scholarly journals Critical dependence of magnetostructural coupling and magnetocaloric effect on particle size in Mn-Fe-Ni-Ge compounds

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Rongrong Wu ◽  
Feiran Shen ◽  
Fengxia Hu ◽  
Jing Wang ◽  
Lifu Bao ◽  
...  
Keyword(s):  
Particle Size ◽  
Magnetocaloric Effect ◽  
Magnetic Transition ◽  
Magnetic Hysteresis ◽  
Negative Thermal Expansion ◽  
Entropy Change ◽  
Cooling Power ◽  
Austenitic Phase ◽  
Magnetic Actuators ◽  
Practical Applications

Abstract Magnetostructural coupling, which is the coincidence of crystallographic and magnetic transition, has obtained intense attention for its abundant magnetoresponse effects and promising technological applications, such as solid-state refrigeration, magnetic actuators and sensors. The hexagonal Ni2In-type compounds have attracted much attraction due to the strong magnetostructural coupling and the resulted giant negative thermal expansion and magnetocaloric effect. However, the as-prepared samples are quite brittle and naturally collapse into powders. Here, we report the effect of particle size on the magnetostructural coupling and magnetocaloric effect in the Ni2In-type Mn-Fe-Ni-Ge compound, which undergoes a large lattice change across the transformation from paramagnetic austenite to ferromagnetic martensite. The disappearance of martensitic transformation in a large amount of austenitic phase with reducing particle size, to our best knowledge, has not been reported up to now. The ratio can be as high as 40.6% when the MnNi0.8Fe0.2Ge bulk was broken into particles in the size range of 5~15 μm. Meanwhile, the remained magnetostructural transition gets wider and the magnetic hysteresis becomes smaller. As a result, the entropy change drops, but the effective cooling power RC effe increases and attains to the maximum at particles in the range of 20~40 μm. These observations provide constructive information and highly benefit practical applications for this class of novel magnetoresponse materials.

scholarly journals Tuning magnetic and magnetocaloric properties of Pr0.6Sr0.4MnO3 through size modifications

2021 ◽  
Author(s):  
Anita D Souza ◽  
Megha Vagadia ◽  
Mamatha Daivajna
Keyword(s):  
Particle Size ◽  
Magnetic Transition ◽  
Entropy Change ◽  
Cooling Power ◽  
Magnetic Transition Temperature ◽  
Temperature Range ◽  
Spin Disorder ◽  
Magnetocaloric Properties ◽  
Surface Disorder ◽  
Enhanced Surface

AbstractParticle size as an effective tool for controlling the magnetic and magnetocaloric properties of Pr0.6Sr0.4MnO3 samples has been studied. In the present work, a direct influence of particle size on the magnitude of magnetization and magnetic transition temperature, TC, can be seen. The TC drops from 309 to 242 K, while the saturation magnetization (MS) decreases from 3.6 to 0.5 μB/f.u. as the particle changes from 120 to 9 nm. Concurrently, coercivity (HC) exhibits a drastic rise emphasizing the enhanced surface disorder in the nanoparticles. Another interesting observation is in the magnetic entropy change, ΔS, which though decreases in magnitude from 5.51 to 3.90 J/Kg-K as particle size decreases from 120 to 30 nm, but the temperature range of ΔS (i.e., relative cooling power, RCP) increases from 184.33 to 228.85 J/Kg. Such interplay between magnitude and wider temperature range of ΔS, which can be fine-tuned by particle size, provides an interesting tool for using surface spin disorder, as a control mechanism in modifying physical properties.

Magnetic and magnetocaloric effect in a stuffed honeycomb polycrystalline antiferromagnet GdInO3

2021 ◽  
Author(s):  
Yao-Dong Wu ◽  
Wei-Wei Duan ◽  
Qiu-Yue Li ◽  
Yong-Liang Qin ◽  
Zhen-Fa Zi ◽  
...  
Keyword(s):  
Magnetocaloric Effect ◽  
Magnetic Entropy Change ◽  
Magnetic System ◽  
Magnetic Hysteresis ◽  
Entropy Change ◽  
Cooling Power ◽  
Magnetic Entropy ◽  
Antiferromagnetic Ordering ◽  
Magnetocaloric Properties ◽  
The Magnetic Field

Abstract The magnetic and magnetocaloric properties were studied in a stuffed honeycomb polycrystalline antiferromagnet GdInO3. The onset temperature of antiferromagnetic ordering was observed at ~ 2.1 K. Negligible thermal and magnetic hysteresis suggest a reversible magnetocaloric effect (MCE) in the GdInO3 compound. In the magnetic field changes of 0–50 kOe and 0–70 kOe, the maximum magnetic entropy change values are 9.65 J/kg K and 18.37 J/kg K, respectively, near the liquid helium temperature, with the corresponding relative cooling power values of 115.01 J/kg and 211.31 J/kg. The MCE investigation of the polycrystalline GdInO3 serves to illuminate more exotic properties in this frustrated stuffed honeycomb magnetic system.

