scholarly journals Simulated magnetocaloric properties of MnCr2O4 spinel

2016 ◽  
Vol 10 (1) ◽  
pp. 33-36 ◽  
Author(s):  
Mahmoud Hamad
Keyword(s):  
Entropy Change ◽  
Hydrogen Gas ◽  
Heat Capacity Change ◽  
Cooling Power ◽  
Active Magnetic Regenerator ◽  
Capacity Change ◽  
Magnetocaloric Properties ◽  
Prospective Application ◽  
Curie Temperatures ◽  
Magnetic Regenerator

The magnetocaloric properties of MnCr2O4 spinel have been simulated based on a phenomenological model. The simulation of magnetization as function of temperature is used to explore magnetocaloric properties such as magnetic entropy change, heat capacity change, and relative cooling power. The results imply the prospective application of MnCr2O4 spinel to achieve magnetocaloric effect at cryogenic temperatures (20-60K) near Curie temperatures (38-44K). According to the obtained results it is recommended that MnCr2O4 spinel can be used as a promising practical material in the active magnetic regenerator cycle that cools hydrogen gas.

scholarly journals Magnetocaloric properties of La0.666Sr0.373Mn0.943Cu0.018O3

2017 ◽  
Vol 11 (3) ◽  
pp. 225-228 ◽  
Author(s):  
Mahmoud Hamad
Keyword(s):  
Magnetocaloric Effect ◽  
Magnetic Entropy Change ◽  
Entropy Change ◽  
Cooling Power ◽  
Magnetic Entropy ◽  
Active Magnetic Regenerator ◽  
Magnetocaloric Properties ◽  
Magnetic Specific Heat ◽  
Prospective Application ◽  
Magnetic Regenerator

Magnetocaloric properties of La0.666Sr0.373Mn0.943Cu0.018O3 (LSMCO) perovskite (such as magnetic entropy change, full-width at half-maximum, relative cooling power and magnetic specific heat change) at applied magnetic field of 0.05 T were calculated using the phenomenological model. The results indicate the prospective application of LSMCO due to high magnetocaloric effect near the Curie temperature. Furthermore, the magnetocaloric properties of LSMCO sample are comparable with magnetocaloric properties of MnAs film, La1-xCdxMnO3 and La1.25Sr0.75MnCoO6, and significantly larger than that of Gd1-xCaxBaCo2O5.5 and Ge0.95Mn0.05. It is recommended that magnetocaloric effect of LSMCO can be used as a promising practical material of an apparatus based on the active magnetic regenerator cycle.

scholarly journals Magnetocaloric effect in Sr2FeMoO6/Ag composites

2015 ◽  
Vol 9 (1) ◽  
pp. 11-15 ◽  
Author(s):  
Mahmoud Hamad
Keyword(s):  
Magnetocaloric Effect ◽  
Magnetic Entropy Change ◽  
Double Perovskite ◽  
Entropy Change ◽  
Heat Capacity Change ◽  
Cooling Power ◽  
Magnetic Entropy ◽  
Low Field ◽  
Capacity Change ◽  
Magnetocaloric Properties

The enhanced low-field magnetocaloric effect was investigated for double perovskite Sr2FeMoO6 - silver (SFMO/Ag) composites with 0, 5 and 10 wt.% of Ag. A phenomenological model was used to predict magnetocaloric properties of SFMO/Ag composites, such as magnetic entropy change, heat capacity change and relative cooling power. It was shown that magnetic entropy change (?S M) peaks of SFMO/Ag span over a wide temperature region, which can significantly improve the global efficiency of the magnetic refrigeration. Furthermore, the ?S M distribution of the SFMO/Ag composites is much more uniform than that of gadolinium. Through these results, SFMO/Ag composite has some potential application for magnetic refrigerants in an extended high-temperature range.

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.

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.

Magnetic refrigeration with GdN by Active Magnetic Refrigerator cycle

2011 ◽  
Vol 1310 ◽  
Author(s):  
Yusuke Hirayama ◽  
Hiroyuki Okada ◽  
Takashi Nakagawa ◽  
Takao. A. Yamamoto ◽  
Takafumi Kusunose ◽  
...  
Keyword(s):  
Magnetic Entropy Change ◽  
Hot Isostatic Pressing ◽  
Entropy Change ◽  
Magnetic Refrigeration ◽  
Zero Field ◽  
Active Magnetic Regenerator ◽  
Magnetic Field Change ◽  
Total Temperature ◽  
The Magnetic Field ◽  
Magnetic Regenerator

