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725 results on '"Lassri, H."'

42. Magnetic phase transition and magnetocaloric effect in amorphous Gd52Fe28B20 alloy.

Author

El Ouahbi, B., Abouricha, M., El Ouahbi, S., Lassri, M., Sajieddine, M., Ounza, Y., and Lassri, H.

Subjects
MAGNETIC transitions, MAGNETOCALORIC effects, AMORPHOUS alloys, LANDAU theory, MELT spinning, MAGNETIC entropy
Abstract

Magnetic phase transition and magnetocaloric effect in the amorphous Gd52Fe28B20 alloy are exhaustively explored. The melt spinning technique was employed to produce the amorphous alloy. Considering the Landau theory and Banerjee criterion, the nature of the magnetic phase transition (MPT) follows a second order MPT at the Curie temperature (TC) from ferromagnetic to paramagnetic states. The Maxwell thermodynamic relation was used to calculate the maximum isothermal entropy change (− ∆SM). This alloy exhibits wide peaks in entropy versus temperature curves, which is advantageous for enhancing the relative cooling power (RCP). The RCP of Gd52Fe28B20 was found to be ~ 190 J kg−1 (at TC = 260 K, µ0H = 2 T), the value similar to that obtained in pure Gd (at TC = 293 K, µ0H = 2 T). Additionally, we provide a phenomenological model related to the theoretical assessment of the magnetocaloric effect. The dependence of theoretical parameters on temperature and magnetic field was established through rigorous analysis. The accuracy of these theoretical predictions was assessed by comparing them to experimental results. Consequently, this alloy is appropriate for use near the ordering temperature of 260 K, which bodes well for the development of novel magnetic refrigerants for active cooling applications. [ABSTRACT FROM AUTHOR]

Published
2024
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43. Structural, linear and nonlinear optical properties of Pb(Mg1/3Nb2/3)O3-PbTiO3 nanoparticles.

Author

Laghfiri, C., Rhrissi, I., Arba, Y., Bouhmouche, A., Lakhlifi, H., Mehdaoui, B., Mliki, N., Saeedi, A. M., Lassri, H., and Moubah, R.

Abstract

Pb(Mg1/3Nb2/3)O3-PbTiO3 nanoparticles were synthesized by solid-state route. The crystal structure and optical properties were characterized by X-ray diffraction and UV–visible spectroscopy. X-ray diffraction confirmed the perovskite structure and the mean size of the crystallites was determined by employing the Williamson–Hall (W–H) model. From the UV–Visible measurements, several fundamental optical properties such as transmittance, absorbance, refractive index, band gap (Eg), Urbach energy, optical conductivity, dielectric function, and absorption coefficient were determined. The band gap energy was found to be around 3.05 eV with a high transmittance value for high wavelength. Further, the optical data were utilized to investigate the linear susceptibility, third-order nonlinear optical susceptibility, and nonlinear refractive index of the sample. It is found that the values of χ(1), χ(3) and n2 were equal to 0.053 esu, 1.33 × 10−15 esu, and 3.88 × 10−14 esu, respectively. [ABSTRACT FROM AUTHOR]

Published
2024
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