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result(s) for
"Hamad, Mahmoud"
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The remarkable impact of nitridation temperature on the magnetocaloric effect of CoFe2/MgO matrix
In this study, a phenomenological model is used to predict the magnetocaloric effect (MCE) of two CoFe
2
/MgO nanocomposite samples exposed to nitridation reactions at nitridation temperatures of 400 and 500 °C (they are indicated as N400 and N500, respectively). The findings show that, within the investigated temperature range, the MCE of the N400 sample is conventional with full-width at half-maximum (
δ
T
FWHM
) of 94 K. The N500 sample does, however, actually contain both inverse and conventional MCE with
δ
T
FWHM
of 71 K and 24 K, respectively. Interestingly, the changing nitridation temperature during sample preparation allows for significant tailoring of the MCE of a CoFe2/MgO nanocomposite sample. The MCE of the N400 and N500 samples, in particular, spans a wide range of temperatures, including room temperature and cryogenic temperatures, making them notable magnetocaloric materials. Consequently, N400 and N500 samples can be used food-refrigeration and liquefying both nitrogen and helium gases.
Journal Article
The multi peaks of magnetocaloric effect in Ni48Mn39.5Sn9.5Al3 ribbon
The magnetocaloric effect (MCE) of Ni
48
Mn
39.5
Sn
9.5
Al
3
ribbon is simulated using a phenomenological model with possible uses in magnetic refrigeration (MR). In this work, both conventional and inverse MCEs associated with magnetic (ferromagnet-antiferromagnet) and structural (austenite–martensite) phase transitions are theoretically investigated. The results show that three associated peaks of the inverse and conventional MCEs are observed. It is recommended that magnets with triple peak MCE behaviour, such as Ni
48
Mn
39.5
Sn
9.5
Al
3
ribbons, may offer an intriguing MR with a larger temperature-range than conventional refrigerant compounds, particularly Ni
48
Mn
39.5
Sn
9.5
Al
3
ribbons, which are cheap to use in MR. Furthermore, the MCE values of Ni
48
Mn
39.5
Sn
9.5
Al
3
ribbons are significantly higher than those of some magnetocaloric materials from previous studies. Consequently, Ni
48
Mn
39.5
Sn
9.5
Al
3
ribbons are appropriate magnetocaloric magnets for wide temperature range, covering cryogenic and room-temperatures.
Journal Article
Magnetocaloric effect in La1.25Sr0.75MnCoO6
The magnetocaloric properties of La1.25Sr0.75MnCoO6 (LSCM) manganites that were synthesized at 750 and 1,300 °C have been investigated. It is found that magnetic entropy change distribution of the LSCM is much more uniform than that of gadolinium. This feature is desirable for an Ericson-cycle magnetic refrigerator. It is suggested that LSCM can be used in an active magnetic regenerative nitrogen liquefier to cool nitrogen gas from room temperature to 77 K.
Journal Article
Verification of the Phenomenological Model’s Validity for the Conventional and Inverse Magnetocaloric Effects in Ni50Mn34In16
The purpose of this research is to evaluate the validity and reliability of a phenomenological model (PM) for the magnetocaloric effect (MCE) in Ni
50
Mn
34
In
16
. By simulating the MCE of Ni
50
Mn
34
In
16
at temperatures ranging from 190 to 330 K, our work verifies PM for both inverse and conventional MCEs. Interestingly, substantial agreement between measured and simulated magnetic entropy change is obtained across the whole temperature range. Furthermore, there is a satisfactory agreement between the measured and computed absolute values of temperature change (|
∆T
|) of conventional MCE and portion inverse MCE region temperature greater than critical temperature (
T
C
). However, due to the latent heat during the martensitic transition in Ni
50
Mn
34
In
16
, the measured |
∆T
| becomes smaller than the simulated one in the inverse MCE area, which is less than the
T
C
of the AFM state. These findings suggest that PM is a reliable model for exploring both inverse and conventional MCEs in the same sample, saving time and effort in computing and measuring MCE.
Journal Article
Tailoring Magnetocaloric Effect in La0.7Sr0.3MnO3–TiO2
Based on phenomenological model, the effect of TiO2 addition on magnetocaloric effect (MCE) for La0.7Sr0.3MnO3 (LSMO) has been investigated. It is found that at low TiO2 doping decreases slightly magnetocaloric properties. Moreover, LSMO-TiO2 can be tailored to near ambient temperature, which is favorable for magnetic refrigeration that occurs in different temperature ranges. Moreover, MCE of LSMO/TiO2 composites spanning over a broad range of temperature leads to a remarkably wide-working temperature region, which is beneficial for practical applications. These results make the La0.7Sr0.3MnO3–TiO2 samples potential candidates for practical applications.
