Journal articles: 'Magnetocaloric effect, phase transition, magnetic refrigeration'

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Albertini, Franca, Massimo Solzi, Antonio Paoluzi, and Lara Righi. "Magnetocaloric Properties and Magnetic Anisotropy by Tailoring Phase Transitions in NiMnGa Alloys." Materials Science Forum 583 (May 2008): 169–96. http://dx.doi.org/10.4028/www.scientific.net/msf.583.169.

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The giant magnetocaloric properties of NiMnGa alloys can be enhanced by suitable composition changes that make structural and magnetic transition temperatures to coincide. In this paper we report results on critical temperatures, magnetic anisotropy, and magnetocaloric effect in Ni- and Mn-rich alloys as a function of composition. A phenomenological phase diagram, useful for the identification by thermomagnetic analysis of magnetic and structural transitions in the vicinity of their coincidence, is proposed. Particular emphasis is given to the discussion of giant magnetocaloric effect of those alloys showing a first order magnetostructural transition, the method of its determination, and the potentialities for applications in the field of magnetic refrigeration.

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Wang, Gao Feng, Zeng Ru Zhao, Xiao Bin Zhang, and Xue Feng Zhang. "First-Order Phase Transition and Magnetocaloric Effect of MnFeP_0.63Ge_0.12Si_0.25 Compound." Advanced Materials Research 1053 (October 2014): 37–40. http://dx.doi.org/10.4028/www.scientific.net/amr.1053.37.

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In this paper, the magnetic phase transition and magnetocaloric effect have been investigated in the Fe2P-type MnFeP0.63Ge0.12Si0.25compound. The X-ray diffraction patterns measured at different temperatures indicate that the crystal structure remains and the lattice parameters change sharply near the transition temperature when a phase transition takes place. The isofield magnetization curves on heating and cooling and the Arrott plots reveal that the nature of the transition is first order. The characteristic of giant magnetocaloric effect results from the field-induced first-order metamagnetic phase transition, which makes the compound having potential applications in magnetic refrigeration.

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Liu, Quanyi, Zhaojun Mo, Huicai Xie, Qi Fu, Jun Shen, and Jinliang Zhao. "Magnetic properties and cryogenic magnetocaloric effect in monoclinic RE_8.66(BO₃)₂(B₂O₅)O₈ (RE = Er, Tm) compounds." Journal of Applied Physics 133, no. 1 (January 7, 2023): 013902. http://dx.doi.org/10.1063/5.0129082.

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Researchers in cryogenic magnetic refrigeration have never stopped pursuing magnetic refrigerants with lower ordering temperatures and larger magnetocaloric effects. Rare earth borates have been found to be potential cryogenic magnetocaloric materials due to their low phase transition temperatures and considerable magnetic entropy changes. Here, two rare earth borates RE8.66(BO3)2(B2O5)O8 ( RE = Er, Tm) were successfully fabricated, and the crystallographic and magnetic parameters as well as cryogenic magnetocaloric effects were systematically evaluated. The compounds are deemed to crystalize in a monoclinic structure belonging to space group C2/m. They are both second-order phase transition materials without any long-range order above 2 K. These monoclinic rare earth borates, especially for Er8.66(BO3)2(B2O5)O8, show more considerable low-field magnetocaloric effects than rare earth orthoborates. For Δ H = 1 and 2 T, the values of −Δ[Formula: see text] are 5.1 and 11.2 J/(kg K) for Er8.66(BO3)2(B2O5)O8, 3.0 and 5.3 J/(kg K) for Tm8.66(BO3)2(B2O5)O8, respectively. Therefore, they are regarded as potential candidates for cryogenic magnetic refrigeration.

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Gao, Li, Ying Feng, Shaohui Hu, and Xiangyang Xin. "Magnetostructural Transition and Magnetocaloric Effect with Negligible Magnetic Hysteresis in MnCoGe1.02−xGax Alloys." Metals 12, no. 7 (July 5, 2022): 1143. http://dx.doi.org/10.3390/met12071143.

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The behavior of magnetostructural transition and the magnetocaloric effect in the MnCoGe1.02−xGax (x = 0, 0.02, 0.04, 0.06) alloys are investigated in this study. The addition of Ga changes the crystal structure of MnCoGe1.02−xGax alloys at room temperature and reduces the phase transition temperatures with increasing Ga content. The coupling of magnetostructural transition and negligible magnetic hysteresis is observed in the Mn-Co-Ge-Ga alloy. At 305 K, under the action of a 5 T magnetic field, the MnCoGeGa0.02 alloy exhibits 23.47 J/kg∙K magnetic entropy change, and its refrigeration capacity reaches 387 J/kg. The large magnetic entropy change near room temperature and the high refrigeration capacity in the Mn-Co-Ge-Ga alloy make it a promising new type of refrigeration material.

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Pecharsky, Vitalij K., Jun Cui, and Duane D. Johnson. "(Magneto)caloric refrigeration: is there light at the end of the tunnel?" Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 374, no. 2074 (August 13, 2016): 20150305. http://dx.doi.org/10.1098/rsta.2015.0305.

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Caloric cooling and heat pumping rely on reversible thermal effects triggered in solids by magnetic, electric or stress fields. In the recent past, there have been several successful demonstrations of using first-order phase transition materials in laboratory cooling devices based on both the giant magnetocaloric and elastocaloric effects. All such materials exhibit non-equilibrium behaviours when driven through phase transformations by corresponding fields. Common wisdom is that non-equilibrium states should be avoided; yet, as we show using a model material exhibiting a giant magnetocaloric effect, non-equilibrium phase-separated states offer a unique opportunity to achieve uncommonly large caloric effects by very small perturbations of the driving field(s). This article is part of the themed issue ‘Taking the temperature of phase transitions in cool materials’.

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Мирошкина, О. Н., В. В. Соколовский, М. А. Загребин, С. В. Таскаев, and В. Д. Бучельников. "Теоретический подход к исследованию магнитных и магнитокалорических свойств сплавов Гейслера Ni-Mn-Ga." Физика твердого тела 62, no. 5 (2020): 697. http://dx.doi.org/10.21883/ftt.2020.05.49232.22m.

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The study of the magnetic and magnetocaloric properties of Ni2+xMn1-xGa (x = 0.16, 0.18 and 0.3) Heusler alloys are presented. The research was performed using a model based on the Malygin theory of smeared phase transitions, Bean–Rodbell theory of first-order phase transitions, and mean-field theory. The temperature dependences of deformation, magnetization, and isothermal entropy change are studied. It is shown that the largest change in magnetic entropy is observed in the Ni2.18Mn0.82Ga alloy, in which the martensitic transition is accompanied by a change in magnetic ordering. The smallest change in entropy is demonstrated by the Ni2.3Mn0.7Ga alloy, in which magnetocaloric the effect is observed in the martensitic phase upon a change in magnetic ordering. However, the refrigeration capacity of this alloy is twice as much as for the other considered compositions.

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Song, Zhao, Zongbin Li, Bo Yang, Haile Yan, Claude Esling, Xiang Zhao, and Liang Zuo. "Large Low-Field Reversible Magnetocaloric Effect in Itinerant-Electron Hf1−xTaxFe2 Alloys." Materials 14, no. 18 (September 11, 2021): 5233. http://dx.doi.org/10.3390/ma14185233.

