Magnetocaloric Properties Research Articles

Effects of Mg Substitution on the Structural with Rietveld Analysis, Magnetic and Magnetocaloric Properties of Ni-Cu-Cd Bulk Ceramics

Bulk ceramics with optimized density are highly prioritized over ferrite nanoparticles to fabricate devices for their optimal magnetic saturation, lower coercivity, and anisotropy, enhanced resistance, etc. To achieve such bulk specimen using Ni0.5-yMgyCu0.2Cd0.3Fe2O4 disc samples are sintered at 1423 K keeping the heating and cooling rate at 10 K and 5 K respectively. In due course, structural as well as theoretical Rietveld analysis, optical, and magnetic properties have been analyzed using these bulk samples. XRD has explored structural properties and after that these values have analyzed with the Rietveld refinement procedure and obtained goodness of χ2 (1–2) value and other parameters such as lattice parameters, crystal structures, cation distribution, and maximum entropy mapping. Surface morphology and grain size have examined from the as-grown surface without further polishing and annealing by electron microscopy and revealed a decreasing trend of grain size 6.1 µm to 4.2 µm. UV–Vis spectroscopy characterization ensured optical properties for bulk as well as nanopowders and the band gap has been found in the range of 1.4 to 1.6 eV and is increasing with Mg content. Magnetic hysteresis loop exhibits a less decreasing nature up to y = 0.3 of magnetic saturation along with the Law of Approach to saturation which compiles magnetic anisotropy. The temperature-dependent magnetization curves exhibit a sharp decreasing value (i.e. dM/dT maximum) at Curie point, decreasing from 630 K to 505 K with increasing Mg content. At.3 T magnetic field the changes in relative cooling power value have been found in the range 53.82Jkg-1 to 37.79Jkg-1 which could be considered as potential for magnetocaloric refrigeration.

In Situ Fabrication of Electrospun Magnetic Film Under Laparoscopic Guidance for Preventing Postoperative Recurrence of Hepatocellular Carcinoma.

Despite laparoscopic-guided minimally invasive hepatectomy emerging as the primary approach for resecting hepatocellular carcinoma (HCC), there's still a significant gap in suitable biomaterials that seamlessly integrate with these techniques to achieve effective hemostasis and suppress residual tumors at the surgical margin. Electrospun films are increasingly used for wound closure, yet the employment of prefabricated electrospun films for hemostasis during minimally invasive HCC resection is hindered by prolonged operation times, complexity in implementation, limited visibility during surgery, and inadequate postoperative prevention of HCC recurrence. In this study, we integrated montmorillonite-iron oxide sheets into the PVP polymer framework, enhancing the resulting electrospun polyvinylpyrrolidone (PVP) /montmorillonite-iron oxide (MI) film (abbreviated as PMI) with robustness, hemostatic capability, and magnetocaloric properties. In contrast to the in vitro prefabricated electrospun films, the electrospun PMI film is designed to be formed in situ on liver wounds under laparoscopic guidance during hepatectomy. This design affords superior wound adaptability, facilitating meticulous wound closure and expeditious hemostasis, thereby simplifying the operative process and ultimately alleviating the workload of healthcare professionals. Moreover, when exposed to an alternating magnetic field, the film can efficiently ablate residual tumors, significantly augmenting the treatment efficacy of HCC. This article is protected by copyright. All rights reserved.

Magnetic properties and magnetocaloric performances in the (Dy0.25Ho0.25Er0.25Tm0.25)2Cu2In high-entropy compound

We herein fabricated the (Dy0.25Ho0.25Er0.25Tm0.25)2Cu2In high-entropy (HE) compounds and systematically determined its structural, magnetic, and magnetocaloric properties. The (Dy0.25Ho0.25Er0.25Tm0.25)2Cu2In HE compound was found to crystalize in a tetragonal Mo2B2Fe type structure (P4/mbm space group) and undergoes typical second order type magnetic transition. Large MCE and prominent cryogenic magnetocaloric performances were observed in (Dy0.25Ho0.25Er0.25Tm0.25)2Cu2In HE compound. The evaluated values of magnetic entropy change and refrigerant capacity of (Dy0.25Ho0.25Er0.25Tm0.25)2Cu2In HE compound under magnetic field change of 0–7 T are 17.1 J/kgK and 398.0 J/kg which are comparable with the reported candidate materials for cryogenic magnetic cooling, making the present (Dy0.25Ho0.25Er0.25Tm0.25)2Cu2In HE compound also considerable for practical applications.

