scholarly journals Giant barocaloric effect in hexagonal Ni2In-type Mn-Co-Ge-In compounds around room temperature

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Rong-Rong Wu ◽  
Li-Fu Bao ◽  
Feng-Xia Hu ◽  
Hui Wu ◽  
Qing-Zhen Huang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Room Temperature ◽  
Superconducting Magnets ◽  
Entropy Change ◽  
Lattice Expansion ◽  
Moderate Pressure ◽  
Gas Compression ◽  
Lower Temperature ◽  
Giant Magnetocaloric Effect ◽  
Magnetostructural Transformation

Abstract The most widespread cooling techniques based on gas compression/expansion encounter environmental problems. Thus, tremendous effort has been dedicated to develop alternative cooling technique and search for solid state materials that show large caloric effects. An application of pressure to a material can cause a change in temperature, which is called the barocaloric effect. Here we report the giant barocaloric effect in a hexagonal Ni2In-type MnCoGe0.99In0.01 compound involving magnetostructural transformation, T mstr, which is accompanied with a big difference in the internal energy due to a great negative lattice expansion(ΔV/V ~ 3.9%). High resolution neutron diffraction experiments reveal that the hydrostatic pressure can push the T mstr to a lower temperature at a rate of 7.7 K/kbar, resulting in a giant barocaloric effect. The entropy change under a moderate pressure of 3 kbar reaches 52 Jkg−1K−1, which exceeds that of most materials, including the reported giant magnetocaloric effect driven by 5 T magnetic field that is available only by superconducting magnets.

scholarly journals A Faraday Anomalous Dispersion Optical Filter Based on Rubidium Hollow-Cathode Lamp

2020 ◽  
Vol 10 (20) ◽  
pp. 7075
Author(s):  
Liang Shen ◽  
Rui Ma ◽  
Longfei Yin ◽  
Bin Luo ◽  
Duo Pan ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Hollow Cathode ◽  
Room Temperature ◽  
Saturated Vapor ◽  
Optical Filter ◽  
Optical Filters ◽  
Anomalous Dispersion ◽  
Narrow Linewidth ◽  
Hollow Cathode Lamp ◽  
Lower Temperature

Using a hollow-cathode lamp (HCL) to build a Faraday anomalous dispersion optical filter (FADOF) is a new method to realize narrow linewidth optical filters. In contrast to other atomic optical filters based on saturated vapors, which work at a relatively high temperature to maintain the atomic density, the HCL device using sputtered particles can work at a much lower temperature. In this work, a rubidium HCL-based FADOF (HCL-FADOF) working at 780 nm is established and carefully tested. With 20 mm cathode length, the transmittance can reach 29% under 18 mA discharge current and 260 G magnetic field at room temperature, which is equivalent to the performance of a saturated vapor-based FADOF (VC-FADOF) at more than 60 ∘C. This work provides a direct comparison of the performance of the HCL-FADOF and the VC-FADOF, which is of great benefit to further studies of atomic filters at normal temperature.

Performance Analysis of the Regenerative Brayton Refrigeration Cycle Using Gd0.94Er0.06 as the Working Substance

2013 ◽  
Vol 631-632 ◽  
pp. 318-321
Author(s):  
Wang Yuan ◽  
Gildas Diguet ◽  
Guo Xing Lin ◽  
Jin Can Chen
Keyword(s):  
Magnetic Field ◽  
Room Temperature ◽  
Entropy Change ◽  
Coefficient Of Performance ◽  
Refrigeration Cycle ◽  
Analysis Method ◽  
Magnetic Field Change ◽  
Effects Of Temperature ◽  
Brayton Refrigeration Cycle ◽  
Set Up

Based on the experimental data of entropy change varying with temperature, the regenerative Brayton refrigeration cycle using Gd0.94Er0.06 as the working substance is set up for magnetic field changes with 0-1T and 0-2T. By using thermodynamic analysis method, some parameters such as the non-perfect regeneration, net cooling quantity, coefficient of performance (COP), and so on, are analyzed and calculated. The effects of temperature of the heat reservoir, regeneration and external magnetic field are also discussed. The results obtained in the present paper show that the refrigeration cycle operating in TC=T0, TH= T0+7K and 0-2T magnetic field change has not only maximum cooling quantity but also maximum COP in all the established magnetic refrigeration cycles, and can provide some new guide for the optimal design of real room-temperature magnetic refrigerators.

