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Nanomatériaux multifontionnels à base de terre rare et de métalde transition : propriétés structurales, magnétiques etmagnétocaloriques

Abstract : Multifunctional nanomaterials based on rare-earth (R) and transition metal (T) present a major interest in scientific research. We are interrested in the Pr5Co19 alloy. This system crystallizes in the rhombohedral Ce5Co19-type structure with space group R-3m. The Curie temperature Tc is about 690 K. We determined the value of the magnetization at saturation MS = 83 Am2 / kg using the approach law to saturation. A uniaxial anisotropy with a coercive field equal to 1.5 T at room temperature were obtained.Moreover, we have observed that the insertion of a light element such as carbon or hydrogen, allows to increase the Curie temperature of the system. The Pr5Co19Hx hydrides present a reversible cycle of absorption/desorption, with a hydrogen absorption capacity equal to 12H / f.u, or 0.5H / M in total.We are also interested in the study of the magnetocaloric effect of the intermetallics Pr-Co type. We have shown that Pr5Co19 compound has a giant magnetocaloric effect, of about 5.2 J / kg.K at low field.The intermetallic nanomaterials Pr5Co19 could be used as a multifunctional compound. These results indicate that it is an attractive alloy due to its structural, magnetic and magnetocaloric properties. It could be good candidates for permanent magnets, but also for magnetic refrigeration at high temperature and for hydrogen storage
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Wassim Bouzidi. Nanomatériaux multifontionnels à base de terre rare et de métalde transition : propriétés structurales, magnétiques etmagnétocaloriques. Matériaux. Université Paris-Est; Université Paris-Est (2015-..); Université de Tunis El Manar, 2018. Français. ⟨NNT : 2018PESC1084⟩. ⟨tel-02918092⟩

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