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First-order isostructural magnetoelastic transition with large magnetization difference and controllable thermal hysteresis are highly desirable in the development of high-performance magnetocaloric materials used for energy-efficient and environmental-friendly magnetic refrigeration. Here, we demonstrate large magnetocaloric effect covering the temperature range from 325 K to 245 K in Laves phase Hf1−xTaxFe2 (x = 0.13, 0.14, 0.15, 0.16) alloys undergoing the magnetoelastic transition from antiferromagnetic (AFM) state to ferromagnetic (FM) state on decreasing the temperature. It is shown that with the increase of Ta content, the nature of AFM to FM transition is gradually changed from second-order to first-order. Based on the direct measurements, large reversible adiabatic temperature change (ΔTad) values of 2.7 K and 3.4 K have been achieved under a low magnetic field change of 1.5 T in the Hf0.85Ta0.15Fe2 and Hf0.84Ta0.16Fe2 alloys with the first-order magnetoelastic transition, respectively. Such remarkable magnetocaloric response is attributed to the rather low thermal hysteresis upon the transition as these two alloys are close to intermediate composition point of second-order transition converting to first-order transition.

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Sechovský, Vladimír, Denys Vasylyev, and Jan Prokleška. "Magnetocaloric and Thermal Properties of Ho(Co1–xSix)2 Compounds." Zeitschrift für Naturforschung B 62, no. 7 (July 1, 2007): 965–70. http://dx.doi.org/10.1515/znb-2007-0714.

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Abstract The specific heat and thermal conductivity of HoCo2 and Ho(Co0.95Si0.05)2 were measured as functions of temperature in several constant magnetic fields up to 8 T. From a specific-heat data analysis the isothermal entropy change and the magnetocaloric effect (MCE) have been evaluated in a wide temperature range for several values of the applied magnetic field. The considerable values of the magnetocaloric effect in the vicinity of the magnetic ordering transition are qualifying both compounds as suitable for magnetic refrigeration purposes. The magnetic phase transition temperature (TC) increases from 77 K for HoCo2 to 103 K for Ho(Co0.95Si0.05)2 while the large MCE in the vicinity of TC is maintained, which demonstrates ways of tuning the operating temperatures of the magnetic refrigerant.

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Jing, Chao, X. L. Wang, D. H. Yu, Y. J. Yang, B. J. Kang, S. X. Cao, J. C. Zhang, Z. Li, J. Zhu, and B. Lu. "Magnetic Phase Transitions and Magnetocaloric Properties of Gd₅Si_0.4In_3.6 Compound." Applied Mechanics and Materials 320 (May 2013): 67–71. http://dx.doi.org/10.4028/www.scientific.net/amm.320.67.

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The magnetic phase transitions and magnetocaloric properties of Gd5Si0.4In3.6 compound have been investigated. Magnetothermal measurements performed at different conditions reveal that the sample undergoes two magnetic phase transitions. One is a second-order transition from paramagnetic to ferromagnetic state at about 197 K, the other is a first-order transition when the temperature is reduced to 75 K. The magnetocaloric effect around Curie temperature (TC) was calculated in terms of isothermal magnetic entropy change by using Maxwells equation,which remains over a quite wide temperature span of 70 K between the temperature region from160 to 240 K, and thus makes this material attractive for magnetic refrigerator applications.

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Qiao, Kaiming, Yuhang Liang, Shulan Zuo, Cheng Zhang, Ziyuan Yu, Yi Long, Fengxia Hu, Baogen Shen, and Hu Zhang. "Regulation of Magnetocaloric Effect in Ni40Co10Mn40Sn10 Alloys by Using a Homemade Uniaxial Strain Pressure Cell." Materials 15, no. 12 (June 18, 2022): 4331. http://dx.doi.org/10.3390/ma15124331.

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In this study, a homemade uniaxial strain pressure cell was designed to be directly used in the standard magnetometers whereby the magnetic properties of samples subjected to a uniaxial strain and magnetic field were characterized. Its feasibility has been demonstrated by the uniaxial strain control of the phase transition and magnetocaloric effect in Ni40Co10Mn40Sn10 (NCMS) alloys. With the assistance of a uniaxial strain of ~0.5%, the cooling temperature span of NCMS alloys is broadened by 2 K, and the refrigeration capacity under a 3 T magnetic field change increases from 246 to 277 J/kg. This research provides not only direct experimental assistance for the tuning of phase transition by the uniaxial strain but also possibilities for studying the coupled caloric effect in first-order phase transition materials under a combined uniaxial strain and magnetic field by the thermodynamic analysis.

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Ahmed, E. M., H. R. Alamri, S. M. Elghnam, O. Eldarawi, T. E. Tawfik, A. M. Mahmoud, S. E. Elwan, O. M. Hemeda, M. A. Hamad, and G. A. Hussein. "Tuning Magnetocaloric Properties for La-=SUB=-1-x-=/SUB=-Sr-=SUB=-x-=/SUB=-CoO-=SUB=-3-=/SUB=-." Физика твердого тела 63, no. 10 (2021): 1551. http://dx.doi.org/10.21883/ftt.2021.10.51478.pss162.

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Low magnetic field magnetocaloric (MC) properties of La1-xSrxCoO3 (x=0.3 and 0.5) near phase transition from a ferromagnetic to a paramagnetic state were investigated. It is shown that the change of Sr content allows MC effect in La1-xSrxCoO3 to be tunable, which is more practical for construction of MC refrigeration. MC properties of the x=0.5 sample are significantly greater than that of the x=0.3 one. Furthermore, the results show that MC properties of La1-xSrxCoO3 samples are significantly larger, and comparable with some MC properties of many materials like Gd1-xCaxBaCo2O5.5 and Ge0.95Mn0.05. Keywords: magnetocaloric effect, La1-xSrxCoO3, magnetic entropy change.

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Pal, S., and A. Basu. "Investigation of Magnetocaloric Effect in a New Perovskite Oxide La-=SUB=-0.7-x-=/SUB=-Ho-=SUB=-x-=/SUB=-Sr-=SUB=-0.3-=/SUB=-MnO-=SUB=-3-=/SUB=- (x=0.2 and 0.3)." Физика твердого тела 65, no. 2 (2023): 295. http://dx.doi.org/10.21883/ftt.2023.02.54304.41.

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The magnetocaloric effect (MCE) of La0.7-xHoxSr0.3MnO3 (x=0.2 and 0.3) perovskite oxides has been investigated. A phenomenological model is adopted for simulation of magnetization variation with temperature to investigate magnetocaloric properties such as magnetic entropy change, heat capacity change and relative cooling power. The results indicate the potential of this series of materials to achieve the MCE at temperatures near Curie temperature (TC). These compounds present as prospective candidates for cooling system in a wide temperature interval in the vicinity of room temperature. The results confirm that the phenomenological model is undoubtedly beneficial for the prediction of the magnetocaloric effect of magnetic materials. Moreover, the effect of holmium (Ho) doping in MCE of La0.7Sr0.3MnO3 has been discussed comparing the results obtained from our calculation for Ho-doped La0.7Sr0.3MnO3 and for non-doped La0.7Sr0.3MnO3 calculated earlier. Keywords: solid state magnetic refrigeration, phase transition, phenomenological model.

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13

Guan, Ziqi, Jing Bai, Yu Zhang, Jianglong Gu, Xinzeng Liang, Yudong Zhang, Claude Esling, Xiang Zhao, and Liang Zuo. "Simultaneously realized large low-temperature magnetocaloric effect and good mechanical properties in Ni₃₆Co₁₃Mn₃₅Ti₁₆ alloy." Journal of Applied Physics 131, no. 16 (April 28, 2022): 165107. http://dx.doi.org/10.1063/5.0088692.

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In this work, we present the observation of large low-temperature magnetocaloric effect and good mechanical properties in the Ni36Co13Mn35Ti16 alloy. The phase transition behaviors, magnetocaloric effect, and mechanical properties for the Ni36Co13Mn35Ti16 non-textured polycrystalline alloy were systematically investigated. Under the magnetic field changes of 5 T, a typical meta-magnetic behavior with a large magnetization change of about 110 A m2 kg−1 between the austenite and martensite can be observed, the maximum magnetic entropy changes (ΔS m) of the Ni36Co13Mn35Ti16 alloy is ∼16.1 J kg−1 K−1 at 148 K. Furthermore, the maximum compressive stress and strain are 894 MPa and 8.0%, respectively. The scanning electron microscope and first-principles calculations were used to analyze the fracture mechanism and the bonding interaction. In the combination of the large low-temperature magnetocaloric effect and good mechanical properties, the Ni36Co13Mn35Ti16 alloy has a good prospect for low-temperature magnetic refrigeration applications.

