On the broadening of the magnetic entropy change due to Curie temperature distribution

The magnetic and magnetothermal properties of the non-stoichiometric TbCo2Nix (0 ≤ x ≤ 0.2) alloys were studied. It was found that the concentration dependence of the Curie temperature and magnetic moment of the 3d-sublattice have a maximum at x = 0.025. The obtained experimental magnetic properties of the TbCo2Nix alloys were discussed under assumption that the Co magnetic moment in the compounds changes with increasing x. The magnetic entropy change was determined using the temperature dependences of the magnetization and Maxwell’s thermodynamic relation. The obtained results for TbCo2Nix were compared with those for the ErCo2Mnx alloys.

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Study of Magnetic Transition and Magnetocaloric Effect in La1-xSrxMnO3 (0.20≤ x ≤0.35) Compounds

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.378.225 ◽

2013 ◽

Vol 378 ◽

pp. 225-229 ◽

Cited By ~ 1

Author(s):

Yeong Seung Jeong ◽

M.S. Anwar ◽

Faheem Ahmed ◽

Seung Rok Lee ◽

Bon Heun Koo

Keyword(s):

Curie Temperature ◽

Magnetic Entropy Change ◽

Perovskite Phase ◽

Magnetic Transition ◽

Entropy Change ◽

Solid State Reaction Method ◽

Magnetic Entropy ◽

Conventional Solid State Reaction ◽

Ionic Radii ◽

The Difference

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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Study on Influence of Ca2+ Ions Doping at a Site on Magnetic Properties and Magnetocaloric Effect of Nominal Compositions La1.4Sr1.6-xCaxMn2O7

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1120-1121.406 ◽

2015 ◽

Vol 1120-1121 ◽

pp. 406-413 ◽

Cited By ~ 1

Author(s):

Yun Zong ◽

Di Kang

Keyword(s):

Curie Temperature ◽

Manganese Oxides ◽

Magnetic Entropy Change ◽

Entropy Change ◽

Xrd Analysis ◽

Layered Perovskite ◽

Magnetic Entropy ◽

Doping Amount ◽

Space Group ◽

Room Temperature Magnetic Refrigeration

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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Field Dependence of the Refrigerant Capacity for La0.6Ca0.4MnO3 Manganite

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.154.163 ◽

2009 ◽

Vol 154 ◽

pp. 163-168 ◽

Cited By ~ 1

Author(s):

R.A. Szymczak ◽

Aleksandra Kolano-Burian ◽

Roman Kolano ◽

R. Puzniak ◽

V.P. Dyakonov ◽

...

Keyword(s):

Magnetic Field ◽

Curie Temperature ◽

Statistical Model ◽

Magnetic Entropy Change ◽

Entropy Change ◽

Relative Cooling Power ◽

Cooling Power ◽

Magnetic Entropy ◽

Refrigerant Capacity ◽

Jahn Teller

The magnetocaloric effect in La0.6Ca0.4MnO3 manganite has been investigated. The isothermal magnetization versus applied magnetic field at various temperatures in the vicinity of Curie temperature was measured, and the temperature dependence of magnetic entropy change was determined using Maxwell’s relation. This value is comparable to that in Gd. Nevertheless, the relative cooling power of La0.6Ca0.4MnO3 was shown to be considerably lower than that of Gd. The experimental results have been analyzed in frames of a phenomenological statistical model. This model considers explicitly Jahn-Teller interactions and allows prediction of the field dependences of the magnetic entropy change and the relative cooling power.

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Magnetic entropy change and magnetic properties of LaFe 11.5 Si 1.5 after controlling the Curie temperature by partial substitution of Mn and hydrogenation

Chinese Physics B ◽

10.1088/1674-1056/25/2/027501 ◽

2016 ◽

Vol 25 (2) ◽

pp. 027501 ◽

Cited By ~ 2

Author(s):

Bin Fu ◽

Jie Han

Keyword(s):

Magnetic Properties ◽

Curie Temperature ◽

Magnetic Entropy Change ◽

Entropy Change ◽

Partial Substitution ◽

Magnetic Entropy

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Compositional Dependence of Curie Temperature and Magnetic Entropy Change in the Amorphous Tb–Co Ribbons

Materials ◽

10.3390/ma14041002 ◽

2021 ◽

Vol 14 (4) ◽

pp. 1002

Author(s):

Xin Wang ◽

Ding Ding ◽

Li Cui ◽

Lei Xia

Keyword(s):

Curie Temperature ◽

Linear Relationship ◽

Metallic Glasses ◽

Amorphous Alloys ◽

Magnetic Entropy Change ◽

Alloy Composition ◽

Entropy Change ◽

Magnetic Entropy ◽

Compositional Dependence ◽

Curie Temperature Tc

The Curie temperature (Tc) and magnetic entropy change (−ΔSm), and their relationship to the alloy composition of Tb–Co metallic glasses, were studied systematically in this paper. It was found that, in contrast to the situation in amorphous Gd–Co ribbons, the dependence of Tc on Tb content and the maximum −ΔSm vs. Tc -2/3 plots in Tb–Co binary amorphous alloys do not follow a linear relationship, both of which are supposed to be closely related to the non-linear compositional dependence of Tb–Co interaction due to the existence of orbital momentum in Tb.

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Observation of Griffiths Phase, Critical Exponent Analysis and High Magnetocaloric Effect Near Room Temperature at Low Magnetic Field in V doped La0.7Sr0.3MnO3

Journal of Physics D Applied Physics ◽

10.1088/1361-6463/ac4a99 ◽

2022 ◽

Author(s):

Jagadish Kumar Galivarapu ◽

Ashika Jose ◽

Erappanal Padmanabhan Jinu ◽

Thirumalainaidu Thiagarajan Saravanan ◽

Senthil Kumar Eswaran ◽

...

Keyword(s):

Magnetic Fields ◽

Curie Temperature ◽

Critical Exponent ◽

Critical Exponents ◽

Room Temperature ◽

Magnetic Entropy Change ◽

Entropy Change ◽

Magnetic Entropy ◽

Griffiths Phase ◽

Vanadium Doping

Abstract We report on observation of Griffiths phase, high magnetocaloric properties at low magnetic fields and temperature dependent critical exponents of La0.7Sr0.3VxMn1-xO3 (x=0, 0.05 & 0.1) perovskite bulk materials. The Curie temperature (TC) of pure La0.7Sr0.3MnO3 is seen to be 368.7 K and decreases towards room temperature (342.2 K) by 10 mol% vanadium doping at the Mn site. Vanadium doping leads to enhancement in magnetic entropy change (-SM) from 1 Jkg-1K-1to 1.41 Jkg-1K-1. Vanadium doping at Mn site leads to the formation of Griffiths phase, a magnetic disorder due to the co-existence of paramagnetic matrix and short range ferromagnetic clusters. X-ray photoelectron spectroscopy analysis confirm the presence of mixed valance V4+/V5+along with Mn3+/ Mn4+ ions contributing to various double exchange interactions. Nature of phase transitions and magnetic interactions are analyzed by evaluating critical exponents and. All the samples show second-order ferromagnetic (FM) to paramagnetic (PM) phase transition, confirmed from the modified Arrott’s plots and critical exponent analysis carried out using Kouvel-Fisher method. Enhancement in magnetic entropy change along with the decrease in Curie temperature towards room temperature by vanadium doping in the La0.7Sr0.3MnO3 oxides indicates the possible application of these materials for the magnetic refrigeration at low magnetic fields.

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