Magnetic Refrigeration Technology Research Articles

Ensemble-Based Support Vector Regression with Gravitational Search Algorithm Optimization for Estimating Magnetic Relative Cooling Power of Manganite Refrigerant in Magnetic Refrigeration Application

Magnetic refrigeration technology (MRT) is considered an energy-efficient and environmental-friendly system of refrigeration that has a considerable potential of replacing the classical gas-compression expansion method of refrigeration. Inclusion of manganite-based material (MBM) in MRT as a magnetic refrigerant has attracted significant attention recently due to cost effectiveness of the refrigerant as well as better resistance to oxidation and corrosion as compared to the commonly used metal gadolinium refrigerant. Relative cooling power (RCP) is one of the most important parameters to be considered while assessing the usefulness of MBM. Its value can be altered through doping with external materials and accurate estimation of the dopant influence is required to achieve the right amount of RCP. This present research work proposes support vector regression (SVR) ensemble models with gravitational search algorithm (GSA) hyper-parameters optimization, for estimating RCP of MBM and to determine the influence of dopants on RCP using ionic radii and dopant concentrations as descriptors. GSA-SVR ensemble model (GSE) is developed by employing the outputs of five different SVR models as descriptors while GSA-SVR ensemble model with averaging (GSEA) uses the average of the five different SVR models as its descriptor. The novel ensemble models outperform other SVR models, specifically; GSE performs better than GSA-SVR model and the conventional SVR model with performance improvement of 269.14% and 283.61%, respectively on the basis of root mean square error (RMSE). Furthermore, GSEA outperforms GSE, GSA-SVR model and conventional SVR with performance improvement of 27.51%, 370.70%, and 389.14%, respectively on the basis of RMSE. The developed GSE and GSEA also perform better than the existing RCP model in the literature with performance improvement of 11.53% and 42.21%, respectively. The results of this research work will not only serve to circumvent the experimental challenges of RCP measurement without loss of experimental precision but also further promotes environment-friendly system of refrigeration.

Magnetocaloric Effect of Ni<sub>44</sub>Co<sub>6</sub>Mn<sub>40</sub>Cu<sub>x</sub>Sn<sub>10-x</sub> Quinary Alloy Comes from the Martensitic Transformation

The structure, martensitic transition and magnetic properties of Ni44Co6Mn40CuxSn10-x quinary alloy are investigated systematically. The substitution of Cu for Sn is found to reduce the symmetry of crystal structure, showing an evolution from cubic to tetragonal phase at room temperature. Two magnetic transitions were observed in the alloys, martensitic transition and Curie transition. The critical temperatures of martensitic transformation are found to increase nearly linearly with increasing valence electron concentration caused by Cu substitution for Sn, while Curie temperature of the austenitic phase decreases with the increasing Cu content in the alloys. The Ni44Co6Mn40CuxSn10-x alloys have a large magnetic entropy change across the martensitic transition, reaching 26.8 Jkg-1K-1 under a field change of 3T, because of the strong coupling between structure and magnetism, which shows a great applicable prosperity in magnetic refrigeration technology.

Near-room-temperature magnetocaloric properties of La1−xSrxMnO3 (x = 0.11, 0.17, and 0.19) nanoparticles

The growth of chemically stable magnetic materials showing a magnetic transition near room temperature with a strong magnetocaloric effect is important for the development of room-temperature magnetic refrigeration technology. Single-phase nanoparticles of La1−xSrxMnO3 (x = 0.11, 0.17, and 0.19) (LSMO) materials in the rhombohedral crystal structure with particle sizes between 20 nm and 30 nm were prepared using the sol-gel method. The crystal structure, morphology, magnetic properties and magnetocaloric effect (MCE) were investigated. The ferromagnetic to paramagnetic phase transitions of these nanoparticles are of second order in nature and the transition temperatures (Tc) lie between 284 K and 327 K. The magnetic entropy change (ΔSM) and relative cooling power (RCP) exhibit a linear dependence on the applied magnetic field. All samples show relatively large cooling efficiency with ΔSM,max of 3.26 Jkg−1 K−1 for La0.89Sr0.11MnO3 at 297 K and RCP of 201 Jkg−1 for La0.81Sr0.19MnO3 both measured at H = 30 kOe. These results suggest that the LSMO nanoparticles have potential for room-temperature magnetic refrigeration.