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Dan, Nguyen Huy, and Nguyen Manh An. "Magnetic Properties and Giant Magnetocaloric Effect In Mn-based Heusler Compounds." Communications in Physics 23, no. 2 (June 10, 2013): 139. http://dx.doi.org/10.15625/0868-3166/23/2/2863.

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Magnetic properties and giant magnetocaloric effect (GMCE) of Mn-based Heusler compounds such as Co-Mn-Si, Ni-Mn-Sn, Ni-Mn-Sb have been investigated. The results show that the structure strongly influences on magnetic properties and GMCE of these alloys. The coexistence of ferromagnetic (FM) and antiferromagnetic (AFM) orders is observed. The magnetic phase transitions can be controlled by changing composition and annealing condition of the alloys. GMCEs with large magnitude and wide working temperature range have been obtained on these alloys showing their application potential for magnetic refrigeration technology.

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Hà, Nguyen Hoang. "MAGNETIC PROPERTIES AND MAGNETOCALORIC EFFECT OF Fe90-xPrxZr10 RAPIDLY QUENCHED ALLOYS." Vietnam Journal of Science and Technology 56, no. 1A (May 4, 2018): 59. http://dx.doi.org/10.15625/2525-2518/56/1a/12504.

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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.

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Guo, Zhen Gang, and Hong Mei Qiu. "Magnetocaloric Effect of Ni₄₄Co₆Mn₄₀Cu_xSn_10-x Quinary Alloy Comes from the Martensitic Transformation." Key Engineering Materials 787 (November 2018): 17–24. http://dx.doi.org/10.4028/www.scientific.net/kem.787.17.

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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.

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Atanasov, Roman, Rares Bortnic, Razvan Hirian, Eniko Covaci, Tiberiu Frentiu, Florin Popa, and Iosif Grigore Deac. "Magnetic and Magnetocaloric Properties of Nano- and Polycrystalline Manganites La(0.7−x)EuxBa0.3MnO3." Materials 15, no. 21 (October 31, 2022): 7645. http://dx.doi.org/10.3390/ma15217645.

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Here, we report synthesis and investigations of bulk and nano-sized La(0.7−x)EuxBa0.3MnO3 (x ≤ 0.4) compounds. The study presents a comparison between the structural and magnetic properties of the nano- and polycrystalline manganites La(0.7−x)EuxBa0.3MnO3, which are potential magnetocaloric materials to be used in domestic magnetic refrigeration close to room temperature. The parent compound, La0.7Ba0.3MnO3, has Curie temperature TC = 340 K. The magnetocaloric effect is at its maximum around TC. To reduce this temperature below 300 K, we partially replaced the La ions with Eu ions. A solid-state reaction was used to prepare bulk polycrystalline materials, and a sol-gel method was used for the nanoparticles. X-ray diffraction was used for the structural characterization of the compounds. Transmission electron spectroscopy (TEM) evidenced nanoparticle sizes in the range of 40–80 nm. Iodometry and inductively coupled plasma optical emission spectrometry (ICP-OES) was used to investigate the oxygen content of the studied compounds. Critical exponents were calculated for all samples, with bulk samples being governed by tricritical mean field model and nanocrystalline samples governed by the 3D Heisenberg model. The bulk sample with x = 0.05 shows room temperature phase transition TC = 297 K, which decreases with increasing x for the other samples. All nano-sized compounds show lower TC values compared to the same bulk samples. The magnetocaloric effect in bulk samples revealed a greater magnetic entropy change in a relatively narrow temperature range, while nanoparticles show lower values, but in a temperature range several times larger. The relative cooling power for bulk and nano-sized samples exhibit approximately equal values for the same substitution level, and this fact can substantially contribute to applications in magnetic refrigeration near room temperature. By combining the magnetic properties of the nano- and polycrystalline manganites, better magnetocaloric materials can be obtained.

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Ma, Lei, Liang Zhou, Lin Li, Zheng Fei Gu, and Gang Cheng. "Structure and Inverse Magnetocaloric Effect of Mn_1.2Co_0.8Si_0.2P_0.8 Compound Prepared by SPS." Materials Science Forum 849 (March 2016): 860–64. http://dx.doi.org/10.4028/www.scientific.net/msf.849.860.

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The single-phase Mn1.2Co0.8Si0.2P0.8 compound was fabricated by the spark plasma sintering (SPS) technology followed by vacuum annealing. The microstructure, Néel temperature (TN) and “inverse” magnetocaloric effect of this compound were investigated. The results show that the structure of Mn1.2Co0.8Si0.2P0.8 compound prepared by SPS is a single phase with precise stoichiometric proportion. Increasing the magnetic field from 0.05 T to 1 T, the TN of the material reduces gradually from 110 k to 45 k, and a splitting of TN appears. The splitting of the antiferro-to-ferromagnetic transition is an intrinsic feature rather than the secondary phase. Though the maxima entropy changes is about 0.6 Jkg-1K-1 at B=5T, the Mn1.2Co0.8Si0.2P0.8 phase synthesized by SPS is more favorable, more overall magnetic moment. In addition to the magnetic refrigeration applications, this compound may be used in thermomagnetic generators.

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Fang, Yue, Yu Ting Dai, Zhi Shuai Xu, and Hong Xing Zheng. "Phase Transition Behavior and Magnetocaloric Effect in a Heusler Ni₅₀Mn₃₇Sn₁₃ Unidirectional Crystal." Materials Science Forum 913 (February 2018): 759–64. http://dx.doi.org/10.4028/www.scientific.net/msf.913.759.

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A unidireon heating, followed with a ferromagnetic- paramagnetic transition in austenite for the produced unidirectional crystal. Under a magnetic field change of 3 T, the total effective refrigeration capacity was strikingly enhanced up to 125 J/kg, nearly 64% higher than that of polycrystalline master alloy ctional crystal of Heusler Ni50Mn37Sn13 material was produced using a modified high-pressure optical zone-melting furnace. A structural transformation between weak-magnetization martensite and ferromagnetic austenite occurred first up(76 J/kg). The modified high-pressure optical zone-melting technique demonstrated high potentials for the fabrication of super-performance Heusler Ni-Mn-based magnetocaloric materials.

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Jin, Pingxia, Yuqiang Li, Yuting Dai, Zhishuai Xu, Changjiang Song, Zhiping Luo, Qijie Zhai, Ke Han, and Hongxing Zheng. "Zn and P Alloying Effect in Sub-Rapidly Solidified LaFe11.6Si1.4 Magnetocaloric Plates." Metals 9, no. 4 (April 11, 2019): 432. http://dx.doi.org/10.3390/met9040432.

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The occupation mechanism and magnetic transition behavior of trace Zn and P alloying in the sub-rapidly solidified LaFe11.6Si1.4 magnetocaloric plates were investigated. The LaFe11.6Si1.4, LaFe11.6Si1.4Zn0.03, and LaFe11.6Si1.4P0.03 plates were fabricated using the centrifugal casting method in the present work. Experimental results showed that both Zn and P elements were distributed in the La5Si3 and LaFeSi phases during sub-rapid solidification. After annealed at 1373 K for 72 h, the LaFe11.6Si1.4 plate underwent a second-order magnetic transition, while both the LaFe11.6Si1.4Zn0.03 and LaFe11.6Si1.4P0.03 plates underwent a first-order transition. In combination with X-ray diffraction results, it was proposed that both Zn and P atoms prefer to enter the 96i site substituting for FeII/Si atoms according to the density-functional reconstruction of crystallographic structure. The Zn addition led to a slight decrease in magnetic entropy change from 7.0 to 5.9 J/(kg⋅K), while the P addition strikingly enhanced this property to 31.4 J/(kg⋅K) under a magnetic field change of 3 T. The effective refrigeration capacity of the annealed LaFe11.6Si1.4P0.03 plate reached 189.9 J/kg.

