Magnetic Refrigeration Applications Research Articles

Influence of synthesis protocol on structure, magnetic and magnetocaloric properties of ErCrO3

In this study, we investigated the morphology, structure, magnetic, and magnetocaloric properties of ErCrO3 (ECO) nanoparticles synthesized through two distinct chemical routes: combustion and hydrothermal methods. X-ray diffraction analysis revealed a well-crystallized orthorhombic pbnm phase in both samples. The broader Raman peaks observed in the hydrothermal sample indicate a larger strain of 0.138%, compared to the combustion-derived sample. A significant reduction in the magnetic phase transition temperature was observed for ECO nanoparticles synthesized via the hydrothermal method (117 K) compared to those derived from combustion (∼130 K), which can be attributed to size-induced strain. The hydrothermal ECO samples exhibited a broader temperature span and lower entropy changes compared to the combustion-derived counterparts. Consequently, we observed an improved relative cooling power of 523 J K−1 and entropy change of −10.8 J kg−1 K−1 at a magnetic field of 50 kOe. These findings are promising for magnetic refrigeration applications. The ability to tailor magnetocaloric properties through straightforward synthesis methods underscores their significance in advancing potential applications.

A numerical comparison of Gd, Pr0.65Sr0.35MnO3 and single LaFeCoSi, for use in room temperature magnetic cooling applications

Abstract One of the most significant scientific difficulties to achieving excellent performance for room-temperature magnetic cooling devices is finding suitable magnetocaloric refrigerants. To contribute to this research field, three kinds of magnetocaloric materials (Gd, Pr0.65Sr0.35MnO3 and single LaFeCoSi) in the same conditions (Curie temperature, applied magnetic field) have been considered to evaluate their potential in the magnetic refrigeration application using a 1D-AMRR (Active-Magnetic-Refrigeration-Regenerator) cycle with a parallel plate regenerator. In this way, four cooling performance parameters were investigated, namely the temperature span, the cooling power, the exergy, and the coefficient of performance. The temperature span was found to be 11.79K for Gd , 8K for LaFeCoSi and 4.47 K for Pr0.65Sr0.35MnO3. The obtained numerical results reveal that the Gd-based AMR system displays a higher efficiency, while the Pr0.65Sr0.35MnO3-based AMR system exhibits a smaller one. The magnetocaloric effect (MCE) in the magnetic refrigerants was considered to explain the result obtained and can be considered as one of the main factors to enhance the magnetic refrigeration performance.

Observation of Griffiths phase and giant magnetocaloric effect in double perovskite oxide RE2FeCrO6 (RE = Gd, Tb, Dy, Er)

AbstractThe magnetic properties of double perovskite oxide RE2FeCrO6 (RE = GD, Tb, Dy, Er) were systematically studied, and the Griffiths phase evolution was observed. In Tb2FeCrO6, Dy2FeCrO6, and Er2FeCrO6, there are antiferromagnetic (AFM)‐ferromagnetic (FM) first‐order phase transition and the Griffiths phase with coexistence of FM and paramagnetic (PM) was observed by the EPR spectra. Gd2FeCrO6 has an AFM–PM second‐order phase transition, and there is no first‐order phase transition in the range of ∆H = 0–50 kOe. As the temperature decreases, all four sets of samples present χ−1 (T) deviates downwards from the Curie–Weiss linear behavior from 0.2 to 5 kOe, corresponding to the typical characteristics of Griffiths phase evolution. In addition, all four sets of samples have excellent magnetocaloric performance. Especially, the Gd2FeCrO6 oxide has giant magnetic entropy change and relative cooling power (−∆SMmax = 30.31 J/kg K and RCP = 312.8 J/kg when ∆H = 50 kOe). From the perspective of low‐temperature magnetic refrigeration application, the present work provides important candidate references for magnetic component researchers.

On the nonmagnetic atom disorder influence in the magnetic and magnetocaloric properties of the Er2Cu0.92Si2.76 off-stoichiometric single-phase compound

