquid nitrogen. X-ray diffraction patterns refinement revealed that the samples crystallized in the orthorhombic structure. The scanning electron microscopy micrographs presented granular characters. The magnetization vs temperature plot showed a paramagnetic-ferromagnetic transition. The inverse susceptibility chi(-1)(T) deviation from the Curie-Weiss law revealed the existence of the phase above T-C in the nitrogen-quenched sample. The hysteresis cycles reveal that the samples are ferromagnetic at 1.8 K and paramagnetic at 300 K. The resistivity curves exhibit a ferromagnetic-metallic to paramagnetic-insulating transition. The magnetoresistance increased slightly in the sample quenched to 77 K in N-2.