Investigation of structural, magnetic, and magnetocaloric properties of nanocrystalline double perovskite Pr2CoMnO6

We have investigated the structural, magnetic, and magnetocaloric properties of the nanocrystalline double perovskite Pr2CoMnO6 oxide prepared by the sol-gel method. The x-ray diffraction (XRD) using Rietveld refinement shows that the sample under investigation crystallizes into the orthorhombic crystal structure with Pbnm space group. The average crystallite size calculated using Debye-Scherer’s formula was found to be ∼17 nm. The scanning electron microscopy image shows that the particles formed were of almost uniform in size with particle size ∼192 nm. The temperature dependence magnetization data shows that sample has a paramagnetic to ferromagnetic phase transition around 173 K. A series of M-H isotherms were performed at a gap of 10 K around transition temperature. The maximum entropy change (∣ΔSmax∣) was found to be 1.98 Jkg−1 K−1 at a field change of 5 T and relative cooling power (RCP) was calculated to be 110 J kg−1. These obtained values are reasonably high and could be the potential material for magnetic refrigeration technology.

MAGNETIC PROPERTIES AND MAGNETOCALORIC EFFECT OF Fe90-xPrxZr10 RAPIDLY QUENCHED ALLOYS

In this paper, we present the results of studying magnetic properties and magnetocaloric effect of Fe90-xPrxZr10 (x = 1, 2 and 3) rapidly quenched alloys. The alloy ribbons with thickness of about 15 µm were prepared by melt-spinning method on a single roller system. X-ray diffraction patterns of the ribbons manifest their almost amorphous structure. Thermomagnetization measurements show that the Curie temperature of the alloys can be controlled to be near room temperature by changing concentration of Pr (x). When the concentration of Pr is increased, saturation magnetization of the alloys increased from 48 emu/g (with x = 1) to 66.8 emu/g (with x = 2). All the ribbons reveal soft magnetic behavior with low coercive force (Hc < 42 Oe). The magnetic entropy change of the alloys, |∆Sm|max > 0.9 J.kg-1K-1 in magnetic field change DH = 12 kOe, shows large magnetocaloric effect at phase transition temperature. On the other hand, the working temperature range is quite large (dFWHM ~ 70 K) revealing an application potential in magnetic refrigeration technology of these alloys.

Review on Magnetocaloric Effect and Materials

A detailed discussion of magnetocaloric properties of distinct materials is a vital aspect in magnetic refrigeration technology. This review paper deals with all kinds of magnetocaloric materials such as ferromagnetic perovskites, glass ceramics, oxide-based composites and spinel ferrites. The comparative study of magnetocaloric properties revealed that manganites have the potential applications in magnetorefrigeration technology.

Magnetocaloric effect in the layered organic–inorganic hybrid (CH3NH3)2CuCl4**Project supported by the National Natural Science Foundation of China (Grant Nos. 51371193 and 11534015), the Youth Innovation Promotion of the Chinese Academy of Sciences (Grant No. 2013004), and the Science Fund from the Chinese Academy of Sciences (Grant Nos. XDB07030200 and KJZD-EW-M05).

We present a study of magnetocaloric effect of the quasi-two-dimensional (2D) ferromagnet (CH3NH3)2CuCl4 in ab plane (easy-plane). From the measurements of magnetic field dependence of magnetization at various temperatures, we have discovered a large magnetic entropy change associated with the ferromagnetic–paramagnetic transition. The heat capacity measurements reveal an abnormal adiabatic change below the Curie temperature Tc ~ 8.9 K, which is caused by the nature of quasi-2D layered crystal structure. These results suggest that perovskite organic–inorganic hybrids with a layered structure are suitable candidates as working substances in magnetic refrigeration technology.

