Magnetic entropy change in LaFe13−xSix intermetallic compounds

Abstract

LaFe 13−x Si x compounds with x=2.4, 2.6, and 2.8 have been carefully prepared and characterized. X-ray powder diffraction patterns confirm that the samples crystallize in a single NaZn13-type phase. Magnetic measurements were carried out in a SQUID magnetometer. The Curie temperature Tc of LaFe13−xSix samples decreases nearly 50 K with x increasing from 2.4 to 2.8. Around Tc the samples exhibit a typical second-order phase transition; and no trace of first-order itinerant electron metamagnetic transition is found. So it is reliable to characterize the magnetic entropy change around Tc using magnetic measurement. The maximum values of the magnetic entropy change of LaFe13−xSix samples are found to be, at their Curie temperatures, 5.85, 5.9, and 3.7 J/kg.K for x=2.4, 2.6, and 2.8 under a field change of 5 T (0–5 T). For the quite large magnetic entropy change over a wide temperature range, LaFe13−xSix compounds appear, therefore, to be a potential material candidate for magnetic cooling.