ABSTRACTA magnetic refrigeration test was performed using a test device filled with spherical GdN material synthesized by the hot isostatic pressing (HIP) method. Refrigeration with an active magnetic regenerator cycle was tested in the temperature range between 48 and 66 K, with the field changing from 1.2 to 3.7 T and 2.0 to 4.0 T at upper and lower sides of the regenerator bed filled with the GdN spheres, respectively. Temperature spans about of 2 K were obtained at both sides, and the total temperature span in each cycle attained about 5 K. The specific heat of the material was measured to calculate the magnetic entropy change ΔS and the adiabatic temperature change ΔT induced by the magnetic field change ΔH. It was suggested that for a given ΔH, larger ΔS and ΔT can be exploited when demagnetized to lower H, especially, to zero field.

scholarly journals Structural, Magnetic, and Magnetocaloric Properties of R2NiMnO6 (R = Eu, Gd, Tb)

2021 ◽  
Author(s):  
K.P. Shinde ◽  
E.J. Lee ◽  
Maykel Manawan ◽  
A. Lee ◽  
S.Y. Park ◽  
...  
Keyword(s):  
Magnetic Entropy Change ◽  
Ceramic Powder ◽  
Double Perovskite ◽  
Entropy Change ◽  
Cooling Power ◽  
X Ray Diffraction ◽  
Atomic Size ◽  
X Ray ◽  
Magnetocaloric Properties ◽  
Group A

Abstract Double perovskite Eu2NiMnO6 (ENMO) Gd2NiMnO6 (GNMO) and Tb2NiMnO6 (TNMO) ceramic powder have been synthesized by solid-state reaction and their crystal structure, microstructure, cryogenic magnetic properties, and magnetocaloric performance have been investigated. Structural studies by using X-ray diffraction shows that all compounds crystallize in the monoclinic structure with a P21/n space group. A ferromagnetic to paramagnetic (FM-PM) second-order phase transition occurred in ENMO, GNMO, and TNMO around 143, 130, and 112 K, respectively. The values of maximum magnetic entropy change and relative cooling power at an applied field of 5 T are found to be 3.2, 3.8, 3.5 J/kgK and 150, 182, 176 J/kg respectively, for the studied sample. The change in structural, magnetic, and magnetocaloric effect ascribed to the superexchange mechanism of Ni2+ – O – Mn3+ and Ni2+ – O – Mn4+. Due to different atomic size of Eu, Gd, Tb changes the ratio of Mn4+/Mn3+ which is responsible for the variation of properties significantly in double perovskite.

Tailoring the Magnetic Properties and Magnetocaloric Effect in Double Perovskites Sr2FeMo1–xNbxO6

2020 ◽  
Vol 12 (3) ◽  
pp. 391-397 ◽  
Author(s):  
Imad Hussain ◽  
S. N. Khan ◽  
Tentu Nageswara Rao ◽  
Riyaz Uddin ◽  
Jong Woo Kim ◽  
...  
Keyword(s):  
Magnetic Measurements ◽  
Spontaneous Magnetization ◽  
Double Perovskite ◽  
Entropy Change ◽  
Solid State Reaction Method ◽  
Cooling Power ◽  
X Ray Diffraction ◽  
Site Disorder ◽  
Magnetocaloric Properties ◽  
Arrott Plots

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.

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.

Magnetocaloric Properties of Perovskite-Type Manganite La0.65Sr0.2Na0.15MnO3

2016 ◽  
Vol 697 ◽  
pp. 93-96 ◽  
Author(s):  
Qing Ling Ji ◽  
Zheng Guang Zou ◽  
Fei Long ◽  
Yi Wu
Keyword(s):  
Curie Temperature ◽  
Magnetic Entropy Change ◽  
Sol Gel ◽  
Entropy Change ◽  
Cooling Power ◽  
Diffraction Measurement ◽  
Field Variation ◽  
X Ray Diffraction ◽  
Magnetocaloric Properties ◽  
Perovskite Type

Polycrystalline perovskite-type manganite La0.65Sr0.2Na0.15MnO3 was prepared by sol-gel method. An X-ray diffraction measurement showed that the sample was a single phase. The Curie temperature of the sample was determined to be 350K. The maximum magnetic entropy change |ΔSM| corresponding to a 1T magnetic field variation was found to be 1.08 J/kg K and about 40.6 J/kg of relative cooling power was obtained near the Curie temperature. The first-order or the second-order on the phase transition of the manganite was distinguished by Banerjee criteria.

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