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Hussain, Imad, S. N. Khan, Tentu Nageswara Rao, Riyaz Uddin, Jong Woo Kim, and Bon Heun Koo. "Tailoring the Magnetic Properties and Magnetocaloric Effect in Double Perovskites Sr2FeMo1–xNbxO6." Science of Advanced Materials 12, no. 3 (March 1, 2020): 391–97. http://dx.doi.org/10.1166/sam.2020.3648.

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The crystal structure, magnetic and magnetocaloric properties of the Sr2FeMo1–xNbxO6 (0 ≤ x ≤ 0.3) samples prepared by solid state reaction method were investigated using X-ray diffraction (XRD) and magnetic measurements. The room temperature XRD profiles obtained for all the samples revealed the formation of the double perovskite tetragonal structure with I4/mmm symmetry. Maximum values of spontaneous magnetization (17.6 emu/g at 150 K) and Curie temperature, TC (380 K) were observed in the Sr2FeMo0.9Nb0.1O6 sample indicating that low Niobium (Nb) substitution (x = 0.1) at the Mo site in the host material resulted in higher magnetization and TC. Lower values of magnetization and TC were recorded in the samples with higher Nb concentration (x = 0.2, 0.3) that was attributed to the decrease in orbital hybridization and increase in anti-site disorder resulting from heavy doping. A second order of the magnetic phase transition in each sample was confirmed by the magnetization measurements and Arrott plots. The maximum magnetic entropy change and relative cooling power (RCP) were enhanced in lowest Nb doped sample (x = 0.1) suggesting that this compound can be used in magnetic refrigeration technology.

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Dhungana, Surendra, Jacob Casey, Dipesh Neupane, Arjun K. Pathak, Sunil Karna, and Sanjay R. Mishra. "Effect of Metal-Oxide Phase on the Magnetic and Magnetocaloric Properties of La0.7Ca0.3MnO3-MO (MO=CuO, CoO, and NiO) Composite." Magnetochemistry 8, no. 12 (November 22, 2022): 163. http://dx.doi.org/10.3390/magnetochemistry8120163.

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The study reports the synthesis and characterization of the magnetic and magnetocaloric effects of metal-oxide (MO) modified La0.7Ca0.3MnO3 perovskites manganite. The powder composite samples, with a nominal composition of (1 − x)La0.7Ca0.3MnO3-xMO (Wt.% x = 0.0, 2.5, 5.0), were prepared using the facile autocombustion method, followed by an annealing process. The phase purity and structure were confirmed by X-ray diffraction. Temperature and field-dependent magnetization measurements and Arrott analysis revealed mixed first- and second-order phase transition (ferromagnetic to paramagnetic) in composite samples. The phase transition temperature shifted to lower temperatures with the addition of MO in the composite. A large magnetic entropy change (4.75 JKg−1K−1 at 1T and 8.77 JKg−1K−1 at 5T) was observed in the La0.7Ca0.3MnO3 (LCMO) sample and was suppressed, due to the presence of the MO phase in the composite samples. On the other hand, the addition of MO as a secondary phase in the LCMO samples enhanced their relative cooling power (RCP). The RCP of all composite samples increased with respect to the pristine LCMO, except for LCMO–5%NiO. The highest RCP value of 267 JKg−1 was observed in LCMO–5%CuO samples, which was 23.4% higher than the 213 JKg−1 observed for the pure LCMO at a magnetic field of 5T. The enhanced RCP of these composites makes them attractive for potential refrigeration applications.

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Su, Wen-Xia, Hai-Ming Lu, Zi-Rui Zeng, Yi-Fei Zhang, Jian Liu, Kun Xu, Dun-Hui Wang, and You-Wei Du. "High-throughput computation on relationship between composition and magnetic phase transition temperature of LaFe11.5Si1.5-based magnetic refrigeration materials." Acta Physica Sinica 70, no. 20 (2021): 207501. http://dx.doi.org/10.7498/aps.70.20211085.

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La(Fe, Si)13-based alloys have attracted more and more attention, for they exhibit giant magnetocaloric effects. In order to broaden their magnetic refrigeration temperatureranges, achieving a series of La(Fe, Si)13-based alloys with different magnetic phase transition temperatures is of great significance. Unlike the traditional research method, in this paper, a high-throughput first-principles computation is performed to estimate the magnetic phase transition temperature of the LaFe11.5Si1.5-based alloy by employing AMS-BAND software and the mean field theory. We investigate the effects of doping Mn, Co, Ni, Al atoms and Fe-vacancies on the magnetic phase transition temperature of LaFe11.5Si1.5-based alloy, and give the phase diagrams between the composition and magnetic phase transition temperature. The calculated results demonstrate that the magnetic phase transition temperature of the LaFe11.5Si1.5-based alloy increases with the increase of Co and Ni content. However, it shows an opposite result when Mn atom is doped. As for the LaFe11.5Si1.5-based alloy with the Fe-vacancies, the research results indicate that the absence of Fe atoms will reduce the magnetic phase transition temperature. Furthermore, when Mn, Co, Ni and Al atoms are doped in the alloys with Fe-vacancies, the variation tendency of the magnetic phase transition temperature with the change of the doping content is similar to that without the Fe-vacancies. Some estimated results are compared with the experimental or reported results, showing that they are in good agreement with each other. The PDOS and the magnetic moments of Fe atoms in the Mn, Co, Ni, Al-doped LaFe11.5Si1.5-based alloys are calculated, in which only the doping of Mn atoms can increase the magnetic moments of Fe atoms. Using the method of high-throughput first-principles calculation can effectively reduce the research cost and improve the working efficiency. In addition, it can provide technical support for the experimental selection of magnetocaloric materials with appropriate magnetic phase transition temperatures.

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Su, Wen-Xia, Hai-Ming Lu, Zi-Rui Zeng, Yi-Fei Zhang, Jian Liu, Kun Xu, Dun-Hui Wang, and You-Wei Du. "High-throughput computation on relationship between composition and magnetic phase transition temperature of LaFe11.5Si1.5-based magnetic refrigeration materials." Acta Physica Sinica 70, no. 20 (2021): 207501. http://dx.doi.org/10.7498/aps.70.20211085.

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La(Fe, Si)13-based alloys have attracted more and more attention, for they exhibit giant magnetocaloric effects. In order to broaden their magnetic refrigeration temperatureranges, achieving a series of La(Fe, Si)13-based alloys with different magnetic phase transition temperatures is of great significance. Unlike the traditional research method, in this paper, a high-throughput first-principles computation is performed to estimate the magnetic phase transition temperature of the LaFe11.5Si1.5-based alloy by employing AMS-BAND software and the mean field theory. We investigate the effects of doping Mn, Co, Ni, Al atoms and Fe-vacancies on the magnetic phase transition temperature of LaFe11.5Si1.5-based alloy, and give the phase diagrams between the composition and magnetic phase transition temperature. The calculated results demonstrate that the magnetic phase transition temperature of the LaFe11.5Si1.5-based alloy increases with the increase of Co and Ni content. However, it shows an opposite result when Mn atom is doped. As for the LaFe11.5Si1.5-based alloy with the Fe-vacancies, the research results indicate that the absence of Fe atoms will reduce the magnetic phase transition temperature. Furthermore, when Mn, Co, Ni and Al atoms are doped in the alloys with Fe-vacancies, the variation tendency of the magnetic phase transition temperature with the change of the doping content is similar to that without the Fe-vacancies. Some estimated results are compared with the experimental or reported results, showing that they are in good agreement with each other. The PDOS and the magnetic moments of Fe atoms in the Mn, Co, Ni, Al-doped LaFe11.5Si1.5-based alloys are calculated, in which only the doping of Mn atoms can increase the magnetic moments of Fe atoms. Using the method of high-throughput first-principles calculation can effectively reduce the research cost and improve the working efficiency. In addition, it can provide technical support for the experimental selection of magnetocaloric materials with appropriate magnetic phase transition temperatures.