Tunable magnetocaloric effect in La0.7Ca0.3MnO3 nanoparticles

2018 ◽  
Vol 32 (26) ◽  
pp. 1850290
Author(s):  
S. Qaseem ◽  
M. Naeem ◽  
S. Rizwan Ali
Keyword(s):  
Particle Size ◽  
Magnetocaloric Effect ◽  
Magnetic Transition ◽  
Second Order ◽  
Gradual Transition ◽  
Cooling Power ◽  
Zero Field ◽  
Colossal Magnetoresistive ◽  
Three Samples ◽  
Saturation Region

We study ferromagnetic to paramagnetic transition using Banerjee criterion in colossal magnetoresistive La[Formula: see text]Ca[Formula: see text]MnO3 nanoparticles of different sizes (20, 26 and 32 nm). These particles are chemically prepared by a modified citrate route. Particle sizes are estimated by X-ray diffraction (XRD). Sample morphology and size distribution are examined by a transmission electron microscope. Order of transition is determined by measuring magnetic field dependence of magnetization near Curie temperature T[Formula: see text]. Our results reveal second-order magnetic transition in all three different-sized particles in contrast to the first-order transition reported in bulk samples. This is further supported by temperature dependences of zero-field-cooled (ZFC) and field-cooled (FC) magnetizations. FC curves show gradual transition for all three samples without any saturation region as is the case of bulk. T[Formula: see text] is extracted from ZFC curves and is found to be 240 K for 20 nm particles and 258 K for both 26 and 32 nm particles. Magnetocaloric effect as a function of particle size also confirms the second-order magnetic transition in all three samples. The relative cooling power at 20 kOe is found to be decreasing with decreasing particle size.

scholarly journals Magnetic Properties and Magnetocaloric Effect in Gd100-xCox Thin Films

Crystals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 278 ◽  
Author(s):  
Mohamed Tadout ◽  
Charles-Henri Lambert ◽  
Mohammed El Hadri ◽  
Abdelilah Benyoussef ◽  
Mohammed Hamedoun ◽  
...  
Keyword(s):  
Thin Films ◽  
Magnetocaloric Effect ◽  
Magnetic Entropy Change ◽  
Entropy Change ◽  
Magnetic Thin Films ◽  
Critical Parameters ◽  
Cooling Power ◽  
Magnetocaloric Properties ◽  
Co Concentration ◽  
Key Parameter

We investigated the magnetic and magnetocaloric properties of Gd100-xCox ( x = 40 to 56) thin films fabricated by the sputtering technique. Under an applied field change Δ H = 20 kOe , the magnetic entropy change ( Δ S m ) decreases from 2.64 Jkg−1K−1 for x = 44 to about 1.27 Jkg−1K−1 for x = 56. Increasing the Co concentration from x = 40 to 56 shifts the Curie temperature of Gd100-xCox ( x = 40 to 56) thin films from 180 K toward 337 K. Moreover, we extracted the values of critical parameters Tc, β, γ, and δ by using the modified Arrott plot methods. The results indicate the presence of a long-range ferromagnetic order. More importantly, we showed that the relative cooling power (RCP), which is a key parameter in magnetic refrigeration applications, is strongly enhanced by changing the Co concentration in the Gd100-xCox thin films. Our findings help pave the way toward the enhancement of the magnetocaloric effect in magnetic thin films.

