Magnetic entropy change in Fe-based compound LaFe10.6Si2.4

Abstract

A large magnetic entropy change has been observed in an intermetallic compound LaFe10.6Si2.4. The maximum −ΔSM≈3.2 J/kg K was found at its Curie temperature, ∼242 K, upon a 2 T magnetic field change. Although the entropy change is slightly smaller than that of pure Gd metal, such Fe-rich compounds still appear to be very attractive candidates since (a) the raw materials are much cheaper than pure Gd metal; (b) the Curie temperature can be easily shifted by tuning the composition; (c) the materials are much more chemically stable than pure Gd metal.

Phase formation and structure in rapidly quenched alloys

“…LaFe 13−x Si x pseudobinary compounds with the NaZn 13 structure (1.5 ≤ x ≤ 2.5) were firstly reported by Palstra et al [1] in 1983 and are enjoying renewed interest [2][3][4][5][6][7] in the magnetic materials community due to the observation of a large magnetocaloric effect (MCE) in LaFe 11.4 Si 1.6 [2]. The actual magnetic refrigerant typical works at a temperature range and generally is a composite of several magnetocaloric materials with different Curie temperatures (T C ), because the MCE peak occurs near T C .…”

“…Subsequent energy and time-consuming annealing treatment is therefore required to gain a single phase with the 1:13 structure. In all reported works on La(Fe, Co, Si) 13 [1][2][3][4][5][6][7][8][9], samples were prepared by induction-or arc-melting followed by a long time (several weeks to 2 months) annealing at about 1073-1273 K. An effective preparation method is important from an application viewpoints. Improved production routes can be developed provided the primary solidification of pro-peritectic ␥-Fe is suppressed and the 1:13 phase is directly solidified from the near stoichiometric melt.…”

The effect of temperature span of the first-order transition processes on magnetic entropy change in NiMnGa alloys

“…Many material systems undergoing a firstorder magnetic transition have shown a giant MCE. The typical representatives of them are MnFeP 1−x As x compounds [2], MnAs 1−x Sb x [3], Gd 5 (Si x Ge 1−x ) 4 [4,5] alloys, La(Fe x Si 1−x ) 13 [6,7] alloys and so on. The Heusler-type alloy NiMnGa exhibits two types of phase transitions, one is the structural transition from ferromagnetic austenite to ferromagnetic martensite, and the other one is the magnetic transition from ferromagnetic austenite to paramagnetic austenite.…”

Structural and magnetic properties of magnetocaloric LaFe13–xSix compounds synthesized by high energy ball-milling

“…Many studies have been carried out in order to increase the Curie temperature of these materials by substituting La and Fe respectively by another rare-earth or transition metal such as Co or by the insertion of interstitial atoms like hydrogen or carbon [5]. Several synthesis methods have been explored such as arc-melting or induction-melting for which a prolonged heat treatment of about one month is needed to obtain an almost single phase NaZn 13 structure in the samples [7,8]. Recently several studies on the synthesis of LaFe 13ex Si x compounds by melt-spinning have been reported [9e12].…”