Nb modified structural, magnetic and magnetocaloric properties of double perovskite Ba2FeMo1−xNbxO6

A systematic study focusing on the effect of Niobium (Nb) doping on the structural, magnetic and magnetocaloric properties of Ba2FeMoO6 samples is presented here. The samples of interest Ba2FeMo1−xNbxO6 (0 ≤ x ≤ 0.4) were prepared using the solid state reaction method and were confirmed to possess a cubic structure with Fm-3m space group using the X-ray diffraction analysis and Rietveld refinement. A second order of ferromagnetic phase transition was recorded in both the pure as well as the Nb doped samples using the temperature dependent magnetization and Arrott plots analysis. The pristine Ba2FeMoO6 (BFMO) sample indicated a spontaneous magnetization (34.6emu/g at 100K) with a relatively sharp magnetic transition at the Curie temperature (TC) of 315K as compared to the doped samples. A magnetic entropy change of 0.93 Jkg−1K−1 at an applied magnetic field of 2.5T was measured for the pure BFMO sample. The doped BFMO samples with Mo partially substituted by Nb however, were observed to effectively modify the TC accompanied by a decrease in magnetization. The results investigated in this work suggest that the magnetic and magnetocaloric properties of the BFMO can be tailored by controlled Nb doping which is of significant importance in order to realize the numerous potential applications of the material in the magnetic refrigeration technology.

Giant reversible magnetocaloric effect in a multiferroic GdFeO3 single crystal

The magnetocaloric properties of single crystalline ${\mathrm{GdFeO}}_{3}$ have been investigated in the temperature range 2--36 K by magnetization and heat-capacity measurements. Remarkably large and reversible magnetic entropy change, $\mathrm{\ensuremath{\Delta}}{S}_{\mathrm{m}}=\ensuremath{-}52.5$ J/kg K, has been observed for a field change of 0--9 T. The adiabatic temperature change, $\mathrm{\ensuremath{\Delta}}{T}_{\mathrm{ad}}$, is also found to be very large, 22 K, slightly above the antiferromagnetic ordering temperature (${T}_{N}^{\text{Gd}}=2.5$ K) of the ${\mathrm{Gd}}^{3+}$ moment, for a field change of 0--8 T. These magnetocaloric parameters remain large down to the lowest temperature measured and are significantly larger than that reported for the other members of rare-earth ($R$) orthoferrites ($R{\mathrm{FeO}}_{3}$) and several potential magnetic refrigerants in the same temperature range. Both $\mathrm{\ensuremath{\Delta}}{S}_{\mathrm{m}}$ and $\mathrm{\ensuremath{\Delta}}{T}_{\mathrm{ad}}$ are also quite large for a small field change. The large values of magnetocaloric parameters suggest that ${\mathrm{GdFeO}}_{3}$ could be considered as a potential refrigerant in low-temperature magnetic refrigeration technology, such as liquefaction of hydrogen in the fuel industry. Moreover, ${\mathrm{GdFeO}}_{3}$ has very low electrical conductivity and exhibits no thermal and field hysteresis in magnetization, fulfilling the necessary conditions for a good magnetic refrigerant.

Magnetic properties and magnetocaloric effect in double Sr2FeMoO6 perovskites

The magnetic properties and magnetocaloric effect in Sr2FeMoO6 compound have been studied using the Monte Carlo simulation. Thermal magnetization and dM/dT of Sr2FeMoO6 are given. The Curie temperatures TC(K) have been obtained. The temperature dependence of the magnetic entropy for a several magnetic field have been also obtained. The field dependence of relative cooling power and magnetic hysteresis cycle of Sr2FeMoO6 have been determined for a several magnetic field and temperatures. The Sr2FeMoO6 might be a promising base for developing the new kinds of magnetic refrigerant as working materials in magnetic refrigeration technology.

Effects of barium deficiency on structural, magnetic and magnetocaloric properties of La0.6Nd0.1Ba0.3−xMn0.9Cr0.1O3 manganites

ABSTRACTWe have investigated the effects of barium deficiency on structural, magnetic and magnetocaloric properties of La0.6Nd0.1Ba0.3−xMn0.9Cr0.1O3 (x = 0, 0.05 and 0.1) manganites prepared using the solid-state reaction. All the studied samples crystallize in the orthorhombic structure phase with Pnma space group. Magnetization versus temperature showed that the samples exhibit a second-order paramagnetic to ferromagnetic transition with a decrease of the Curie temperature (TC) from 275 K for x = 0–235 K for x = 0.1. The increase of barium deficiency leads to the decrease of the maximum magnetic entropy change and relative cooling power values from (4.40 J.kg−1 K−1 and 262.94 J.kg−1, for x = 0) to (2.78 J.kg−1 K−1 and 159.41 J.kg−1, for x = 0.1) for an applied magnetic field μ0H = 5 T. These values are compared favorably with those of some other reported manganites, making our samples promising candidates for the magnetic refrigeration technology.