Magnetic Properties and Magnetocaloric Effect of Gd3Ni in Crystalline and Amorphous States

2012 ◽  
Vol 190 ◽  
pp. 355-358 ◽  
Author(s):  
D.A. Shishkin ◽  
N.V. Baranov ◽  
A.V. Proshkin ◽  
S.V. Andreev ◽  
A.S. Volegov
Keyword(s):  
Magnetic Field ◽  
Magnetocaloric Effect ◽  
Entropy Change ◽  
Rapid Quenching ◽  
Antiferromagnetic Order ◽  
Cooling Power ◽  
Ferromagnetic Behavior ◽  
Field Change ◽  
Ni Alloy ◽  
Magnetic Field Change

The liquid quenched Gd3Ni alloy is observed to exhibit a ferromagnetic behavior below TC = 117 K unlike crystalline compound having an antiferromagnetic order at T < TN = 99 K. Rapid quenching from the melt results in a considerable enhancement of the magnetocaloric effect in Gd3Ni at low magnetic fields. The maximal value of the isothermal magnetic entropy change at a magnetic field change of 20 kOe for the amorphous Gd3Ni surpasses by more than 8 times the SM value for the polycrystalline counterpart. The relative cooling power for the amorphous Gd3Ni alloy is estimated as 265 J kg-1 and 676 J kg-1 at a magnetic field change of 20 kOe and 50 kOe, respectively.

Magnetic Properties and Magnetocaloric Effect of Nd0.7Gd0.3Mn2Si2 Alloy

2017 ◽  
Vol 1142 ◽  
pp. 47-52 ◽  
Author(s):  
Shi Dong Lin ◽  
Xiao Long Chen ◽  
Jiang Wang ◽  
Chao Fan Zhu ◽  
Mao Hua Rong ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetocaloric Effect ◽  
Physical Property Measurement System ◽  
Physical Property ◽  
Entropy Change ◽  
Spin Reorientation ◽  
Cooling Power ◽  
Field Change ◽  
X Ray Diffraction ◽  
Scanning Calorimetry

In this work, crystal structure, magnetic properties and magnetocaloric effect of Nd0.7Gd0.3Mn2Si2 alloy were studied by X-ray diffraction (XRD), Physical Property Measurement System (PPMS) and Differential Scanning Calorimetry (DSC). Nd0.7Gd0.3Mn2Si2 crystallizes in ThCr2Si2-typed structure with space group I4/mmm, in which the Nd, Gd, Mn and Si atoms occupy 2a (0, 0, 0), 2a (0, 0, 0), 4d (0, 1/2, 1/4) and 4e (0, 0, 0.38261) position, respectively. The Curie temperature (Tc) of Nd0.7Gd0.3Mn2Si2 alloy is 42 K, while the spin reorientation temperature (TSR) is 26 K and the Nel temperature (TN) is 410 K. The Tc and TN were determined using PPMS and DSC, respectively. The maximum value of the magnetic entropy change (-Smax) in the field change of 0-5 T is 11.862 J/kg K, while the value of relative cooling power (RCP) in Nd0.7Gd0.3Mn2Si2 alloy is 69.666 J/kg under the field change of 5 T.

scholarly journals Observation of a Broadened Magnetocaloric Effect in Partially Crystallized Gd60Co40 Amorphous Alloy

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1741
Author(s):  
Ping Han ◽  
Ziyang Zhang ◽  
Jia Tan ◽  
Xue Zhang ◽  
Yafang Xu ◽  
...  
Keyword(s):  
Amorphous Alloy ◽  
Magnetocaloric Effect ◽  
Magnetic Entropy Change ◽  
Amorphous Matrix ◽  
Thermodynamic Cycle ◽  
Entropy Change ◽  
Cooling Power ◽  
Magnetic Entropy ◽  
Amorphous Precursor ◽  
Space Group

To investigate the effect of crystallization treatment on the structure and magnetocaloric effect of Gd60Co40 amorphous alloy, the melt-spun ribbons were annealed at 513 K isothermally for 20, 40 and 60 min. The results indicate that, with increasing annealing time, the Gd4Co3 (space group P63/m) and Gd12Co7 (space group P21/c) phases precipitated from the amorphous precursor in sequence. In particular, in the samples annealed for 40 and 60 min, three successive magnetic transitions corresponding to the phases of Gd4Co3, Gd12Co7 and remaining amorphous matrix were detected, which induced an overlapped broadened profile of magnetic entropy change (|ΔSM|) versus temperature. Under magnetic field changing from 0 to 5 T, |ΔSM| values of 6.65 ± 0.1 kg−1·K−1 and 6.44 ± 0.1 J kg−1·K−1 in the temperature spans of 180–196 K and 177–196 K were obtained in ribbons annealed for 40 and 60 min, respectively. Compared with the fully amorphous alloy, the enhanced relative cooling power and flattened magnetocaloric effect of partially crystallized composites making them more suitable for the Ericsson thermodynamic cycle.

