Microstructure and magnetocaloric effect of LaFe11Co0.8Si1.2 strip-cast flakes

Magnetic refrigeration based on the magnetocaloric effect (MCE) is an environmentally friendly and energy efficient solid state cooling technology compared with conventional vapor compression approach In recent years, the interest in large MCE materials including Gd
₅
Si
_4-x
Ge
_x
, LaFe
_13-x
Si
_x
, MnFeP(As, Ge), Ni-Mn-based Heusler alloys, and rare-earth manganites has grown considerably due to their potential application as refrigerants in magnetic cooling at room temperature [1]. Among these materials, NaZn
₁₃
-type La(Fe, Si)
₁₃
-based compounds have attracted much attention as one of the most promising candidates for a magnetic refrigerant because of their high magneto-caloric performances, low materials cost, non-toxic characters and relatively low hysteresis From an application point of view, La(Fe
_x
Si
_1-x
)
₁₃
H
_y
and La(Fe, Co)
_13-x
Si
_x
compounds are recently considered as desirable materials for room temperature magnetic refrigeration However, the formation of the NaZn
₁₃
-type structure (the 1:13 phase) is difficult in bulk La-Fe-Si-based alloys prepared by arc or induction melting To obtain a single 1:13 phase, the bulk alloys have to be subjected to annealing at high temperatures (above 1100 K) for several weeks [2], which limits their practical applications Alternatively, strip casting method has a great potential for kilogram-scale production of high-performance La-Fe-Si-based magnetocaloric materials in a short production cycle [3, 4]. In this study, we have investigated the influence of annealing temperature on the microstructure and magnetic properties of LaFe
₁₁
Co
_0.8
Si
_1.2
(at %) flakes with near room temperature MCE.