Modeling of magnetic cooling power of manganite-based materials using computational intelligence approach

Magnetic refrigeration (MR) technology has been identified as a potential replacement for the gas compression system of refrigeration due to its environmental friendliness and high level of efficiency. This technology utilizes manganite-based materials as magnetic refrigerants due to the dependence of magnetic properties as well as relative cooling power (RCP) of this class of materials on the concentration and nature of the dopants. Quantifying the effect of dopants on RCP of manganite-based materials requires a long experimental procedures and techniques that are costly and time-consuming. In order to circumvent these challenges, we propose a model, based on support vector regression (SVR), which quickly estimates the RCP of doped manganite-based materials with high level of accuracy using crystal lattice constants as descriptors. The accuracy and ease with which the proposed SVR-based model estimates RCP of doped manganite-based materials is very promising and effective in designing MR system of desired RCP.

Magnetocaloric Materials with Multiple Instabilities.

The magnetocaloric effect is a well-known phenomenon where the temperature of a magnetic material varies upon application or removal of a magnetic field. This effect is anticipated to be applied to magnetic refrigeration technology, which is environmentally benign. For practical applications, it is essential to explore and expand the materials horizon of novel magnets that exhibit giant magnetocaloric effects to achieve sufficient cooling efficiency. In this article, several attempts to enhance the magnetocaloric effect are reviewed from the viewpoint of the competition or cooperation between the ferromagnetic interaction and other magnetic, electronic, and structural instabilities in strongly correlated materials. The results indicate that both the competition and cooperation between them promote the first-order nature of the magnetic transition, leading to giant magnetocaloric effects. Therefore, exploiting multiple instabilities is a promising strategy for exploring new magnetocaloric materials.

Progress of room temperature magnetic refrigeration technology

refrigeration technology. It has been considered as one of promising alternatives to traditional vapor compression refrigeration technology. Magnetic refrigeration, in which solid magnetic materials instead of gaseous refrigerants are used, is based on the magnetocaloric effect. When magnetocaloric material moves in or out of magnetic field, it releases heat due to magnetization or absorbs heat due to demagnetization, respectively. In this paper, magnetocaloric effects (MCEs) and basic thermodynamic cycles are briefly described at first. Some typical magnetic refrigeration cycles are introduced from the viewpoint of thermodynamics, which include hybrid cycle, cycle based on the active magnetic regenerator and cycle based on the active magnetic regenerator coupled with gas regenerative refrigeration. Specifically, magnetic refrigeration cycle based on the active magnetic regenerator (AMR) coupled with gas regenerative refrigeration is a novel idea that combines the magnetocaloric effect with the regenerative gas expansion refrigeration. And it has been under the way to try to achieve greater refrigeration performance of the coupled refrigerator in the research institutions. Thereafter, the paper reviews the existing different numerical models of AMR refrigerator. Analyzing and optimizing an AMR magnetic refrigerator are typical complicated multi-physics problems, which include heat transfer, fluid dynamics and magnetics. The majority of models published are based on one-dimensional simplification, which requires shorter computation time and lower computation resources. Because a one-dimensional model idealizes many factors important for the system performance, two- or three- dimensional numerical models have been setup. Besides, some key items for the model are described in detail, such as magnetocaloric effect, thermal conduction, thermal losses, demagnetizing effect and magnetic hysteresis. Considering the accuracy, convergence and computation time, it is quite vital for numerical models to choose some influential factors reasonably. Then, the recent typical room magnetic refrigeration systems are listed and grouped into four types, i.e., reciprocating-magnet type, reciprocating-regenerator type, rotary-magnet type, and rotaryregenerators type. Different characteristics of these four types are compared. Reciprocating magnetic refrigerators have the advantages of simple construction and max magnetic field intensity difference. Rotary magnetic refrigerator due to compact construction, higher operational frequency and better performance is deemed as a more promising type, in the progress of magnetic refrigeration technology. Meanwhile there are still some key challenges in the practical implementation of magnetic refrigeration technology, such as the development and preparation technologies of high-performance MCE materials, powerful magnetic circuit system and flowing condition. Finally, possible applications are discussed and the tendency of future development is given.

