Magnetocaloric effect: From materials research to refrigeration devices

Systematic study of the microstructure, entropy change and adiabatic temperature change in optimized La–Fe–Si alloys

Over the last two decades, the research activities on magnetocalorics have been exponentially increased, leading to the discovery of a wide category of materials including intermetallics and oxides. Even though the reported materials were found to show excellent magnetocaloric properties on a laboratory scale, only a restricted family among them could be upscaled toward industrial levels and implemented as refrigerants in magnetic cooling devices. On the other hand, in the most of the reported reviews, the magnetocaloric materials are usually discussed in terms of their adiabatic temperature and entropy changes (ΔTad and ΔS), which is not enough to get more insight about their large scale applicability. In this review, not only the fundamental properties of the recently reported magnetocaloric materials but also their thermodynamic performance in functional devices are discussed. The reviewed families particularly include Gd1-xRx alloys, LaFe13-xSix, MnFeP1-xAsx, and R1-xAxMnO3 (R = lanthanide and A = div...

Advanced materials for magnetic cooling: Fundamentals and practical aspects

Over the last two decades, the research activities on magnetocalorics have been exponentially increased leading to the discovery of a wide category of materials including intermetallics and oxides. Even though the reported materials were found to show excellent magnetocaloric properties on laboratory scale, only a restricted family among them could be upscaled toward industrial levels and implemented as refrigerants in magnetic cooling devices. On the other hand, in the most of reported reviews, the magnetocaloric materials are usually discussed in terms of their adiabatic temperature and entropy changes, which is not enough to get more insight about their large scale applicability. In this review, not only the fundamental properties of recently reported magnetocaloric materials are discussed but also their thermodynamic performance in functional devices. The reviewed families particularly include Gd1-xRx alloys, LaFe13-xSix, MnFeP1-xAsx and R1-xAxMnO3 based compounds. Other relevant practical aspects such as mechanical stability, synthesis and corrosion issues are discussed. In addition, the intrinsic and extrinsic parameters that play a crucial role in the control of magnetic and magnetocaloric properties are regarded. In order to reproduce the needed magnetocaloric parameters, some practical models are proposed. Finally, the concepts of the rotating magnetocaloric effect and multilayered magnetocalorics are introduced.

Advanced materials for magnetic cooling:fundamentals and practical aspects

First-principles calculations of magnetic exchange parameters of the austenitic and martensitic phases of Ni-Mn-Ga allow one to characterize this Heusler system across the phase diagram in agreement with experimental trends. The ab initio investigations have been combined with Monte Carlo simulations for a detailed description of the magnetic, martensitic, and magnetocaloric properties of ${\text{Ni}}_{2+x}{\text{Mn}}_{1\ensuremath{-}x}\text{Ga}$ $(0.18\ensuremath{\le}x\ensuremath{\le}0.27)$ Heusler alloys, which undergo a first-order magnetostructural phase transition. For these alloys, the calculated temperature dependence of the magnetic and lattice contributions to the total specific heat as well as the evaluation of the isothermal magnetic entropy $\ensuremath{\Delta}{S}_{mag}(T,{H}_{ext})$ and adiabatic temperature $\ensuremath{\Delta}T(T,{H}_{ext})$ changes around the magnetostructural transition in an external magnetic field agree fairly well with the experimental data. In particular, results for $\ensuremath{\Delta}{S}_{mag}(T,{H}_{ext})$ and $\ensuremath{\Delta}T(T,{H}_{ext})$ may be used to speculate about designing new magnetic Heusler alloys with better magnetocaloric properties, i.e., larger $\ensuremath{\Delta}T(T,{H}_{ext})$ values.

First-principles and Monte Carlo study of magnetostructural transition and magnetocaloric properties of Ni 2 + x Mn 1 − x Ga

Phase formation with NaZn13 structure in metamagnetic La(Fe1–xCox)11.9Si1.1 compounds

Magnetocaloric effects of Ni2.15Mn0.85−xCuxGa (x=0.05,0.07) alloys were investigated with both experimental and theoretical approaches. The experiments show that these alloys have large entropy changes and refrigeration capacities with the field change of 2T. Further theoretical analysis indicates that both magnetic entropy changes and lattice entropy changes have the same sign during heating, while the main entropy change arises from the magnetic entropy change.

Experimental and theoretical investigations of the magnetocaloric effect of Ni2.15Mn0.85-xCuxGa (x= 0.05,0.07) alloys

Effect of praseodymium and cobalt substitution on magnetic properties and structures in La(Fe1-xSix)13 compounds

Microstructure and magnetocaloric effects in LaFe10.8Co0.7Si1.5C0.2 compound produced by induction furnace were investigated. NaZn13-type structure (1:13) formed in LaFe10.8Co0.7Si1.5C0.2 compound after being annealed at 1373 K for only 6 h. As annealing time increases, the grains grow up irregularly. A nearly single 1:13 phase is obtained after being annealed for 2 days. Annealing time is significantly reduced compared with that in conventional bulk LaFe13−xSix compounds. The short annealing time is of great advantage to application. The maximum magnetic entropy change of this compound is −4.9 J/K Kg under a magnetic field of 2 T and relative cooling power is 172.2 J/Kg.

Bo Bao

Papers

Phase formation with NaZn13 structure in metamagnetic La(Fe1–xCox)11.9Si1.1 compounds

Experimental and theoretical investigations of the magnetocaloric effect of Ni2.15Mn0.85-xCuxGa (x= 0.05,0.07) alloys

Effect of praseodymium and cobalt substitution on magnetic properties and structures in La(Fe1-xSix)13 compounds

The study on the microstructure and the magnetocaloric effects in LaFe10.8Co0.7Si1.5C0.2 compound at different annealing times

Enhancement of magnetocaloric effects in La0.8R0.2(Fe0.919Co0.081)11.7 Al1.3 (R=Pr, Nd) compounds