Untypical Temperature Dependence of the Magnetocaloric Effect in the Dy(Co1-xFex)2 (x = 0.10; 0.15) Compounds

2015 ◽  
Vol 233-234 ◽  
pp. 247-250 ◽  
Author(s):  
Maksim S. Anikin ◽  
Evgeniy N. Tarasov ◽  
Nikolay V. Kudrevatykh ◽  
Aleksander V. Zinin
Keyword(s):  
Magnetic Field ◽  
Temperature Dependence ◽  
Magnetic Entropy Change ◽  
Magnetic Transition ◽  
Iron Concentration ◽  
Entropy Change ◽  
Cooling Power ◽  
X Ray Diffraction ◽  
Magnetocaloric Properties ◽  
Ordered State

A study of crystalline structure, magnetic and magnetocaloric properties of Dy(Co1-хFeх)2 (х = 0.10, 0.15) intermetallic compounds was undertaken. Phase composition was controlled by X-ray diffraction analysis. Magnetic properties were measured with a help of SQUID magnetometer in magnetic fields up to 7 Т in the temperature range from 4.2 K to 400 K. Magnetic transition temperatures from paramagnetic to magnetically ordered state were inferred as 288 K and 350 K, respectively. It is shown that at an increase of iron concentration and/or magnetic field intensity, a considerable maximum broadenings on a temperature dependence of magnetic entropy change is observed. The calculated value of the relative cooling power (RCP) of Dy(Co0.90Fe0.10)2, in a magnetic field of 1.7 T is equal to 152 J/kg that is close to that for Gd metal with RCP = 181 J/kg at μ0Н = 2 T.

scholarly journals Direct and Indirect Determination of the Magnetocaloric Effect in the Heusler Compound Ni1.7Pt0.3MnGa

Entropy ◽  
2021 ◽  
Vol 23 (10) ◽  
pp. 1273
Author(s):  
Ricardo D. dos Reis ◽  
Luana Caron ◽  
Sanjay Singh ◽  
Claudia Felser ◽  
Michael Nicklas
Keyword(s):  
Magnetocaloric Effect ◽  
Direct Methods ◽  
Entropy Change ◽  
Measuring Method ◽  
Martensitic Transition ◽  
Magnetic Shape Memory ◽  
Flow Measurements ◽  
Indirect Determination ◽  
Practical Applications ◽  
First Order

Magnetic shape-memory materials are potential magnetic refrigerants, due the caloric properties of their magnetic-field-induced martensitic transformation. The first-order nature of the martensitic transition may be the origin of hysteresis effects that can hinder practical applications. Moreover, the presence of latent heat in these transitions requires direct methods to measure the entropy and to correctly analyze the magnetocaloric effect. Here, we investigated the magnetocaloric effect in the Heusler material Ni1.7Pt0.3MnGa by combining an indirect approach to determine the entropy change from isofield magnetization curves and direct heat-flow measurements using a Peltier calorimeter. Our results demonstrate that the magnetic entropy change ΔS in the vicinity of the first-order martensitic phase transition depends on the measuring method and is directly connected with the temperature and field history of the experimental processes.

Non-Monotonic Variation of Magnetocaloric Effect in the Tm2(Fe,Mn)17 and Tm2Fe16-Tm2Fe19 Systems

2016 ◽  
Vol 845 ◽  
pp. 13-16
Author(s):  
Anatoly G. Kuchin ◽  
Sergey P. Platonov ◽  
Wacław Iwasieczko
Keyword(s):  
Magnetocaloric Effect ◽  
Magnetic Measurements ◽  
Entropy Change ◽  
Relative Cooling Power ◽  
Cooling Power ◽  
Fe Content ◽  
Ferromagnetic Ordering ◽  
Two Peaks

The magnetocaloric effect (MCE) of the Tm2Fe17-xMnx (x = 0, 0.2, 0.5, 1, 1.5) and Tm2Fe16, Tm2Fe17, Tm2Fe18, Tm2Fe19 compounds has been investigated by means of magnetic measurements. The MCE exhibits two peaks near the temperatures of ferromagnetic ordering ΘT and TN for Tm2Fe17, Tm2Fe18, Tm2Fe19 compositions or one peak near TC for the Tm2Fe16 and Tm2Fe17-xMnx (x ≥ 0.2) ferromagnets. The peak entropy change -ΔSM varies non-monotonically in the systems, with the maximal values-3.25 J/kg K at T = 310 for Tm2Fe16.8Mn0.2 and-3.5 J/kg K at T = 290 K for Tm2Fe17 in a field of 5 T. On the contrary, the relative cooling power decreases monotonically with decrease of Fe content because of contraction of the -ΔSM peaks.

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