First principles study of mechanical properties of FeMnP1-xTx (T=Si, Ga, Ge) compounds

Magnetic refrigeration technology is considered as a better alternative to traditional steam compression scheme, since it has many advantages such as environment friendly characteristic, more compact solid refrigerant, low cost, etc. The mechanical stability is of essential importance for serving as magnetic refrigerant materials which work under repeatedly thermal and magnetic cycles. Recent experiment reveals that the polycrystalline FeMnP1-xSix compounds are brittle, and even fracture of samples during post heat treatment is observed. Therefore, the improvement of the ductility of Fe2P-Type FeMn-based magnetocaloric materials becomes an important issue in practical application. So far, there are few studies of the mechanical properties of these compounds. Alloying is an effective method to improve the mechanical properties of single phase materials, and Ga or Ge could be a better choice to replace the Si element. In this paper, we study the mechanical properties of giant magnetocaloric FeMnP1-xTx (T=Si, Ga, Ge) compounds by the projector augmented wave method as implemented in VASP (Vienna ab initio simulation package) in the framework of density functional theory. It is found that the lattice parameter, total energy, magnetic moment, elastic constant and the electronic structure of FeMnP1-xGax compounds are similar to those of FeMnP1-xGex compounds, therefore, it is believed that the FeMnP1-xGax compounds are candidate refrigerant for room temperature magnetic refrigeration. The relatively large single crystalline elastic constants of FeMnP1-xTx (T=Si, Ga, Ge) compounds show that this family of compounds is mechanically stable. This ensures the long-term applicability of FeMnP1-xTx compounds in magnetic refrigeration facilities. For polycrystalline compounds, we calculate their shear moduli and bulk moduli by Hill averaging scheme. And according to Pugh criterion, the ductility or brittleness characteristics of FeMnP1-xTx (T=Si, Ga, Ge) compounds are discussed. All the FeMnP0.67T0.33 (T=Si, Ga, Ge) compounds are ductile, among them, FeMnP0.67Ga0.33 compound shows the best ductility, whereas the ductility of FeMnP0.67Si0.33 compound is the weakest. This result proves that substituting P with Ga could improve the ductility of this class of compound. The mechanical properties of polycrystalline FeMnP0.33T0.67 compounds are close to the ductile/brittle critical point. For FeMnP0.33T0.67 compounds, the T atoms just occupy the 2c sites of metalloid atom in Fe2P-type structure, therefore it is expected that the occupation disorders of P and T atoms at high T concentration could improve the ductility of the compounds according to the result of FeMnP0.67Ga0.33 compound. Finally, the self-consistent elastic constants of different compounds are understood from the calculated electronic density of states and force theorem.

Estimation of Curie temperature of manganite-based materials for magnetic refrigeration application using hybrid gravitational based support vector regression

Magnetic refrigeration (MR) technology stands a good chance of replacing the conventional gas compression system (CGCS) of refrigeration due to its unique features such as high efficiency, low cost as well as being environmental friendly. Its operation involves the use of magnetocaloric effect (MCE) of a magnetic material caused by application of magnetic field. Manganite-based material demonstrates maximum MCE at its magnetic ordering temperature known as Curie temperature (TC). Consequently, manganite-based material with TC around room temperature is essentially desired for effective utilization of this technology. The TC of manganite-based materials can be adequately altered to a desired value through doping with appropriate foreign materials. In order to determine a manganite with TC around room temperature and to circumvent experimental challenges therein, this work proposes a model that can effectively estimates the TC of manganite-based material doped with different materials with the aid of support vector regression (SVR) hybridized with gravitational search algorithm (GSA). Implementation of GSA algorithm ensures optimum selection of SVR hyper-parameters for improved performance of the developed model using lattice distortions as the descriptors. The result of the developed model is promising and agrees excellently with the experimental results. The outstanding estimates of the proposed model suggest its potential in promoting room temperature magnetic refrigeration through quick estimation of the effect of dopants on TC so as to obtain manganite that works well around the room temperature.