EXPLORING THE INFLUENCE OF B-SITE DOPANTS ON STRUCTURAL AND MAGNETIC PROPERIES IN La0.8Ag0.2Mn1-XCoxO3 (x: 0 and 0.1) COMPOUNDS

This study examines the structural, electrical, magnetic, and magnetocaloric properties of La0.8Ag0.2Mn0.9A0.1O3 (A: Mn, and Co) compounds under doping in the B-site. XRD results show that the compound containing Co ions directly replaced Mn ions in the B-site without forming a secondary phase containing higher metallic Ag impurities. The data obtained using Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), the temperature dependence of magnetization (M-T), the magnetic field dependence of magnetization (M-H), and the magnetic entropy change (SM) analysis reveal the effect of the doped element on the magnetic properties of the compounds due to the changes they create in the structural and Mn3+/Mn4+ ratio. It has been determined that the paramagnetic to ferromagnetic transition temperature (Curie temperature, TC) of the La0.8Ag0.2Mn0.9Co0.1O3 (LAMO-Co) is quite lower than the LAMO.

Structure, magnetism and magnetocaloric properties in performance GdClWO4 compound

Rare earth elements possessing a diverse range of optical, electrical, and magnetic properties has attracted more attention. In the present work, GdClWO4 compound with monoclinic structure was prepared, the structure, magnetism and magnetocaloric effect (MCE) were investigated. The magnetic phase transition temperature (TN), magnetic ground state and maximum magnetic entropy change (−ΔSMmax) were derived from magnetization measurements. Both first principles calculation and experimental results suggest that the compound displays antiferromagnetic (AFM) interactions, with a magnetic transition occurring at 0.6 K, shifting from a paramagnetic (PM) state to an AFM state. The −ΔSMmax is up to 35.2 J kg−1 K−1 (205.9 mJ cm−3 K−1) for GdClWO4 at T = 1.3 K under a magnetic field change of 0–50 kOe. In particular, the volumetric magnetic entropy change still remains 83.1 mJ cm−3 K−1 at 0.5 K and μ0ΔH = 20 kOe, which is almost twice as much as that of commercial refrigerant Gd3Ga5O12 (GGG) under μ0ΔH = 20 kOe, establishing GdClWO4 compound as a potential candidate for cryogenic refrigeration applications.

Structural and magnetic properties of Gd4Ga2O9 oxide with a large cryogenic magnetocaloric effect

The magnetocaloric effect has been extensively investigated in various types of magnetic solids to not only develop practical magnetic cooling applications but also deepen the understanding of these materials’ underlying inherent properties. Through experimental determination and theoretical calculation, we conducted a systematic investigation of Gd4Ga2O9 oxide in terms of its structural, magnetic, and magnetocaloric properties and found it to crystallize in a monoclinic structure belonging to the space group P21/c and to possess an antiferromagnetic semiconducting ground state. The consistent elements were uniformly distributed up to the nanoscale and presented as Gd3+, Ga3+, and O2 states, respectively. The magnetocaloric performances of Gd4Ga2O9 oxide were checked according to the parameters of maximum magnetic entropy change, refrigerant capacity, and temperature-averaged entropy changes (lift of 5 K), which were determined to be 25.77 J/kgK, 218.27 J/kg, and 23.43 J/kgK under 0–7 T magnetic field change. These parameters of Gd4Ga2O9 oxide are comparable to those of some recently reported materials with prominent performances, which means that it can be considered for cryogenic magnetic cooling applications.