This paper presents and discusses material aspects, as well as the magnetic and magnetocaloric properties of nominal Er2Cu0.92Si2.76 alloy synthesized by arc melting. The stoichiometric alloy, prepared with a precise 2(Er):1(Cu):3(Si) ratio, adopts dual symmetries manifesting AlB2-type hexagonal and ThSi2-type tetragonal structures. It was observed that stoichiometric deviations by reducing both Cu/Si concentrations imply a decrease in the tetragonal phase fraction. An 8 % reduction in Cu and Si contents leads to the formation of an off-stoichiometric single-phase: the Er2Cu0.92Si2.76 phase - the focus of this investigation. Notably, Er2Cu0.92Si2.76 showed a uniform grain microstructure without porous and with a homogeneous elemental composition. On the other hand, a long-range antiferromagnetic ordering around 5.6 K was noticed, with a weak influence of magnetic frustration likely arising from nonmagnetic atomic disorder and vacancy at the Cu/Si site. An external magnetic field (greater than 10 kOe) induces ferromagnetic-like ordering, with a saturation tendency at ≈ 50 kOe, corresponding to half the expected magnetic moment for fully ordered Er3+ ions. Er2Cu0.92Si2.76 exhibits large magnetocaloric properties, with isothermal entropy change and relative cooling power values reaching 14.6 J/kgK and 312 J/kg, respectively, for a magnetic field change of 50 kOe. The absence of magnetic and thermal hysteresis is also an attractive prospect for this material aimed at magnetic refrigeration applications at low temperatures.

Structure, Optical Properties and Magnetocaloric Effects in Gd3Fe5O12 Garnet Synthesized by Solid State Method

In this work, gadolinium iron garnet (Gd3Fe5O12) was synthesized using the solid-state ceramic method. The structural analysis, confirmed through Rietveld refinement, indicated the formation of a single-phase garnet structure. Scanning electron microscopy studies revealed uniform grain size and homogeneity in the sintered material, while UV-vis absorption studies showed a peak at 300 nm, indicating strong ultraviolet interaction and an optical band gap of 3.64 eV, suggesting optoelectronic potential. The fluorescence emission spectrum shows a band at 435 nm, while the excitation spectrum exhibits bands at 275 and 360 nm. The magnetic measurements demonstrated Gd ion ordering at low temperatures, with a compensation temperature around 290 K. Arrott plots confirmed the second-order magnetic phase transition. Importantly, Gd3Fe5O12 exhibited both normal and inverse magnetocaloric effects, with a maximum magnetic entropy change of 1.05 J kg–1 K–1 at 230 K under 9 T magnetic field. These properties indicate Gd3Fe5O12 material as a promising candidate for magnetic refrigeration and optoelectronic applications.

Magnetic properties and magnetocaloric effect in thiospinel Fe1-xCuxCr2S4 (x = 0.0, 0.5) compounds

In this study, we investigate the magnetic and magnetocaloric properties of Cr-based spinel sulphides Fe1-xCuxCr2S4 (x = 0.0 and x = 0.5). The magnetic transition temperature of FeCr2S4 (176 K) increases to 330 K when 50 % of Fe in FeCr2S4 structure is substituted with Cu. Temperature-dependent Zero-Field-Cooled (ZFC) and Field-Cooled (FC) magnetic moment measurements show a paramagnetic (PM) to ferrimagnetic (FiM) phase transition in our samples. Magnetocaloric properties were investigated through magnetization isotherm measurements. The maximum magnetic entropy change values are −2.78 J/kg. K and −2.11 J/kg. K under 5 T magnetic field, for x = 0 and x = 0.5 in Fe1-xCuxCr2S4, respectively. Analysis of phenomenological universal curves and Arrott plots indicate a second-order magnetic transition for both compounds. Consequently, Fe0.5Cu0.5Cr2S4 emerges as a promising candidate for magnetic refrigeration applications due to its considerable high magnetic entropy change and its proximity to room temperature transition.

Enhanced magnetocaloric effect in nano-sized Dy3Ga5O12 garnet: A comparative study on the effect of solid-state and wet-chemical synthesis

This study investigates the magnetic and structural properties of bulk and nanosized Dy3Ga5O12 (DGG) synthesized through solid-state and wet chemical methods to assess the impact of particle size. The single-phase composition of the synthesized materials was determined by X-ray diffraction analysis (XRD). XRD and TEM analysis revealed the formation of nanosized DGG via the wet chemical route at 750 °C/2h. The nano DGG exhibits enhanced magnetocaloric effect compared to its bulk counterpart, suggesting its potential as a promising material for low-temperature magnetic refrigeration applications.