Impact of cycle-hysteresis interactions on the performance of giant magnetocaloric effect refrigerants

Magnetic refrigeration technology based on the giant magnetocaloric effect in solid-state refrigerants is known qualitatively to be limited by dissipative mechanisms accompanying hysteresis in the magneto-structural solid–solid phase transition. In this paper, we quantitatively explore the dependence of cycle performance metrics (cooling power, temperature span, work input, and fractional Carnot efficiency) on hysteresis properties (thermal hysteresis, one-way transition width) of the magneto-structural phase transition in a Ni45Co5Mn36.6In13.4 alloy system. We investigate a variety of Ericsson-type magnetic refrigeration cycles, using a Preisach-based non-equilibrium thermodynamic framework to model the evolution of the alloy's magnetic and thermal properties. Performance metrics are found to depend strongly on hysteresis parameters, regardless of the cycle chosen. However, for a given hysteresis parameter set, the material's transformation temperatures determine a unique cycle that maximizes efficiency. For the model system used undergoing Ericsson cycles with and maximum field constraint, fractional Carnot efficiencies in excess of 0.9 require thermal hysteresis below and , respectively. We conclude briefly with some general materials considerations for mitigating these hysteresis inefficiencies through microstructure design and other materials processing strategies.

Magnetocaloric effect and evidence of superparamagnetism inGdAl2nanocrystallites: A magnetic-structural correlation

The correlation between structural and magnetic properties of $\mathrm{GdA}{\mathrm{l}}_{2}$, focusing on the role played by the disorder in magnetic ordering and how it influences the magnetocaloric effect (MCE) are discussed. Micrometric-sized particles, consisting of nanocrystallites embedded in an amorphous matrix, were prepared by a mechanical milling technique and characterized by means of x-ray diffraction, scanning and high-resolution transmission electron microscopy as well as magnetic measurements as a function of an applied external magnetic field and temperature. The results show that the average particle size is just slightly diminished (\ensuremath{\approx}7%) with the milling time (between 3 and 13 h), whereas the average crystallite size undergoes an expressive reduction (\ensuremath{\approx}43%). For long milling times, structural disorders mostly associated with crystallite size singularly affect the magnetic properties, leading to a large tablelike MCE in the temperature range between 30 and 165 K. Below 30 K, nanocrystallites with dimensions below a given critical size cause an enhancement in the magnetic entropy change related to superparamagnetic behavior. In contrast, for low milling times, relative cooling power values are improved. These striking features along with the small magnetic hysteresis observed make the milled $\mathrm{GdA}{\mathrm{l}}_{2}$ a promising material for application in the magnetic refrigeration technology. Finally, a discussion in an attempt to elucidate the origin of the spin-glass states previously reported in the literature for mechanically milled $\mathrm{GdA}{\mathrm{l}}_{2}$ samples for very long times (400 and 1000 h) is presented.

Environmentally Friendly Magnetic Refrigeration Technology Using Ferromagnetic Gd Alloys

Environmentally Friendly Magnetic Refrigeration Technology Using Ferromagnetic Gd Alloys

Research progress in magnetocaloric effect materials

Magnetocaloric effect（MCE) is the intrinsic property of a magnetic material near transition temperature and the magnetic refrigeration based on MCE has been demonstrated as a promising alternative to the conventional gas compression or expansion refrigeration due to its high energy efficiency and environmental friendliness. The development of magnetic refrigeration technology depends on the research progress of magnetic refrigerant materials with large MCEs. Lots of researches of material exploration and material optimization have promoted the progress of magnetic refrigeration technology in recent decades. In this paper, we introduce the basic theory of MCE and the development of refrigeration technology, review the research progress of large MCE materials both in low temperature range and in room temperature range, and specifically focus on the latest progress of some MCE materials. Low temperature MCE materials mainly include those rare earth based materials with low transition temperatures, such as binary alloys（RGa, RNi, RZn, RSi, R3Co and R12Co7), ternary alloys（RTSi, RTAl, RT2Si2, RCo2B2 and RCo3B2), and quaternary alloys（RT2B2C), where R denotes the rare earth and T represents the transition metal. Those materials mainly possess the second-order phase transitions and show good thermal hysteresis, magnetic hysteresis, and thermal conductivities. Room temperature MCE materials are mainly Gd-Si-Ge intermetallic compounds, La-Fe-Si intermetallic compounds, MnAs-based compounds, Mn-based Heusler alloys, Mn-based antiperovskite compounds, Mn-Co-Ge intermetallic compounds, Fe-Rh compounds, and perovskite-type oxides. The above materials usually have the first-order phase transitions and most of these materials possess the large MCEs in room temperature range, therefore they have received much attention home and abroad. Among those room temperature MCE materials, the La-Fe-Si series is considered to be the most promising magnetic refrigerant materials universally and our country has independent intellectual property rights of them. The further development prospects of MCE materials are also discussed at the end of this paper.