Role of Griffiths phase on magnetocaloric properties and critical behavior of half-doped manganites [La0.5Sr0.5-xCaxMnO3(x = 0, 0.25, 0.5)

In this article, a comprehensive study of the effect of calcium substitution on structural magnetic, magnetocaloric properties, and role of Griffiths phase on magnetocaloric properties of half-doped manganites La0.5Sr0.5-xCaxMnO3(x=0,0.25,0.5)] have been presented. A structural phase transition I4/mcm - Pbnm is observed in the whole series. The system exhibits two magnetic transitions for Ca-00 and Ca-25, whereas only one phase transition is observed for Ca-50. Paramagnetic (PM)-ferromagnetic (FM) transition is observed in the whole series and ferromagnetic (FM) - antiferromagnetic (AFM) phase transition is only observed in Ca-25. Interestingly, short range FM clusters exist in the PM matrix of Ca-50, which is a signature of Griffiths phase (GP). The confirmation of GP has been carried out by performing iso-field magnetization measurements at 200 Oe, 500 Oe, and 1 kOe, respectively. Further magnetocaloric properties have been discussed on the basis of isothermal magnetization curves recorded at certain temperature intervals. Calcium substitution favors the enhancement of magnetic entropy change in the series, especially for Ca-50, a magnetic entropy change of 4.5J/(kgK) with relative cooling power of 180J/kg under 5T magnetic field was observed. Iso-field magnetization and magnetocaloric effect along with critical behavior analysis have been carried out to probe the GP and other inhomogeneities present in the respective series.

Revealing contrary contributions of the magnetic and lattice entropy to the inverse magnetocaloric effect in magnetic shape memory alloy

In this work, we studied the nature and dilemma of the inverse magnetocaloric effect using Ni50Mn36In14 magnetic shape memory alloy. In this context, the inverse magnetocaloric effects of Ni50Mn36In14 magnetic shape memory alloy polycrystalline samples were investigated as a function of annealing heat treatments by the thermo-magnetometry method. Two forms of Ni49TiMn36In14 magnetic shape memory alloy were studied: one that predominantly undergoes a magnetic phase transition and the other that exhibits both a magnetic and martensitic phase transition. The magnetic behaviors and magnetocaloric properties of these alloys were analyzed to investigate the competition between magnetic and lattice contributions to the total entropy change. Finally, the mutually contradictory role of magnetic and lattice contributions was demonstrated.

Magnetic and Magnetocaloric Properties of C56 like-Fullerene Structure: A Monte Carlo Study

We explored the magnetic and magnetocaloric properties of the C56 Fullerene-like system formed by the mixed spins 2 and 3/2. We applied Monte Carlo simulations using the Metropolis algorithm and show the effects of different physical parameters. We also established the ground state phase diagrams, at zero reduced temperature, in different planes formed by the reduced external magnetic field, the reduced coupling interaction between the mixed spins, and the reduced crystal field. We found that the total magnetizations predict a specific reduced critical temperature value, confirmed by the peaks observed in the magnetic susceptibilities. To elucidate the behavior of the magnetic entropy changes -ΔSm, of the C56 system, for several external magnetic field values we show that the reduced critical temperature value tC increases when increasing the reduced external magnetic field. In addition, we show the dependency of the maximum “magnetic entropy change” as a function of the reduced external magnetic field. We found an almost linear increase for this parameter when increasing the reduced external magnetic field values. The obtained hysteresis cycles of the studied system showed a decreasing effect of the reduced crystal field followed by a decrease of the magnetic hysteresis surface cycles, as well as the corresponding reduced coercive magnetic field values.

The effects of high-pressure annealing on magnetostructural transitions and magnetoresponsive properties in stoichiometric MnCoGe

In this study, phase transitions (structural and magnetic) and associated magnetocaloric properties of stoichiometric MnCoGe have been investigated as a function of annealing pressure. Metastable phases were generated by annealing at 800 °C followed by rapid cooling under pressures up to 6.0 GPa. The x-ray diffraction results reveal that the crystal cell volume of the metastable phases continuously decreases with increasing thermal processing pressure, leading to a decrease in the structural transition temperature. The magnetic and structural transitions merge and form a first-order magnetostructural transition between the ferromagnetic orthorhombic and paramagnetic hexagonal phases over a broad temperature range (>80 K) spanning room temperature, yielding considerable magnetic entropy changes. These findings demonstrate the utility of thermal processing under high pressure, i.e., high-pressure annealing, to control the magnetostructural transitions and associated magnetocaloric properties of MnCoGe without altering its chemical composition.