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G, Jagadish Kumar, Ashika Jose, E. P. Jinu, T. T. Saravanan, E. Senthil Kumar, M. Navaneethan, H. Sreemoolanadhan, and K. Kamala Bharathi. "Observation of Griffiths phase, critical exponent analysis and high magnetocaloric effect near room temperature at low magnetic field in V-doped La_0.7Sr_0.3MnO₃." Journal of Physics D: Applied Physics 55, no. 21 (February 25, 2022): 215001. http://dx.doi.org/10.1088/1361-6463/ac4a99.

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Abstract We report on observation of the Griffiths phase (GP), high magnetocaloric properties at low magnetic fields and temperature-dependent critical exponents of La0.7Sr0.3V x Mn1−x O3 (x = 0, 0.05 and 0.1) perovskite bulk materials. The Curie temperature (T C) of pure La0.7Sr0.3MnO3 (LMSO) is seen to be 368.7 K and decreases toward room temperature (RT) (342.2 K) by 10 mol% V doping at the Mn site. V doping leads to an enhancement in magnetic entropy change (−ΔS M) from 1 J kg−1 K−1to 1.41 J kg−1 K−1. V doping at a Mn site leads to the formation of GP, a magnetic disorder due to the coexistence of a paramagnetic (PM) matrix and short-range ferromagnetic (FM) clusters. X-ray photoelectron spectroscopy analysis confirms the presence of mixed-valence V4+/V5+along with Mn3+/Mn4+ ions contributing to various double exchange interactions. The natures of phase transitions and magnetic interactions are analyzed by evaluating critical exponents δ, β, and γ. All the samples show second-order FM to PM phase transition, confirmed from the modified Arrott plots and critical exponent analysis carried out using the Kouvel–Fisher method. The enhancement in magnetic entropy change along with the decrease in Curie temperature toward RT by V doping in the LMSO oxides indicates the possible application of these materials in magnetic refrigeration at low magnetic fields.

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Zhao, Bojun, Xiaojie Hu, Fuxiao Dong, Yan Wang, Haiou Wang, Weishi Tan, and Dexuan Huo. "The Magnetic Properties and Magnetocaloric Effect of Pr0.7Sr0.3MnO3 Thin Film Grown on SrTiO3 Substrate." Materials 16, no. 1 (December 21, 2022): 75. http://dx.doi.org/10.3390/ma16010075.

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The magnetic behaviors and magnetocaloric effect (MCE) of Pr0.7Sr0.3MnO3 (PSMO-7) film grown on a (001) SrTiO3 single-crystal substrate by a pulsed laser deposition (PLD) were studied in this paper. X-ray diffraction with a high resolution (HRXRD) measurement shows that PSMO-7 film is grown with a (001) single orientation. The magnetic properties and the MCE related to the ferromagnetic (FM) phase transition of the PSMO-7 film are investigated using the temperature dependence of magnetization M(T) and the magnetic field dependence of magnetization M(H). The M(T) data suggest that with decreasing temperatures, the PSMO-7 film goes through the transition from the paramagnetic (PM) state to the FM state at around the Curie temperature (TC). The TC (about 193 K) can be obtained by the linear fit of the Curie law. Magnetic hysteresis loop measurements show that the PSMO-7 film exhibits the FM feature at temperatures of 10, 100, and 150 K (low magnetic hysteresis can be found), while the film reveals the PM feature with the temperature increased up to 200 and/or 300 K. The research results of M(H) data are consistent with the M(T) data. Furthermore, the magnetic entropy change () of the PSMO-7 film was studied. It was found that the maximum value of () near TC reaches about 4.7 J/kg·K under the applied field change of 20 kOe, which is comparable to that of metal Gd ( of 2.8 J/kg K under 10 kOe), indicating the potential applications of PSMO-7 film in the field of magnetic refrigeration.

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Li, Zongbin, Yiwen Jiang, Zhenzhuang Li, César Fidel Sánchez Valdés, José Luis Sánchez Llamazares, Bo Yang, Yudong Zhang, Claude Esling, Xiang Zhao, and Liang Zuo. "Phase transition and magnetocaloric properties of Mn50Ni42−x Co x Sn8 (0 ≤ x ≤ 10) melt-spun ribbons." IUCrJ 5, no. 1 (January 1, 2018): 54–66. http://dx.doi.org/10.1107/s2052252517016220.

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The characteristics of magnetostructural coupling play a crucial role in the magnetic field-driven behaviour of magnetofunctional alloys. The availability of magnetostructural coupling over a broad temperature range is of great significance for scientific and technological purposes. This work demonstrates that strong magnetostrucural coupling can be achieved over a wide temperature range (222 to 355 K) in Co-doped high Mn-content Mn50Ni42−x Co x Sn8 (0 ≤ x ≤ 10) melt-spun ribbons. It is shown that, over a wide composition range with Co content from 3 to 9 at.%, the paramagnetic austenite first transforms into ferromagnetic austenite at T C on cooling, then the ferromagnetic austenite further transforms into a weakly magnetic martensite at T M. Such strong magnetostructural coupling enables the ribbons to exhibit field-induced inverse martensitic transformation behaviour and a large magnetocaloric effect. Under a field change of 5 T, a maximum magnetic entropy change ΔS M of 18.6 J kg−1 K−1 and an effective refrigerant capacity RC eff of up to 178 J kg−1 can be achieved, which are comparable with or even superior to those of Ni-rich Ni–Mn-based polycrystalline bulk alloys. The combination of high performance and low cost makes Mn–Ni–Co–Sn ribbons of great interest as potential candidates for magnetic refrigeration.

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Wang, Shiqi, Pu Liu, Jiamin Chen, and Weibin Cui. "Substitution effects on the magnetic phase transition and magnetocaloric effects in nanolaminated AlFe₂B₂ alloys." AIP Advances 12, no. 3 (March 1, 2022): 035235. http://dx.doi.org/10.1063/9.0000362.

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Substitution effects of V, Ti and C in AlFe2−xVxB2 ( x ≤ 0.15), AlFe2−yTiyB2 ( y ≤ 0.15) and AlFe2B2− zC z ( z ≤ 0.2) alloys have been investigated. The main phase of these alloys is crystallized in the orthorhombic Cmmm-type structure. The Curie temperature ( T c) of these compounds can be tuned from 278 K to be around 300 K depending on the substitution amount. No thermal and magnetic hysteresis can be observed, suggesting the magnetic transition of these alloys is the second-order nature. For a field change of 7 T, the maximum of entropy change (−ΔSmax) of 4.0 J Kg−1 K−1, 4.2 J Kg−1 K−1 and 3.9 J Kg−1 K−1 has obtained in AlFe1.9V0.1B2, AlFe1.9Ti0.1B2 and AlFe2B1.9C0.1 alloys. Tunable T c and wide temperature span in AlFe2B2 phase suggest that AlFe2B2-base alloys have a potential application as a refrigerant in magnetic refrigeration.

