Structural, magnetic and magnetocaloric properties in La0.7-xDyxSr0.3MnO3 manganites (x = 0.00, 0.01 and 0.03)

• Published in: Journal of alloys and compounds 2017-03, Vol.696, p.760-767
• Main Authors: Sfifir, I., Ezaami, A., Cheikhrouhou-Koubaa, W., Cheikhrouhou, A.
• Format: Article
• Language: English
• Subjects: Chemical compounds; Curie temperature; Diffraction patterns; Elongation; Ferromagnetism; Lanthanum compounds; Magnetic fields; Magnetic measurement; Magnetic properties; Magnetization; Magnetocaloric effect; Manganese oxides; Manganites; Phase transitions; Sol-gel processes; Unit cell; X-ray diffraction
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2016.11.286

Structural, magnetic and magnetocaloric properties of La0.7-xDyxSr0.3MnO3 (x = 0.00, 0.01 and 0.03) powder samples have been investigated by X-ray diffraction (XRD) and magnetic measurements. Our samples have been synthesized using the sol-gel method. Rietveld refinements of the X-ray diffraction patterns show that all our samples are single phase and we have noticed that the Dy doping causes a structural transition from a rhombohedral structure with R-3c space group to an orthorhombic one with Pnma space group and a decrease in the unit cell volume. In fact, the substitution of La3+ by Dy3 induces a distortion of the unit cell, an elongation along the a- and c-axes and therefore a decrease of the unit cell volume. Magnetization measurements versus temperature in a magnetic applied field of 0.05 T show that all our samples exhibit a paramagnetic-ferromagnetic transition with decreasing temperature. The Curie temperature TC is found to be 319 K, 315 K and 264 K for x = 0.00, 0.01 and 0.03, respectively. Arrott plots show that all our samples exhibit a second order magnetic phase transition. From the measured magnetization data of La0.7-xDyxSr0.3MnO3 (x = 0.00, 0.01 and 0.03) samples as a function of the magnetic applied field, the associated magnetic entropy change |−ΔSM| and the relative cooling power RCP have been determined. In the vicinity of TC, |−ΔSM| reached, in a magnetic applied field of 5 T, a maximum value of 1.63 J/KgK, 1.21 J/kg K and 1.05 J/kg K for x = 0.00, 0.01 and 0.03, respectively. •Our powder specimens were synthesized using the sol-gel method.•Dy doping causes a structural transition form a rhombohedral to an orthorhombic structure.•The Curie temperature TC is found to be 319, 315 and 264 K for x = 0.00, 0.01 and 0.03 samples respectively.