Structural, magnetic and magnetocaloric properties of the Er2BaCu1-xNixO5 oxides

The solid-state magnetic cooling based on the magnetocaloric (MC) effects was recognized as one of the most prospective alternative cooling methods to the gas compression technology. Exploring suitable candidate materials with prominent MC performances remains an urgent research priority in this field. Thus, we herein investigated fabricated the Er2BaCu1-xNixO5 oxides (x = 1/3, 1/2, and 2/3) and experimentally determined their structural and magnetic properties together with their MC performances. All the present studied Er2BaCu1-xNixO5 oxides are crystallized in the RE-211 type oxide structure (space group: Pnma). Considerable reversible low-temperature MC effects and good MC performances have been observed in present studied Er2BaCu1-xNixO5 oxides which were assessed by determination the parameters including the magnetic entropy changes, temperature-averaged entropy changes, and relative cooling power.

STRUCTURAL, MAGNETIC AND MAGNETOCALORIC PROPERTIES OF La0.7Sr0.2Ba0.1MnO3 MANGANITE

In this present work, the structural, magnetocaloric and magnetic properties of La0.7Sr0.2Ba0.1MnO3 (LSBM) manganite were investigated. The material was synthesized using the sol-gel method and X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) devices were used to analyze structural properties such as crystal structure and surface morphology. XRD measurement revealed that the crystal structure of LSBM manganite is hexagonal. Based on the magnetic measurements, the TC value of La0.7Sr0.2Ba0.1MnO3 manganite compounds was calculated as 362 K. The ∆SM value of sample is established as 2.79 Jkg-1K-1 in an applied magnetic field of 5T. Arrott curves revealed that the phase transition was second order.

Structure, magnetic and magnetocaloric properties of the Mn5Ge3 thin film grown on Si(111)

Structure, magnetic and magnetocaloric properties of the Mn5Ge3 thin film grown on Si(111)

Microstructure, first-order magnetostructural transition, magnetocaloric properties and exchange bias effect in Ni45−xBixMn44Sn11 alloys

Microstructure, first-order magnetostructural transition, magnetocaloric properties and exchange bias effect in Ni45−xBixMn44Sn11 alloys

Implementation of Backpropagation Neural Network for Prediction Magnetocaloric Effect of Manganite

In the field of magnetic cooling technology, there is still much to learn about the magnetocaloric properties of magnetic cooling materials. Research into magnetocaloric manganites exhibiting a significant maximum magnetic entropy change in the vicinity of ambient temperature yields encouraging outcomes for the advancement of magnetic refrigeration apparatus. Through a combination of chemical substitutions, changes in the amount of oxygen present, and different synthesis techniques, these manganites undergo lattice distortions that result in pseudocubic, orthorhombic, and rhombohedral structures instead of perovskite cubic structures. The present investigation used backpropagation neural networks (BPNNs) to investigate the correlations among maximum magnetic entropy change (MMEC), Curie temperature (Tc), lanthanum manganite compositions, lattice properties, and dopant ionic radii. Simbrain 3.07 was used to execute the BPNN model, and the suggested model accuracy was examined using coefficient determination. As a result, the model's predicted values for the mean absolute error, root mean square, and coefficient correlation for MMEC are 0.012, 0.022, and 0.9861, respectively. The model predicts that the Curie temperature mean absolute error, root mean square, and coefficient correlation will be 0.015, 0.021, and 0.9947, respectively. Based on these results, BPNN has the potential to be applied in predicting the MMEC and Tc of manganite as preliminary decision during experiments.

Control of interfacial reaction and defect formation in Gd/Bi2Te2.7Se0.3 composites with excellent thermoelectric and magnetocaloric properties

Abstract The method to combine thermoelectric (TE) and magnetocaloric (MC) cooling techniques lies in developing a new material that simultaneously possesses a large TE and good MC cooling performance. In this work, using n-type Bi2Te2.7Se0.3 (BTS) as the TE base material and Gd as the second-phase MC material, Gd/BTS composites were prepared by the spark plasma sintering method. In the composites, interfacial reaction between Gd and BTS was identified, resulting in the formation of GdTe, which has a large impact on the electron concentration through the adjustment of defect concentration. The MC/TE composite containing 2.5 wt% Gd exhibited a ZT value of 0.6 at 300 K, essentially retaining the original TE performance, while all the composites largely maintained the excellent MC performance of Gd. This work provides a potential pathway to achieving high performance in MC/TE composites.