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Oumezzine, Marwène, Cristina Florentina Chirila, Iuliana Pasuk, Aurelian Catalin Galca, Aurel Leca, Bogdana Borca, and Victor Kuncser. "Magnetocaloric and Giant Magnetoresistance Effects in La-Ba-Mn-Ti-O Epitaxial Thin Films: Influence of Phase Transition and Magnetic Anisotropy." Materials 15, no. 22 (November 12, 2022): 8003. http://dx.doi.org/10.3390/ma15228003.

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Magnetic perovskite films have promising properties for use in energy-efficient spintronic devices and magnetic refrigeration. Here, an epitaxial ferromagnetic La0.67Ba0.33Mn0.95Ti0.05O3 (LBMTO-5) thin film was grown on SrTiO3(001) single crystal substrate by pulsed laser deposition. High-resolution X-ray diffraction proved the high crystallinity of the film with tetragonal symmetry. The magnetic, magnetocaloric and magnetoresistance properties at different directions of the applied magnetic field with respect to the ab plane of the film were investigated. An in-plane uni-axial magnetic anisotropy was evidenced. The LBMTO-5 epilayer exhibits a second-order ferromagnetic-paramagnetic phase transition around 234 K together with a metal–semiconductor transition close to this Curie temperature (TC). The magnetic entropy variation under 5 T induction of a magnetic field applied parallel to the film surface reaches a maximum of 17.27 mJ/cm3 K. The relative cooling power is 1400 mJ/cm3 K (53% of the reference value reported for bulk Gd) for the same applied magnetic field. Giant magnetoresistance of about 82% under 5 T is obtained at a temperature close to TC. Defined as the difference between specific resistivity obtained under 5 T with the current flowing along the magnetic easy axis and the magnetic field oriented transversally to the current, parallel and perpendicular to the sample plane, respectively, the in-plane magneto-resistance anisotropy in 5 T is about 9% near the TC.

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30

Jeong, Yeong Seung, M. S. Anwar, Faheem Ahmed, Seung Rok Lee, and Bon Heun Koo. "Study of Magnetic Transition and Magnetocaloric Effect in La_1-xSr_xMnO₃ (0.20≤ x ≤0.35) Compounds." Applied Mechanics and Materials 378 (August 2013): 225–29. http://dx.doi.org/10.4028/www.scientific.net/amm.378.225.

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We report the magnetic transition and large magnetic entropy change in Sr doped lanthanum manganites. Polycrystalline La1-xSrxMnO3(0.20x0.35) samples were prepared using the conventional solid-state reaction method. The results of X-ray diffraction indicates perovskite phase without any impurity. The magnetic study has revealed that the Curie temperature is influenced by Sr-concentration. The doping of Sr at La site affects the Mn-O bond length and Mn-O-Mn bond angle due to the difference in their ionic radii, consequently, the Curie temperature changed. A large magnetic entropy change has been observed for La0.8Sr0.2MnO3sample, the value of the maximum entropy change (SMmax) increases from 1.42 to 2.74 J/kgK as magnetic field increases from 1 to 2.5 T. This investigation suggests that La1-xSrxMnO3can be used as a potential magnetic refrigeration material.

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Botello-Zubiate, María, María Grijalva-Castillo, Daniel Soto-Parra, Renee Sáenz-Hernández, Carlos Santillán-Rodríguez, and José Matutes-Aquino. "Preparation of La0.7Ca0.3−xSrxMnO3 Manganites by Four Synthesis Methods and Their Influence on the Magnetic Properties and Relative Cooling Power." Materials 12, no. 2 (January 19, 2019): 309. http://dx.doi.org/10.3390/ma12020309.

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Manganites of the family La0.7Ca0.3−xSrxMnO3 were fabricated by four preparation methods: (a) the microwave-assisted sol-gel Pechini method; (b) sol-gel Pechini chemical synthesis; (c) solid-state reaction with a planetary mill; and (d) solid-state reaction with an attritor mill, in order to study the effect of the preparation route used on its magnetocaloric and magnetic properties. In addition, the manganites manufactured by the Pechini sol-gel method were compacted using Spark Plasma Sintering (SPS) to determine how the consolidation process influences its magnetocaloric properties. The Curie temperatures of manganites prepared by the different methods were determined in ~295 K, with the exception of those prepared by a solid-state reaction with an attritor mill which was 301 K, so there is no correlation between the particle size and the Curie temperature. All samples gave a positive slope in the Arrot plots, which implies that the samples underwent a second order Ferromagnetic (FM)–Paramagnetic (PM) phase transition. Pechini sol-gel manganite presents higher values of Relative Cooling Power (RCP) than the solid-state reaction manganite, because its entropy change curves are smaller, but wider, associated to the particle size obtained by the preparation method. The SPS technique proved to be easier and faster in producing consolidated solids for applications in active magnetic regenerative refrigeration compared with other compaction methods.

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32

Navarro-García, J. D., J. P. Camarillo-Garcia, F. Alvarado-Hernández, J. L. Sánchez Llamazares, and H. Flores-Zúñiga. "Elastocaloric and Magnetocaloric Effects Linked to the Martensitic Transformation in Bulk Ni55Fe11Mn7Ga27 Alloys Produced by Arc Melting and Spark Plasma Sintering." Metals 12, no. 2 (February 2, 2022): 273. http://dx.doi.org/10.3390/met12020273.

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The investigation of caloric effects linked to first-order structural transitions in Heusler-type alloys has become a subject of considerable current interest due to their potential utilization as refrigerants in solid-state cooling devices. This study is mainly motivated by the possibility of developing refrigeration devices of improved energy efficiency with a reduced environmental impact. We produced partially textured and isotropic bulk samples of the Heusler-type magnetic shape memory alloy Ni55Fe11Mn7Ga27 by arc melting and spark plasma sintering (SPS), respectively. Their structural, microstructural, and phase transition characteristics and magnetocaloric and elastocaloric effects, associated with first-order martensitic transformation (MT), were studied. The elemental chemical compositions of both samples were close to nominal, and a martensitic-like structural transformation appeared around room temperature with similar starting and finishing structural transition temperatures. At room temperature, austenite exhibited a highly ordered L21-type crystal structure. The partial grain orientation and isotropic nature of the arc-melted and SPS samples, respectively, were revealed by X-ray diffraction and SEM observations of the microstructure. For the arc-melted sample, austenite grains preferentially grew in the (100) direction parallel to the thermal gradient during solidification. The favorable effect of the texture on the elastocaloric response was demonstrated. Finally, due to its partial grain orientation, the arc-melted bulk sample showed superior values of maximum magnetic entropy change (|ΔSM|max = 18.6 Jkg−1K−1 at 5 T) and elastocaloric adiabatic temperature change (|ΔTadme|max = 2.4 K at 120 MPa) to those measured for the SPS sample (|ΔSM|max = 8.5 Jkg−1K−1 and (|ΔTadme|max = 0.8 K).

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Hassan, Najam ul, Mohsan Jelani, Ishfaq Ahmad Shah, Khalil Ur Rehman, Abdul Qayyum Khan, Shania Rehman, Muhammad Jamil, Deok-kee Kim, and Muhammad Farooq Khan. "Tunable Martensitic Transformation and Magnetic Properties of Sm-Doped NiMnSn Ferromagnetic Shape Memory Alloys." Crystals 11, no. 9 (September 13, 2021): 1115. http://dx.doi.org/10.3390/cryst11091115.