Hysteresis behavior and magnetocaloric effect in MnNiGa[formula omitted] full-Heusler alloy

In this manuscript, we studied the magnetic, magnetocaloric, and hysteresis properties of the MnNiGa2 full-Heusler alloy using mean-field theory and first-principles calculations. Initially, we employed the GGA+U method to investigate the structural characteristics of the alloy. Our findings indicated that the ferromagnetic state, with an optimal lattice parameter of 5.88 Å, was the most stable compared to the antiferromagnetic states. Additionally, the exchange interactions, defined as the Hamiltonian parameters of the studied system, were calculated and used in the mean-field approximation. The second-order transition at a Curie temperature of Tc = 373 K, previously revealed experimentally, has been confirmed. Furthermore, the alloy exhibited a relative cooling power (RCP) of 260.43 J/kg and a magnetocaloric effect of 10.34 J/kg.K at an applied magnetic field of 1.4 T. These results suggest that MnNiGa2 is a promising candidate for magnetic refrigeration applications.

Polar phonons features and intrinsic dielectric properties of RE2CoMnO6 (RE = Tb, Dy, Ho, Tm and Yb) double perovskites

RE-based double perovskite (DP) oxides of the RE₂TMTM'O₆ family exhibit intriguing magnetodielectric (MD) properties and magnetocaloric effects (MCEs), making them promising candidates for applications in high-performance supercapacitors, memories, spintronic devices, and cryogenic magnetic refrigeration. This paper addresses the vibrational properties of RE2CoMnO6 (RE = Tb, Dy, Ho, Tm, and Yb) ceramics for the first time using infrared reflectance spectroscopy. The dielectric merit factors in the microwave (MW) range, including the quality factor (Qu) and the static dielectric constant (ɛ0), were estimated. It was observed that the intrinsic dielectric constants decrease from approximately 26.2 to 14.4 as the rare earth ionic radius decreases. The mean values of these compounds suggest their suitability for applications in MW circuitry devices.

Effect of polymer coating on magnetocaloric properties of garnet

In this study, Gd3Fe5O12 nanoparticles were synthesized using the sol–gel autocombustion method and subsequently coated with polyvinylpyrrolidone (PVP) polymer. The study focuses on understanding the influence of PVP coating on garnet particles’ magnetic and magnetocaloric properties. The crystallite size upon PVP-coating remained unaltered, but the grain size and surface area of coated particles increased. The magnetization of PVP-coated particles decreased by around 11% as compared to the uncoated particles at 5 K. Mössbauer and photoelectron spectroscopy confirmed the presence of a paramagnetic phase Fe3+ in the PVP-coated nanoparticles responsible for the reduction in magnetization value. The maximum value of magnetic entropy change (−ΔS m ) for uncoated Gd3Fe5O12 was 3.78 Jkg−1 K−1 at 37.5 K with a 5T applied field, accompanied by a relative cooling power (RCP) of 382 Jkg−1. On the other hand, for PVP-coated Gd3Fe5O12, the maximum −ΔS m was 3.38 Jkg−1 K−1 at 57.5 K with a 5T applied field, and the RCP was 308 Jkg−1. The observed maximum magnetic entropy changes at higher temperatures for the PVP-coated Gd3Fe5O12 sample are noteworthy. This characteristic indicates that the PVP-coated garnet may have an advantage in terms of usability over a wider temperature range compared to the uncoated counterpart, which can potentially be a promising material for applications in cryogenic temperature magnetic refrigeration.

Inverse and conventional dual magnetocaloric effects in Ni substituted Y-type Sr2Zn2-xNixFe12O22 hexaferrites

The effects of Ni substitution on magnetic and magnetocaloric effect (MCE) are investigated in polycrystalline Y-type hexaferrites of Sr2Zn2-xNixFe12O22 (x = 0.0, 0.8, and 2.0). With the increasing of temperature, the M-T curves indicate successive magnetic structure transitions exist in Sr2Zn2-xNixFe12O22 (x = 0.0, 0.8, and 2.0), which play significant roles in MCE behaviors. As the Ni2+ doping ratio increases, the shape of −ΔSM−T curves near room temperature evolves gradually from a table-like to a peak-like form. Particularly, a significant contrast between CMCE and IMCE is observed below 100 K, whose behavior can be inherently exploited for heat sink in magnetic refrigeration applications. Among the samples in this series, Sr2Zn1.2Ni0.8Fe12O22 plays the best CMCE and IMCE performances, with the maximum magnetic entropy change (−ΔSMmax) values of 0.78 J/kg K at 354 K and −0.56 J/kg K at 16 K for ΔH=50kOe , respectively. Our work demonstrates that Sr2Zn2-xNixFe12O22 hexaferrites have great potential to be tailored for magnetic refrigeration with special needs such as different operating temperature zones, Ericsson cycle or heat sink at refrigeration.

