Iron Oxide-based Magnetic Nanoparticles for High Temperature Span Magnetocaloric Applications

2014 ◽  
Vol 1708 ◽  
Author(s):  
V. Chaudhary ◽  
R. V. Ramanujan
Keyword(s):  
High Temperature ◽  
Transition Temperature ◽  
Magnetic Nanoparticles ◽  
Room Temperature ◽  
Magnetic Entropy Change ◽  
Average Crystallite Size ◽  
Entropy Change ◽  
Superparamagnetic Nanoparticles ◽  
Cooling Power ◽  
Magnetic Entropy

ABSTRACTThe magnetocaloric effect of chemically synthesized Mn0.3Zn0.7Fe2O4 superparamagnetic nanoparticles with average crystallite size of 11 nm is reported. The magnitude of the magnetic entropy change (ΔSM), calculated from magnetization isotherms in the temperature range of 30 K to 400 K, increases from - 0.16 J-kg-1K-1 for a field of 1 T to - 0.88 J-kg-1K-1 for 5 T at room temperature. Our results indicate that ΔSM values are much higher than primarily reported values for this class of nanoparticles. ΔSM is not limited to the ferromagnetic-paramagnetic transition temperature; instead, it occurs over a broad range of temperatures, resulting in high relative cooling power.

Refrigerant Capacity and Magnetocaloric Effect on LaFe11.1Co0.8Si1.1BX Alloys

2011 ◽  
Vol 84-85 ◽  
pp. 667-670
Author(s):  
Guo Qiu Xie
Keyword(s):  
Magnetocaloric Effect ◽  
Room Temperature ◽  
Magnetic Entropy Change ◽  
Entropy Change ◽  
Magnetic Entropy ◽  
Field Change ◽  
Refrigerant Capacity ◽  
Structure Phase ◽  
Magnetic Field Change ◽  
Cubic Structure

In this paper, we report on the structure, magnetic properties and magnetocaloric effect in NaZn13-type LaFe11.1Co0.8Si1.1Bxalloys close to room temperature. The stable NaZn13cubic structure phase (space group isFm-3c) can easily obtained by annealing at 1080 °C for 225 hours. The maximal values of magnetic entropy change for LaFe11.1Co0.8Si1.1Bx(x=0.2, 0.25) were found to be 5.3 and 5.9 J/kg K at Curie temperature for a magnetic field change in 0-1.5 T, respectively. The calculated refrigerant capacity for a field change in 0–1.5 T is about 147 and 107 J/kg K, for LaFe11.1Co0.8Si1.1B0.2and LaFe11.1Co0.8Si1.1B0.25respectively, which is as larger as those of Gd(99.3%) alloy

scholarly journals Extremely Large Magnetic Entropy Change of MnAs1-xSbx near Room Temperature

2002 ◽  
Vol 43 (1) ◽  
pp. 73-77 ◽  
Author(s):  
Hirofumi Wada ◽  
Kentaro Taniguchi ◽  
Yuji Tanabe
Keyword(s):  
Room Temperature ◽  
Magnetic Entropy Change ◽  
Entropy Change ◽  
Magnetic Entropy

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

2009 ◽  
Vol 154 ◽  
pp. 163-168 ◽  
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.

Room-temperature magnetic entropy change in La0.7 Sr0.3 Mn1-x Mx O3 (M = Al, Ti)

2007 ◽  
Vol 244 (12) ◽  
pp. 4570-4573 ◽  
Author(s):  
N. V. Dai ◽  
D. V. Son ◽  
S. C. Yu ◽  
L. V. Bau ◽  
L. V. Hong ◽  
...  
Keyword(s):  
Room Temperature ◽  
Magnetic Entropy Change ◽  
Entropy Change ◽  
Magnetic Entropy

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.

scholarly journals Phase formation and magnetocaloric effect in (Pr,Nd)-Fe alloys prepared by rapidly quenched method

2018 ◽  
Vol 185 ◽  
pp. 05002
Author(s):  
Dan Nguyen ◽  
Ha Nguyen ◽  
An Nguyen ◽  
Yen Nguyen ◽  
Thanh Pham ◽  
...  
Keyword(s):  
Temperature Region ◽  
Melt Spinning ◽  
Room Temperature ◽  
Magnetic Entropy Change ◽  
Entropy Change ◽  
Magnetic Entropy ◽  
Annealing Conditions ◽  
Different Temperatures ◽  
Fe Alloys ◽  
Bulk Alloys

In this work, Pr2-xNdxFe17 (x = 0 - 2) ribbons with thickness of about 15 μm were prepared by melt-spinning method. The alloy ribbons were then annealed at different temperatures (900 - 1100°C) for various time (0.25 - 2 h). The formation of the (Pr,Nd)2Fe17 (2:17) crystalline phase in the alloys strongly depends on the Pr/Nd ratio and annealing conditions. Annealing time for the completed formation of the 2:17 phase in the rapidly quenched ribbons is greatly reduced in comparison with that of bulk alloys. Curie temperature, TC, of the alloys can be controlled in room temperature region by changing Pr/Nd ratio. Maximum magnetic entropy change (|ΔSm|max) and full width at haft the maximum peak (FWHM) of the magnetic entropy change of the alloys were respectively found to be larger than 1.5 J.kg−1K−1 and 40 K in room temperature region with magetic field change ΔH = 12 kOe.

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