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NiMnSn ferromagnetic shape memory alloys exhibit martensitic transformation at low temperatures, restricting their applications. Therefore, this is a key factor in improving the martensitic transformation temperature, which is effectively carried out by proper element doping. In this research, we investigated the martensitic transformation and magnetic properties of Ni43Mn46-x SmxSn11 (x = 0, 1, 2, 3) alloys on the basis of structural and magnetic measurements. X-ray diffraction showed that the crystal structure transforms from the cubic L21 to the orthorhombic martensite and gamma (γ) phases. The reverse martensitic and martensitic transformations were indicated by exothermic and endothermic peaks in differential scanning calorimetry. The martensitic transformation temperature increased considerably with Sm doping and exceeded room temperature for Sm = 3 at. %. The Ni43Mn45SmSn11 alloy exhibited magnetostructural transformation, leading to a large magnetocaloric effect near room temperature. The existence of thermal hysteresis and the metamagnetic behavior of Ni43Mn45SmSn11 confirm the first-order magnetostructural transition. The magnetic entropy change reached 20 J·kg−1·K−1 at 266 K, and the refrigeration capacity reached ~162 J·Kg−1, for Ni43Mn45SmSn11 under a magnetic field variation of 0–5 T.

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Rana, Pooja, and U. P. Verma. "Theoretical Investigations of Structural Phase Transitions and Magnetic, Electronic and Thermal Properties of DyNi: Under High Pressures and Temperatures." ISRN Condensed Matter Physics 2014 (February 4, 2014): 1–7. http://dx.doi.org/10.1155/2014/763401.

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Present work is influenced by the requirement of investigation of rare earth intermetallics due to the nonavailability of theoretical details and least information from experimental results. An attempt has been made to analyse the structural, electronic, magnetic and thermal properties of DyNi using full potential linear augmented plane wave method based on density functional theory. DyNi differs from other members of lanthanides nickelates as in ground state it crystallizes in FeB phase rather than orthorhombic CrB structure. The equilibrium lattice constant, bulk modulus, and pressure derivative of bulk modulus are presented in four polymorphs (FeB, CrB, CsCl and NaCl) of DyNi. At equilibrium the cell volume of DyNi for FeB structure has been calculated as 1098.16 Bohr3 which is comparable well with the experimental value 1074.75 Bohr3. The electronic band structure has been presented for FeB phase. The results for thermal properties, namely, thermal expansion coefficient, Gruneisen parameter, specific heat and Debye temperature at higher pressure and temperatures have been reported. The magnetic moments at equilibrium lattice constants have also been tabulated as the rare earth ions associated with large magnetic moments increase their utility in industrial field for the fabrication of electronic devices due to their magnetocaloric effect used in magnetic refrigeration.

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Konopelnyk, Y., P. Iwanowski, R. Diduszko, T. Zajarniuk, J. Fink-Finowicki, I. Radelytskyi, A. Szewczyk, H. Szymczak, M. Pękala, and R. Puzniak. "Combined pressure and magnetic field induced caloric effects in Fe₇Se₈ single crystals doped with Ni and Co ions." Journal of Applied Physics 132, no. 17 (November 7, 2022): 173904. http://dx.doi.org/10.1063/5.0093024.

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The influence of Co and Ni ion doping on the crystal structure, phase transitions, and magnetic properties of the Fe7Se8 system has been investigated. The compounds studied are (Fe0.987Ni0.013)7Se8, (Fe0.955Ni0.045)7Se8, (Fe0.915Ni0.085)7Se8, (Fe0.89Ni0.11)7Se8, (Fe0.79Ni0.21)7Se8, (Fe0.975Co0.025)7Se8, (Fe0.951Co0.049)7Se8, and (Fe0.91Co0.09)7Se8 as well as the parent compound Fe7Se8. The crystals are grown using a modified Bridgman method and exist as a hexagonal NiAs-like structure with an ordered distribution of Fe vacancies that determine their magnetic properties. The substitution effect, inducing a systematic decrease in the unit-cell volume due to the ionic radii of doping ions being smaller than the radii of Fe2+ ions, is a source of chemical pressure, acting on the magnetic subsystem and determining the magnetic ordering temperature TC and the spin-reorientation temperature ( TSRT). As the most important result of this paper, it was shown that hydrostatic and chemical pressures are strongly correlated in the investigated system. The character of magnetic phase transitions has been designated in the vicinity of TC and TSRT temperatures, and the magnetic entropy change Δ Sm and refrigeration potential magnitudes have been determined for this temperature range. These magnetocaloric parameters were shown to depend strongly on chemical pressure. A phenomenological model developed based on the experimental measurements demonstrated that the magnetic properties of the system depend strongly on the crystal field acting on Fe2+ ions and the ratio of the numbers of Fe2+ and Fe3+ ions.

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Zong, Yun, and Di Kang. "Study on Influence of Ca²⁺ Ions Doping at a Site on Magnetic Properties and Magnetocaloric Effect of Nominal Compositions La_1.4Sr_1.6-xCa_xMn₂O₇." Advanced Materials Research 1120-1121 (July 2015): 406–13. http://dx.doi.org/10.4028/www.scientific.net/amr.1120-1121.406.

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Polycrystalline layered perovskite manganese oxides La1.4Sr1.6-xCaxMn2O7 (x=0,0.2,0.4,0.8,1.0,1.4,1.6) samples is prepared using solid state reaction.The XRD analysis shows that La1.4Sr1.6-xCaxMn2O7 (0 ≤ x ≤ 0.8) samples are Sr3Ti2O7-type tetragonal structure with space group I4/mmm and forms a layered perovskite structure; for the 1.0≤ x ≤1.6 series of samples the main phase is ABO3 type orthorhombic structure with space group Pbnm.For small amount of Ca2+ ion-doped sample (x= 0.2,0.4), induce serious Jahn-Teller(J-T) distortion of MnO6 octahedral.For a large number of doping (1.0≤ x ≤1.6) samples, ferromagnetic - paramagnetic transition occurs near the Curie temperature (Tc) from low to high temperatures.With increasing doping amount, the magnetization reached maximum at x=1.4 samples.Maximum magnetic entropy change of the three samples(x=1.0,1.4,1.6) reaches 0.84, 1.20 and 2.28 J kg-1 K-1 at 320,268 and 215K near the Curie temperature, respectively. The large magnetic entropy change effect under low magnetic field of the sample makes it an optimal candidate of room temperature magnetic refrigeration materials.

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Zhang, Lifeng, and Xiaofang Wu. "High-Efficiency Power Generation Device of Magnetic Declination Thermoelectric Material and Multisource Coordination Optimization of Distribution Network." Journal of Nanomaterials 2022 (June 1, 2022): 1–12. http://dx.doi.org/10.1155/2022/1705521.

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The first-order phase transition compounds have attracted widespread attention from refrigeration enterprises and scientists due to their giant magnetocaloric effect and refrigeration temperature region spanning room temperature. Magnetic substances are crystal structures composed of magnetic ions or atoms with a certain thermal motion or vibration. This research mainly discusses the multisource coordination optimization of magnetic declination thermoelectric material efficient power generation device and distribution network. In this study, large doses of MnFe(P,Si) compounds with different ratios were prepared. The reason for choosing a large dose is that the properties and structures of the samples prepared in a large amount and a small amount will be more or less the same for the samples fired in the same proportion and in the same process. At the same time, mass production also prepares for future mass production. Thermomagnetic power generation described in this study is a form of power generation that converts thermal energy directly into electrical energy. The conversion of thermal energy to electric energy is realized by the change of magnetization in the closed coil by the thermomagnetic material in the magnetic field environment, and then, the change of the magnetic flux in the closed coil is realized. The distribution network refers to the power network that receives electrical energy from the transmission network or regional power plants and distributes it locally through distribution facilities or distributes it to various users step by step according to the voltage. It is composed of overhead lines, cables, towers, distribution transformers, isolating switches, reactive power compensators, and some ancillary facilities. A network that plays an important role in distributing electrical energy in the power grid. This research starts with the active distribution network scheduling priority and the distribution network scheduling coordination control framework. Combined with the scheduling and operation characteristics of each component in the distribution network, the coordinated optimization scheme of the distribution network and the source-network load-storage coordinated control framework are investigated and analyzed. The scheduling resources of the model include the power of the substation flowing into the distribution network, the output of the adjustable distributed power source, the output value of the energy storage element, the closing status of the tie switch, and the section switch. In the study, it was found that when the Fe content was 0.63, the Curie temperature of the compound could reach 273 K at the highest. Scientifically designing a thermomagnetic power generation demonstration device is an important part of the realization of thermomagnetic power generation. The magnetic declination thermoelectric materials designed in this study will help to improve the power generation efficiency.

