Evolution of structural, magnetic and magnetocaloric properties in Sn-doped manganites La0.57Nd0.1Sr0.33Mn1−xSnxO3 (x = 0.05–0.3)

• Published in: Applied physics. A, Materials science & processing Materials science & processing, 2014-09, Vol.116 (3), p.1181-1191
• Main Authors: Tka, E., Cherif, K., Dhahri, J.
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Condensed Matter Physics; Machines; Manufacturing; Nanotechnology; Optical and Electronic Materials; Physics; Physics and Astronomy; Processes; Surfaces and Interfaces; Thin Films
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-013-8202-5

Structural and magnetic properties of manganites series La 0.57 Nd 0.1 Sr 0.33 Mn 1− x Sn x O 3 with (0.05 ≤  x  ≤ 0.30) have been investigated, and the critical exponents and magnetocaloric effect are studied around the room temperature, to shed light on Sn substitution influence. A solid-state reaction method was used in the preparation. A structural study using Rietveld refinement of XRD patterns indicates rhombohedral structure with R 3 ¯ c space group for (0.05 ≤  x  ≤ 0.20) and shows the existence of a secondary phase attributed to the neodymium tin oxide (Nd 2 Sn 2 O 7 ) pyrochlore for x  = 0.3. The variation of the magnetization (M) vs. temperature ( T ), under an applied magnetic field of 0.05 T, reveals a ferromagnetic–paramagnetic transition at the Curie temperature T C . In addition, it was discovered that increasing the tin content leads to a reduction in magnetization and a lowering of T C from 282 K ( x  = 0.05) to 158 K ( x  = 0.20) with increasing Sn substitution. The samples exhibit the characteristics of spin/cluster-glass state which is evident from (zero-field-cooled and field-cooled) magnetization vs. temperature curves. Indeed, the thermal evolution of magnetization in the ferromagnetic phase at low temperature varies as T 3/2 , in accordance with Bloch’s law. The spin-stiffness constant D obtained from the Bloch constant was determined. A large magnetocaloric effect has been observed in both samples ( x  = 0.05 and x  = 0.10): the maximum entropy change, Δ S M peak , reaches the highest value of 3.22 J/kg K under a magnetic field change of 5 T with a RCP value of 56 J/kg for x  = 0.10 composition. This opens an interesting opportunity to this compound to compete with materials which work as magnetic refrigerants near room temperature. Besides, we show that the samples follow the conventional behavior of a second-order ferromagnetic transition. This was possible by investigating the critical behavior at the transition region by adopting the modified Arrott plot method. The values of the critical exponents ( β , γ , δ and n ) are determined and they are between those predicted by the three-dimensional Heisenberg model.