Low-temperature magnetic refrigeration in Gd20Tb20Er20Al20M20 (M = Fe, Co) high-entropy metallic glasses

This paper focuses on the magnetocaloric effect (MCE) of Gd20Tb20Er20Al20M20 (M = Fe, Co) high-entropy metallic glasses (HE-MGs). XRD and TEM results indicate that both HE-MGs are amorphous. Magnetic studies show that both HE-MGs display spin-glass behavior, undergo a second-order phase transition from ferromagnetic to paramagnetic, and exhibit soft magnetic properties at the Curie temperature (TC). Notable large and broad table-like magnetic entropy change characteristics of Gd20Tb20Er20Al20Fe20 (Gd20Tb20Er20Al20Co20) appear near a TC of 92 (51) K. Hence, under 7 T magnetic field, |-∆SMmax|, ∆ TFWHM, and RCP are 7.83 (10.10) J·kg-1·K-1, 120.07 (71.88) K, and 1008.26 (805.70) J·kg-1, respectively. Furthermore, the modulation of the magnetic and magnetocaloric properties of the samples after substitution of Fe for Co was revealed by the intricate 3d-3d and 3d-4f exchange interactions within the system. The magnetic phase transition critical behaviors in both HE-MGs were analyzed using the scaling law to clarify the deviation of amorphous materials from the mean-field theory. Thus, this study not only highlights the potential of this material for low-temperature magnetic refrigeration applications, but also expands our understanding of its physical properties.

Crystal structure, magnetic property and cryogenic magnetocaloric effect of Gd4Al2O9 aluminate

Developing magnetic materials with excellent magnetocaloric effect (MCE) is a vital prerequisite for practical magnetic refrigeration (MR) applications. Herein, a single-phased polycrystalline Gd4Al2O9 compound was fabricated using the co-precipitation method, and its structure, magnetic property together with magnetocaloric performance were investigated. The Gd4Al2O9 compound was found to crystallize in the monoclinic structure space group P21/c with lattice parameters a = 7.4852 Å, b = 10.5561 Å, c = 11.1774 Å, β = 108.95° and V=835.3107 Å3, and the constituent elementals had valence states of Gd3+, Al3+ and O2−. Excellent comprehensive MCE performance was observed for the Gd4Al2O9 compound in low-temperature regions. The obtained values of maximal magnetic entropy change, temperature-averaged entropy change (3 K) and relative cooling power under the magnetic flux density change of 0–7 T are 26.31 J/kg·K, 25.09 J/kg·K and 317.05 J/kg. The Gd4Al2O9 compound shows impressive comprehensive MCE performances compared with some recently reported rare earth-based MR materials with prominent performances, meaning that it is a suitable candidate material for low-temperature MR applications.

Large magnetocaloric effect of RCoSn (R=Dy, Ho, Er and Tm) compounds

Materials with large magnetocaloric effect (MCE) at low temperatures under low field changes play an important role in the application of cryogenic magnetic refrigeration and attract extensive research interests of researchers. In this work, four ternary rare-earth-based RCoSn (R=Dy, Ho, Er and Tm) compounds were successfully synthesized and the crystal structure, magnetic properties, magnetic phase transition, and magnetocaloric effects were systematically studied. RCoSn (R=Dy, Ho, Er and Tm) compounds all crystallize in orthorhombic TiNiSi-type structure and undergo an antiferromagnetic (AFM) to paramagnetic (PM) transition with Neél temperature of 11.0, 7.9, 4.9 and 3.0 K, respectively. Large cryogenic MCE of RCoSn (R=Dy, Ho, Er and Tm) with the maximum magnetic entropy change (−ΔSMmax) of 10.6, 13.7, 17.1, 13.4 J/kg K for field change of 0–5 T was obtained. Furthermore, the value of −ΔSMmax for ErCoSn and TmCoSn is as high as 11.3 and 10.1 J/kg K for field change of 0–2 T, which is very competitive among low temperature magnetocaloric materials. The characteristic of second order magnetic phase transition indicates RCoSn (R=Dy, Ho, Er and Tm) compounds have good magnetic/thermal reversibility. These results show that RCoSn compounds, especially ErCoSn and TmCoSn, exhibit promising MCE and have great application potential in cryogenic magnetic refrigeration.