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Brück, Ekkes, Hargen Yibole, and Lian Zhang. "A universal metric for ferroic energy materials." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 374, no. 2074 (August 13, 2016): 20150303. http://dx.doi.org/10.1098/rsta.2015.0303.

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After almost 20 years of intensive research on magnetocaloric effects near room temperature, magnetic refrigeration with first-order magnetocaloric materials has come close to real-life applications. Many materials have been discussed as potential candidates to be used in multicaloric devices. However, phase transitions in ferroic materials are often hysteretic and a metric is needed to estimate the detrimental effects of this hysteresis. We propose the coefficient of refrigerant performance, which compares the net work in a reversible cycle with the positive work on the refrigerant, as a universal metric for ferroic materials. Here, we concentrate on examples from magnetocaloric materials and only consider one barocaloric experiment. This is mainly due to lack of data on electrocaloric materials. It appears that adjusting the field-induced transitions and the hysteresis effects can minimize the losses in first-order materials. This article is part of the themed issue ‘Taking the temperature of phase transitions in cool materials’.

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Shen, Jun, and Jian-Feng Wu. "Magnetocaloric effect and magnetic phase transition in Ho3Co." Journal of Applied Physics 109, no. 7 (April 2011): 07A931. http://dx.doi.org/10.1063/1.3561146.

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Wada, H., Y. Tanabe, K. Hagiwara, and M. Shiga. "Magnetic phase transition and magnetocaloric effect of DyMn2Ge2." Journal of Magnetism and Magnetic Materials 218, no. 2-3 (August 2000): 203–10. http://dx.doi.org/10.1016/s0304-8853(00)00410-8.

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Balli, Mohamed, Osmann Sari, L. Zamni, A. Robert, J. Forchelet, and Daniel Fruchart. "Bulk Transition Elements Based Materials for Magnetic Cooling Application." Solid State Phenomena 170 (April 2011): 248–52. http://dx.doi.org/10.4028/www.scientific.net/ssp.170.248.

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In this paper we investigate the performances of two bulk magnetocaloric refrigerants based on La(Fe,Co)13-xSix and prepared by powder metallurgy. Both materials were developed especially for a magnetic cooling machine. We have determined the magnetocaloric effect in term of temperature change under magnetic field using a test-bench with practical running conditions. ΔT was measured under 2 T and close to room temperature range. The obtained results will be compared with those of some reference materials reported in the literature. In addition, a composite material based on La(Fe,Co)13-xSix is proposed for magnetic systems using Ericsson and AMR cycles for refrigeration close to room temperature.

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Wang, Yi, Jun Yan, Yunlin Chen, and Qiuhong Cui. "The effects of Tb doping on the negative and positive magnetocaloric effects of Mn₃Ga_1−xTb_xC (0.02 ≤ x ≤ 0.05)." Journal of Applied Physics 132, no. 13 (October 7, 2022): 135108. http://dx.doi.org/10.1063/5.0111987.

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Generally, researchers focus on the great negative magnetocaloric effect (NMCE) rather than the positive magnetocaloric effect (PMCE) in Mn3GaC. Here, we prepared Mn3Ga1−xTbxC composites with a partial substitution of Ga by Tb. Tb doping expands the canted-ferromagnetic phase (CFM) between the anti-ferromagnetic and ferromagnetic phase in Mn3Ga0.97Tb0.03C. The CFM phase can be as a boundary to separate the NMCE from PMCE. It is possible to combine the NMCE and PMCE for refrigeration. Compared with NMCE in Mn3GaC, NMCE–PMCE combination in Mn3Ga0.97Tb0.03C displays a much larger operating temperature range without loss of magnetic entropy changes. Therefore, the NMCE–PMCE combination is valuable for improving the operating temperature range of magnetocaloric effect materials. It also provides a new idea for refrigeration applications.

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43

Dong, Q. Y., J. Chen, X. Q. Zhang, X. Q. Zheng, J. R. Sun, and B. G. Shen. "Magnetic phase transition and magnetocaloric effect in Dy12Co7 compound." Journal of Applied Physics 114, no. 17 (November 7, 2013): 173911. http://dx.doi.org/10.1063/1.4829281.

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Songlin, Dagula, O. Tegus, E. Brück, J. C. P. Klaasse, F. R. de Boer, and K. H. J. Buschow. "Magnetic phase transition and magnetocaloric effect in Mn5−xFexSi3." Journal of Alloys and Compounds 334, no. 1-2 (February 2002): 249–52. http://dx.doi.org/10.1016/s0925-8388(01)01776-5.

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Tishin, A. M. "Magnetocaloric effect in the vicinity of magnetic phase transition." Journal of Magnetism and Magnetic Materials 184, no. 1 (April 1998): 62–66. http://dx.doi.org/10.1016/s0304-8853(97)01113-x.

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Tishin, A. M., A. V. Derkach, Y. I. Spichkin, M. D. Kuz’min, A. S. Chernyshov, K. A. Gschneidner, and V. K. Pecharsky. "Magnetocaloric effect near a second-order magnetic phase transition." Journal of Magnetism and Magnetic Materials 310, no. 2 (March 2007): 2800–2804. http://dx.doi.org/10.1016/j.jmmm.2006.10.1056.

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Álvarez-Alonso, Pablo, Pedro Gorria, Jorge Sánchez Marcos, José L. Sánchez Llamazares, and Jesús A. Blanco. "The magnetocaloric effect in Er2Fe17near the magnetic phase transition." Journal of Physics: Condensed Matter 25, no. 49 (November 8, 2013): 496010. http://dx.doi.org/10.1088/0953-8984/25/49/496010.

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Palacios, Elías, Corrado Tomasi, Regino Saez-Puche, Antonio J. dos Santos-García, Francisco Fernandez-Martinez, and Ramón Burriel. "Enhanced Magnetocaloric Effect by the Rare Earth Polarization due to the Exchange with a Transition Metal - Study of GdCrO₄." Solid State Phenomena 257 (October 2016): 139–42. http://dx.doi.org/10.4028/www.scientific.net/ssp.257.139.

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The zircon polymorph of GdCrO4 has a large magnetocaloric effect over a wide temperature range, with |ΔST| > 20 J/kg·K from 6 K to 34 K, for a magnetic field of 9 T. This unusual behaviour is very interesting on magnetic refrigeration applications, for liquefying H2 or natural gas. The mean-field approach explains that it is due to the weaker Gd-Cr magnetic exchange relative to the Cr-Cr one, while the Gd-Gd exchange is negligible. This possibility has not been sufficiently studied and opens an interesting strategy to design more efficient materials for magnetic refrigeration.

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Phan, The-Long, T. D. Thanh, P. Zhang, D. S. Yang, and S. C. Yu. "The magnetic phase transition and magnetocaloric effect in Sm0.58Sr0.42MnO3 nanoparticles." Solid State Communications 166 (July 2013): 32–37. http://dx.doi.org/10.1016/j.ssc.2013.05.003.

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Mohapatra, Niharika, and E. V. Sampathkumaran. "Magnetic phase transition and magnetocaloric effect in PrCo9Si4 and NdCo9Si4." Solid State Communications 145, no. 9-10 (March 2008): 507–11. http://dx.doi.org/10.1016/j.ssc.2007.12.008.

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Journal articles on the topic 'Magnetocaloric effect, phase transition, magnetic refrigeration'

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