Effect of Hydrogenation on the Magnetic and Magnetocaloric Properties of Rare Earth Intermetallic Compounds Tb0.33Ho0.33Er0.33Ni and Dy0.33Ho0.33Er0.33Ni

Effect of Hydrogenation on the Magnetic and Magnetocaloric Properties of Rare Earth Intermetallic Compounds Tb0.33Ho0.33Er0.33Ni and Dy0.33Ho0.33Er0.33Ni

Elastic, electronic, magnetic and magnetocaloric properties of janus MnXO (X=S, Se and Te) monolayers: First-principles and Monte Carlo investigations

In this work, we present the first theoretical analysis of the elastic, electronic, magnetic and magnetocaloric properties of 1T-phase Janus MnXO (X = S, Se and Te) monolayers using first-principle calculations based on density functional theory combined with Monte Carlo simulation. The stability of the studied monolayers has been analyzed by using the elastic constants Cij and formation energy, which indicate that all monolayers are stable. Moreover, the electronic properties reveal the metal characteristics of all monolayers, with a total magnetic moment of 3.25 μB, 3.81 μB and 4.09 μB for MnSO, MnSeO, and MnTeO, respectively. Further, the extracted critical temperature values (Tc) from Monte Carlo simulation are Tc = 115 K, Tc = 130 K and Tc = 82 K, for MnSO, MnSeO and MnTeO, respectively. Interestingly, the predicted maximum magnetic entropy change −ΔSmax and maximum relative cooling power RCP (and adiabatic temperature change) are 10,38 J/kg.K and 763,43 J/kg (7,11 K) for MnSO, 6,79 J/kg.K and 515,57 J/kg (3,25K) for MnSeO, and 6,39 J/kg.K and 407,16 J/kg (3,46 K) for MnTeO at a magnetic field of 5T. These results suggest that the Janus MnXO (X = S, Se and Te) monolayers are a potential materials for use in magnetic nanodevices and low-dimensional magnetic refrigeration.

Exploring magnetocaloric effect of coordination polymer based on Mn(II) and Nb(IV) by relaxation calorimetry

Magnetocaloric properties of {MnII2(imH)2(H2O)4 [NbIV(CN)8]·4H2O}n molecular magnet are reported. The coordination polymer crystallizes in the monoclinic P21/c space group and displays a magnetic second-order phase transition at Tc ≈ 24.1 K. The relaxation calorimetry measurements are analyzed in order to determine the temperature dependence of the magnetic entropy change ΔSM as well as the adiabatic temperature change ΔTad for an array of applied field changes ranging from 0 to 9 T. For μ0ΔH = 5 T the entropy change ΔSM attains the maximum value of 6.55 J K−1 mol−1 (9.5 J K−1 kg−1) at 25.5 K, while the corresponding maximum value of ΔTad amounts to 2.02 K at 25.1 K. The critical behavior of the isothermal entropy change is discussed. In particular, the analysis of the field dependence of ΔSM in terms of the power law implies that the studied compound belongs to the mean-field universality class.

A cryogenic magnetic refrigerant: Magnetocaloric study of EuB2O4 compound

Adiabatic demagnetization refrigeration (ADR) technology has the advantage of not relying on helium-3 resources and gravity compared to traditional ultra-low temperature refrigeration technology. The key to the development of ADR technology is finding magnetic refrigeration materials with brilliant magnetocaloric properties. In this study, polycrystalline EuB2O4 was successfully prepared by solid-phase reaction method. The analysis of magnetic susceptibility curves and first-principles calculations reveals a magnetic phase transition from antiferromagnetic (AFM) to paramagnetic (PM) of EuB2O4, with TN = 0.72 K. The magnetic entropy change (-ΔSM) is evaluated up to 5 T, with the maximum value of 19.4 J·kg−1K−1 (88.7 mJ·cm−3K−1), 35.0 J·kg−1K−1 (160.0 mJ·cm−3K−1) and 50.8 J·kg−1K−1 (232.2 mJ·cm−3K−1) at around T = 1.3 K and under μ0ΔH = 1 T, 2 T and 5 T, respectively, which were significantly higher than those of the commercial magnetic refrigerant Gd3Ga5O12. The large -ΔSM suggest that EuB2O4 is a potentially great magnetic refrigerant for obtaining ultra-low temperature.