Journal Article
Investigations on Thermomagnetic Properties of YbFe2As2
A phenomenological model (PM) is applied to simulate magnetocaloric effect (MCE) of YbFe
2
As
2
(YFA) sample. Based on PM, MCE parameters are deduced as the results of simulation for magnetization versus temperature under 5 T magnetic field. The maximum value of magnetic entropy change is 2.55 J/kg K. The values of full-width at half-maximum relative cooling power and refrigerant capacity are 34 K, 87 J/kg, and 62.6 J/kg, respectively. It is recommended that YFA can be used as an effective material of magnetic refrigerator over a temperature range, covering a significant range of temperature between 0 and 50 K. This indicates that YFA is considered as the MCE material functioning at a liquid helium temperature zone.
Journal Article
The Inverse and Conventional Magnetocaloric Effects in Ni0.4Cu0.2Zn0.4Fe2-xDyxO4 Nanoferrites Over an Extraordinary Temperature Range
The magnetocaloric effect (MCE) of Ni0.4Cu0.2Zn0.4Fe2-xDyxO4 (x = 0.02, 0.03, and 0.04) nanoferrites is simulated using a phenomenological model. The analysis indicates that the MCE of Ni0.4Cu0.2Zn0.4Fe2-xDyxO4 nanoferrites is strongly influenced by Dy content in both conventional and inverse MCE. For conventional MCE, the full-width at half-maximum (δTFWHM) has significant values, ranging between 200 K and 258 K for Ni0.4Cu0.2Zn0.4Fe2-xDyxO4 nanoferrites. However, for inverse MCE, δTFWHM ranges between 25 and 55 K. The MCE of the Ni0.4Cu0.2Zn0.4Fe2-xDyxO4 system covers an extensive temperature range and is a particularly interesting prospect for nitrogen and hydrogen liquefaction.
Journal Article
Magnetocaloric Effect for La0.54Sr0.27Gd0.19MnO3 Nanoparticles at Room and Cryogenic Temperatures
The magnetic refrigerator (MR) has gained popularity due to its potential to improve the energy efficiency of refrigeration without the use of unsafe gas, as is the case with traditional gas compression techniques. Magnetocaloric lanthanum manganite investigation, particularly at room and cryogenic temperatures, shows favorable results for the development of MR. Previous thermodynamic models require a significant amount of time and effort to estimate the magnetocaloric effect (MCE). Consequently, we employ the phenomenological model (PM), which is simple and straightforward, requiring fewer parameters than many other modeling methods. We studied the magnetocaloric effect (MCE) of silica-coated La
0.54
Sr
0.27
Gd
0.19
MnO
3
(LSGMO) nanoparticles via PM. According to PM results, MCE parameters were obtained as the consequences of the simulated magnetization of silica-coated LSGMO nanoparticles vs. temperature under 0.1 T a magnetic field. It is revealed that the MCE of silica-coated LSGMO nanoparticles covers a broad range of temperatures between 200 and 330 K. The comparison of MCE parameters for silica-coated LSGMO nanoparticles and some published works shows that silica-coated LSGMO nanoparticles are considerably larger than some of the MCE parameters in these published works. Finally, silica-coated LSGMO nanoparticles are suitable function materials in MR, especially at room and cryogenic temperatures, contributing to efficient MR.
Journal Article
Ferromagnetic solid state refrigeration with tunable magnetic characteristics for green energy magnetic device
The magnetocaloric effect(MCE) of the (Fe
0.5
Cu
0.5
)
60
Zr
40
alloy has been investigated by phenomenological model, estimating magnetic entropy change (∆S
M
) and heat capacity change. The results indicate that MCE of (Fe
0.5
Cu
0.5
)
60
Zr
40
alloy can be controlled and tuned by several magnetic fields. Furthermore, the study of ∆S
M
curves predicts how to expand the temperature range for exploiting (Fe
0.5
Cu
0.5
)
60
Zr
40
in magnetic refrigeration. ∆S
M
reaches a peak of about 0.5 J/Kg K at 112 K with δT
FWHM
= 227 K and RCP = 102 J/Kg under 5 T applied field variation. (Fe
0.5
Cu
0.5
)
60
Zr
40
alloy has a potential application for magnetic refrigerants over a wide temperature range, especially its high electrical resistivity leads to decreased eddy current losses, covering a significant range of temperature between 0 K and room temperature. Therefore, these advantages make (Fe
0.5
Cu
0.5
)
60
Zr
40
alloy potentially practical for efficient cooling devices.
Journal Article