Magnetic entropy table-like shape and enhancement of refrigerant capacity in La1.4Ca1.6 Mn2O7 –La1.3Eu0.1Ca1.6Mn2O7 composite - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue RSC Advances Année : 2019

Magnetic entropy table-like shape and enhancement of refrigerant capacity in La1.4Ca1.6 Mn2O7 –La1.3Eu0.1Ca1.6Mn2O7 composite

Résumé

In this work, we have investigated the structural, magnetic and magnetocaloric properties of La1.4Ca1.6Mn2O7 (A) and La1.3Eu0.1Ca1.6Mn2O7 (B) oxides. These compounds are synthesized by a solid-state reaction route and indexed with respect to Sr3Ti2O7-type perovskite with the I4/mmm space group. The substitution of La by 10% Eu enhances the value of magnetization and reduces the Curie temperature (TC). It is also shown that these compounds undergo a first-order ferromagnetic–paramagnetic phase transition around their respective TC. The investigated samples show large magnetic entropy change (ΔSM) produced by the sharp change of magnetization at their Curie temperatures. An asymmetric broadening of the maximum of ΔSM with increasing field is observed in both samples. This behaviour is due to the presence of metamagnetic transition. The ΔSM(T) is calculated for Ax/B1−x composites with 0 ≤ x ≤ 1. The optimum ΔSM(T) of the composite with x = 0.48 approaches a nearly constant value showing a table-like behaviour under 5 T. To test these calculations experimentally, the composite with nominal composition A0.48/B0.52 is prepared by mixing both individual samples A and B. Magnetic measurements show that the composite exhibits two successive magnetic transitions and possesses a large MCE characterized by two ΔSM(T) peaks. A table-like magnetocaloric effect is observed and the result is found to be in good agreement with the calculations. The obtained ΔSM(T) is ≈4.07 J kg−1 K−1 in a field change of 0–5 T in a wide temperature span over ΔTFWHM ∼ 68.17 K, resulting in a large refrigerant capacity value of ≈232.85 J kg−1. The MCE in the A0.48/B0.52 has demonstrated that the use of composite increases the efficiency of magnetic cooling with μ0H = 5 T by 23.16%. The large ΔTFWHM and RC values together with the table-like (−ΔSM)max feature suggest that the A0.48/B0.52 composite can meet the requirements of several magnetic cooling composites based on the Ericsson-cycle. In addition, we show that the magnetic field dependence of MCE enables a clear analysis of the order of phase transition. The exponent N presents a maximum of N > 2 for A, B and A0.48/B0.52 samples confirming a first-order paramagnetic–ferromagnetic transition according to the quantitative criterion. The negative slope observed in the Arrott plots of the three compounds corroborates this criterion.
Fichier principal
Vignette du fichier
c9ra00984a.pdf (5.38 Mo) Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte

Dates et versions

hal-02413254 , version 1 (24-08-2023)

Identifiants

Citer

R. M'Nassri, Muaffaq Nofal, Patricia de Rango, N. Chniba-Boudjada. Magnetic entropy table-like shape and enhancement of refrigerant capacity in La1.4Ca1.6 Mn2O7 –La1.3Eu0.1Ca1.6Mn2O7 composite. RSC Advances, 2019, 9 (26), pp.14916-14927. ⟨10.1039/c9ra00984a⟩. ⟨hal-02413254⟩

Collections

UGA CNRS NEEL
23 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More