Near-room-temperature magnetic properties and magnetocaloric effect of polycrystalline and nano-scale manganites Pr(0.65-x)NdxSr0.35MnO3 (x ≤ 0.35)

Here we report investigations of structural, electrical and magnetic properties of bulk and nano-sized Pr0.65-xNdxSr0.35MnO3 compounds (x ≤ 0.35). Polycrystalline compounds were produced by solid – state reaction and nanocrystalline samples were obtained by sol–gel method. Analysis of x-ray diffraction patterns revealed a change in lattice structure from ‘Pbnm’ to ‘R3c’ symmetry, with diminishing cell volume upon increasing Nd ions substitution for all samples. Optical microscopy was used for bulk surface morphology and transmission electron microscopy was implemented for nano-sized samples. Iodometric titration showed oxygen deficiency for bulk compounds and oxygen excess for nano-sized particles. Measurements of resistivity of bulk samples revealed a single peak at temperatures associated with grain boundary conditions and with ferromagnetic/paramagnetic transition and negative magnetoresistivity. Critical magnetic behavior analysis disclosed that the polycrystalline samples are governed by a tricritical mean field and by 3D Heisenberg models while nanocrystalline samples are governed by a mean field model. Curie temperature Tc values remain in near room temperature range for all bulk compounds; they lower with increasing Nd ions substitution from 295 K for the parent bulk compound to 268 K for x = 0.35. Tc is lowered from 255 K for the parent nano-sized compound in small temperature intervals. All compounds exhibit second-order magnetic phase transitions and relatively high magnetic entropy change, with the highest value of 5.74 J/kgK for x = 0.25 bulk sample in μ˳∆H = 4 T. Strong magnetocaloric effect, stability and the possibility of fine-tuning Tc by Nd ions substitution make the investigated bulk polycrystalline compounds promising for application in magnetic refrigeration. Nano-sized samples possess lower magnetic entropy changes of maximum 2.4 J/kgK in μ˳∆H = 4 T for x = 0.15, but wider effective entropy change temperature (δTfwhm) and relative cooling power on par with other manganites, bringing them into the conversation as a viable option in cooling materials.

The structural, electronic and magnetic properties of [formula omitted] anti-perovskite

A comprehensive exploration of the structural, electronic, and magnetic attributes of anti-perovskite Fe3ZnC carbides was carried out using Density Functional Theory (DFT) and Monte Carlo Simulation (MCS). These anti-perovskite materials possess a unique structure where cation and anion positions are interchanged within the perovskite framework. Our study involves a comparative analysis of the electronic band structures and density of states (DOS) for Fe3ZnC, considering prior theoretical and experimental research. Understanding these anti-perovskite materials' band structures and DOS is pivotal for their effective utilization in magnetic sensors and magnetic refrigeration applications. Our results indicate that Fe3ZnC displays ferromagnetic metallic behavior, particularly when applying the Generalized Gradient Approximation (GGA). Notably, there is a significant overlap between the valence (VB) and conduction (CB) bands. Furthermore, MCS predicts a second-order ferromagnetic-to-paramagnetic transition in the anti-perovskite Fe3ZnC compound, characterized by a notably high Curie temperature. These insights advance our understanding of these materials, paving the way for their effective utilization in magnetic technologies.

Enhanced magnetocaloric and cold storage properties in HoCu2-xNix (x=0.05–0.5) compounds for hydrogen liquefaction

Based on first-principle calculations and experiments, the electronic structure, magnetism, magnetocaloric effect and cold storage properties of HoCu2-xNix (x=0.05–0.5) compounds have been investigated. The theoretical calculations revealed that the magnetic interactions of the HoCu2-xNix compounds were gradually transformed to ferromagnetic states when the Ni element was added above 0.0625. In addition, the Ni element leads to a decreasing Fermi energy level, which results in a significant enhancement of orbital hybridization around the Fermi surface, which may be responsible for the magnetic jump. The magnetic phase transition temperatures of the HoCu1.75Ni0.25 and HoCu1.5Ni0.5 compounds are 14.4 K and 26.0 K, respectively. The ferromagnetic state transition is responsible for the excellent magnetocaloric effect of the HoCu2-xNix compounds under low magnetic fields. The maximum magnetic entropy changes of the HoCu1.75Ni0.25 and HoCu1.5Ni0.5 compounds were 14.7 J/kg K and 11.5 J/kg under varying magnetic fields from 0 to 2 T. In addition, the Ni element make the HoCu2 compound exhibit more excellent cold storage capability. The peak of specific heat capacities of HoCu1.75Ni0.25 and HoCu1.5Ni0.5 compounds were 0.6 J/cm−3K−1 and 0.9 J/cm−3K−1 under 0 T. The present results indicate that HoCu2-xNix (x=0.05–0.5) compounds have promising applications in cryogenic cold storage and magnetic refrigeration.

