Study on magnetocaloric effect and phase transition in La0.7(La–Ce)0.3FexAl11.5−xSi1.5 alloys

• Published in: Intermetallics 2021-09, Vol.136, p.1, Article 107269
• Main Authors: Wang, G.F., Ren, W., Yang, B.Y.
• Format: Article
• Language: English
• Subjects: Alloys; Curie temperature; Magnetic materials; Magnetic properties; Magnetism; Magnetocaloric effect; Phase transition; Phase transitions; Refrigeration
• ISSN: 0966-9795; 1879-0216
• DOI: 10.1016/j.intermet.2021.107269

Magnetocaloric materials with high performance are crucial to the achievement of magnetic refrigeration which is a promising cooling technology to replace traditional gaseous compression refrigeration. In this work, the magnetocaloric effect and phase transition of La0.7(La–Ce)0.3FexAl11.5−xSi1.5 alloys have been investigated. The structural and magnetic properties were characterized by means of X-ray diffraction and magnetization measurements. Belov-Arrott plots and the exponent n from field dependence of isothermal entropy change were applied to determine the nature of the phase transition. The XRD patterns indicate that the alloys crystallize mainly in NaZn13-type phase with small amounts of α-Fe and LaFeSi as secondary phases. With an increase of x from 11.0 to 11.4, the Curie temperature decreases from 211.2 K to 185.4 K while the magnetocaloric effect increases from 4.9 J kg−1 ⋅K−1 to 23 J kg−1 ⋅K−1 for a field change of 2 T. The alloys show refrigeration capacity between 111 J ⋅kg−1 and 152 J ⋅kg−1 for a magnetic field of 2 T. Analyses of the Belov-Arrott plot and the exponent of n reveal that the first-order itinerant-electron metamagnetic phase transition in the alloys is weakened by decreasing x, and the alloys with x = 11.2, 11.3 and 11.4 undergo a second-order phase transition. •La0.7(La–Ce)0.3FexAl11.5-xSi1.5 alloys were prepared.•The Curie temperature of the alloys increases with decreasing x.•The magnetocaloric effect of the alloys increases with increasing x.•The nature of the phase transition was analyzed.•The alloys exhibit large refrigeration capacity.