We report on the structural,magnetic,and magnetocaloric properties of EuRhO_(3) powders.The oxidation states of Eu and Rh ions were studied using X-ray photoelectron spectroscopy(XPS).It is found that the Eu ions are ...We report on the structural,magnetic,and magnetocaloric properties of EuRhO_(3) powders.The oxidation states of Eu and Rh ions were studied using X-ray photoelectron spectroscopy(XPS).It is found that the Eu ions are mainly in the divalent oxidation state while the Rh ions have+4 state.EuRhO_(3) powders are found to be antiferromagnetic with a second order magnetic transition at Neel temperature(T_(N)=2.9 K).Analysis of the magnetic susceptibility versus temperature data in terms of the Curie=Weiss law:(χ=C/(T-θ_(W))) for T>T_(N),yields θ_(W)=-3.1 K and effective magne tic moment μ_(ff)^(exp),which is close to the theoretical value μ_(eff)^(theo).The magnetic entropy change(-Δ_(SM)),was determined by em ploying the thermodynam ic Maxwell's relation.At μ_0H=5 T and near T_(N),ΔS_(M)^(Max) and relative cooling power(RCP) exhibit large values of 33.7 J/(kg·K) and 238 J/kg,respectively.The large magnitude of-Δ_(SM) and RCP show that the EuRhO_(3) compound could be a potential candidate to be used in cryogenic magnetic refrigeration.展开更多
The main objective of this investigation is to valorize a Moroccan crop residue(Sabra fibers,Agave Americana L.)and to compare with Alfa fibers(,Stipa tenacissima L.)as reinforcement in an elastomeric matrix in term o...The main objective of this investigation is to valorize a Moroccan crop residue(Sabra fibers,Agave Americana L.)and to compare with Alfa fibers(,Stipa tenacissima L.)as reinforcement in an elastomeric matrix in term of the relaxation properties,mechanical and rheological properties.The preparation and properties of these two natural fibers embedded in Styrene-Butadiene Rubber(SBR)are presented with and without the addition of Styrene-Ethylene-Butadiene-Styrene grafted with Maleic Anhydride(SEBS-g-MA)as a coupling agent.Five different series(SBR,SBR/Alfa,SBR/Alfa/SEBS,SBR/Sabra and SBR/Sabra/SEBS)were compounded by extrusion and compression molding.As a result,the addition of the coupling agent in the elastomeric matrix improves the relaxation properties,mechanical and rheological properties.Moreover,Sabra fibers show the good results compared to Alfa fibers.Finally,the Zener model was used to determine the rheological time response of the composites.A good agreement between the experimental data and the model was observed(R^2=0.99).展开更多
文摘We report on the structural,magnetic,and magnetocaloric properties of EuRhO_(3) powders.The oxidation states of Eu and Rh ions were studied using X-ray photoelectron spectroscopy(XPS).It is found that the Eu ions are mainly in the divalent oxidation state while the Rh ions have+4 state.EuRhO_(3) powders are found to be antiferromagnetic with a second order magnetic transition at Neel temperature(T_(N)=2.9 K).Analysis of the magnetic susceptibility versus temperature data in terms of the Curie=Weiss law:(χ=C/(T-θ_(W))) for T>T_(N),yields θ_(W)=-3.1 K and effective magne tic moment μ_(ff)^(exp),which is close to the theoretical value μ_(eff)^(theo).The magnetic entropy change(-Δ_(SM)),was determined by em ploying the thermodynam ic Maxwell's relation.At μ_0H=5 T and near T_(N),ΔS_(M)^(Max) and relative cooling power(RCP) exhibit large values of 33.7 J/(kg·K) and 238 J/kg,respectively.The large magnitude of-Δ_(SM) and RCP show that the EuRhO_(3) compound could be a potential candidate to be used in cryogenic magnetic refrigeration.
文摘The main objective of this investigation is to valorize a Moroccan crop residue(Sabra fibers,Agave Americana L.)and to compare with Alfa fibers(,Stipa tenacissima L.)as reinforcement in an elastomeric matrix in term of the relaxation properties,mechanical and rheological properties.The preparation and properties of these two natural fibers embedded in Styrene-Butadiene Rubber(SBR)are presented with and without the addition of Styrene-Ethylene-Butadiene-Styrene grafted with Maleic Anhydride(SEBS-g-MA)as a coupling agent.Five different series(SBR,SBR/Alfa,SBR/Alfa/SEBS,SBR/Sabra and SBR/Sabra/SEBS)were compounded by extrusion and compression molding.As a result,the addition of the coupling agent in the elastomeric matrix improves the relaxation properties,mechanical and rheological properties.Moreover,Sabra fibers show the good results compared to Alfa fibers.Finally,the Zener model was used to determine the rheological time response of the composites.A good agreement between the experimental data and the model was observed(R^2=0.99).