First-principle calculations of magnetic properties of Ho6(Fe, Mn)Bi2 compounds

The magnetic properties of Ho6MnBi2 and Ho6FeBi2 crystals are investigated by means of density functional theory. These materials are currently an active subject of research in the context of magnetic refrigeration applications since they exhibit a remarkable magnetocaloric effect. In this work, the equation of state, density of states and magnetic moments are calculated and compared with previous experimental results for these materials. Also, the Curie temperatures for the paramagnetic to ferromagnetic phase transition observed in these systems are calculated from first principles. All the calculated quantities are in reasonable agreement with experimental data, which suggests that density functional theory could provide a reliable framework to theoretically investigate the magnetic properties of intermetallic ternary compounds.Graphical abstract

Insights into reduction of hysteresis in (Mn, Fe)2(P, Si) compounds by experimental approach and Landau theory

The giant magnetocaloric effect in (Mn, Fe)2(P, Si) based alloys arises from a magnetoelastic ferromagnetic-paramagnetic (FM-PM) phase transition accompanied by a large thermal hysteresis. The thermal hysteresis leads to an undesirable irreversibility of the magnetocaloric effect (MCE) during cyclic operation, impeding the practical application in solid-state magnetic refrigeration. Here, we present pre-existing PM nuclei play a role in reducing hysteresis. A combinatorial analysis, using in situ X-ray diffraction (XRD) and magneto-optical Kerr effect (MOKE) microscopy, reveals that the residual PM phases at the ferromagnetic state of the compound acts as the nuclei for the growth of the PM phases. This is kinetically favorable for the FM-PM phase transition and contributes to a smaller hysteresis from an extrinsic perspective. In addition, the smaller changes in the lattice constants during the phase transition indicates a weakened first-order phase transition. Through a combined effect of intrinsic and extrinsic contributions, a giant MCE in the magnetic entropy change of 16 J kg–1 K−1 under 2 T and a low thermal hysteresis of 3.0 K were achieved in a basic Mn–Fe–Si–P quaternary system for room temperature applications. Furthermore, based on Landau theory and experimentally obtained data, we established an H-T phase diagram and unveiled the crucial role of the magnetoelastic coupling in manipulating thermal hysteresis. Overall, the findings in this work offer a strategy to mitigate hysteresis while retaining a large MCE through extrinsic control.

Effects of Fe substitution for Mn on structural, magnetic and magnetocaloric properties of TbMn2-xFexSi2

The structural and magnetic properties of TbMn2-xFexSi2 compounds (x = 0.0–0.4) have been investigated in details by high-resolution synchrotron x-ray and neutron powder diffraction, specific heat, and dc magnetization measurements. The replacement of Fe for Mn in TbMn2-xFexSi2 does not change the crystal structure but leads to a significant contraction of the unit cell (dV/dx ∼ - 6 Å3) and modification of three magnetic phase transition temperatures – the Curie temperatures Tc1, Tc2 and the Néel temperature TN. For example, the Tc1, Tc2 and TN values of TbMn2Si2 decrease from Tc1 = 50 K, Tc2 = 64 K and TN = 500 K to Tc1 = 27 K, Tc2 = 37 K and TN = 440 K for TbMn1.6Fe0.4Si2. Detailed neutron diffraction investigations have allowed us to determine the magnetic structures and construct the magnetic phase diagram as well as confirm the presence of magnetoelastic coupling effects. The significantly different responses of Tc1 and Tc2 to applied magnetic fields (e.g. dTc1/dB = 0.52 K/T and dTc2/dB = 4.7 K/T for TbMn1.6Fe0.4Si2), leads to expansion of the temperature region (ΔT = Tc2- Tc1) for the canted ferromagnetic state Fmc-ii between Tc1 and Tc2. In the case of TbMn1.6Fe0.4Si2, ΔT increases from ΔT = 9 K for applied magnetic field B = 0.2 T to ΔT = 36 K for B = 6 T, resulting in plateau-like behaviour of magnetic entropy change and enhances the relative cooling power (RCP) in this system. Under a change of magnetic field of 0 T – 5 T, the maximum value of the magnetic entropy changes -ΔSmax and adiabatic temperature change, ΔTad are derived to be -ΔSmax = 13.1 J/kg K and ΔTad = 8.4 K with the RCP = 411 J/kg for x=0.4 sample. The plateau-like magnetocaloric effect and relatively large RCP make these materials potentially suitable for application in cryogenic magnetic refrigeration.