Giant Magnetocaloric Effect in the Region of Magnetic Phase Transition in Mn (As,Sb) Compounds

2012 ◽  
Vol 190 ◽  
pp. 343-346 ◽  
Author(s):  
N.Yu. Pankratov ◽  
V.I. Mitsiuk ◽  
A.I. Krokhotin ◽  
A.I. Smarzhevskaya ◽  
G.A. Govor ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Magnetic Properties ◽  
Room Temperature ◽  
Magnetic Phase ◽  
Small Concentration ◽  
Maximum Value ◽  
Giant Magnetocaloric Effect ◽  
Magnetic Filed ◽  
Direct Investigation

The MCE in MnAs and doped Mn (As,Sb) compounds with low concentration of Sb has been studied by direct investigation. It was shown that for MnAs the maximum value of MCE is ΔT = 0.28 K on heating (at 308 K) and ΔT = 0.88 K on cooling (at T = 306 K) in magnetic filed 12.5 kOe. In doped Mn (As,Sb) compounds the temperature dependence of MCE is similar to MnAs. All investigated compounds demonstrate a strong temperature and field hysteresis of magnetic properties in magnetic field less than 40 kOe. It was established that a small concentration of Sb leads to decrease of MCE hysteresis and preserves the phase transition at room temperature region.

scholarly journals High-efficiency magnetic refrigeration using holmium

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Noriki Terada ◽  
Hiroaki Mamiya
Keyword(s):  
Magnetic Field ◽  
Permanent Magnets ◽  
High Efficiency ◽  
Entropy Change ◽  
Superconducting Magnet ◽  
Magnetic Refrigeration ◽  
Suitable Alternative ◽  
Small Magnetic Field ◽  
Gas Compression ◽  
Order Of Magnitude

AbstractMagnetic refrigeration (MR) is a method of cooling matter using a magnetic field. Traditionally, it has been studied for use in refrigeration near room temperature; however, recently MR research has also focused on a target temperature as low as 20 K for hydrogen liquefaction. Most research to date has employed high magnetic fields (at least 5 T) to obtain a large entropy change, which requires a superconducting magnet and, therefore, incurs a large energy cost. Here we propose an alternative highly efficient cooling technique in which small magnetic field changes, Δμ0H ≤ 0.4 T, can obtain a cooling efficiency of −ΔSM/Δμ0H = 32 J kg−1K−1T−1, which is one order of magnitude higher than what has been achieved using typical magnetocaloric materials. Our method uses holmium, which exhibits a steep magnetization change with varying temperature and magnetic field. The proposed technique can be implemented using permanent magnets, making it a suitable alternative to conventional gas compression–based cooling for hydrogen liquefaction.

The Influence of the Purity of Gd on the Magnetocaloric Effect in Gd5Si2-XGe2-XZn2x Alloys

2011 ◽  
Vol 685 ◽  
pp. 311-315
Author(s):  
Zhi Zeng ◽  
Xue Zhen Wang ◽  
Jian Huang ◽  
Jie Xiang ◽  
Xue Ling Hou
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetocaloric Effect ◽  
Curie Point ◽  
Magnetic Entropy Change ◽  
Entropy Change ◽  
Magnetic Entropy ◽  
Field Change ◽  
Magnetic Field Change ◽  
Giant Magnetocaloric Effect

Gd5Si2Ge2-based alloys can exhibit a giant magnetocaloric effect (GMCE) which gives them the potential use in the cooling technologies[1].Through this studies, it can be found that the purity of Gd had a great impact on the magnetocaloric effect in Gd5Si2-xGe2-xZn2x alloys. When 3N Gd used and 2x=0.01, Gd5Si2-xGe2-xZn2x around the curie point of 280k get the maximum magnetic entropy change of 14.0 J/(Kg.K) under the external magnetic field change from 0 to 1T, but when 2N Gd used and 2x=0.05, Gd5Si2-xGe2-xZn2x around the curie point of 284.2k under the external magnetic field change 1T get the maximum magnetic entropy change 6.65 J/(Kg.K).

scholarly journals Magnetocaloric materials with ultra-small magnetic nanoparticles working at room temperature

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
M. R. Dudek ◽  
K. K. Dudek ◽  
W. Wolak ◽  
K. W. Wojciechowski ◽  
J. N. Grima
Keyword(s):  
Magnetic Field ◽  
Magnetic Nanoparticles ◽  
Room Temperature ◽  
Mean Field ◽  
Volume Ratio ◽  
Entropy Change ◽  
Local Cooling ◽  
The Mean ◽  
Magnetocaloric Materials ◽  
Film Form

AbstractThrough the use of the Monte Carlo simulations utilising the mean-field approach, we show that a dense assembly of separated ultra-small magnetic nanoparticles embedded into a non-magnetic deformable matrix can be characterized by a large isothermal magnetic entropy change even upon applying a weak magnetic field with values much smaller than one Tesla. We also show that such entropy change may be very significant in the vicinity of the room temperature which effect normally requires an application of a strong external magnetic field. The deformable matrix chosen in this work as a host for magnetic nanoparticles adopts a thin film form with a large surface area to volume ratio. This in turn in combination with a strong magneto-volume coupling exhibited by this material allows us to show its suitability to be used in the case of a variety of applications utilising local cooling/heating such as future magnetic refrigerants.

Room Temperature Magnetocaloric Effect of the Cox(MnSb)1-x Compounds

2013 ◽  
Vol 683 ◽  
pp. 56-59 ◽  
Author(s):  
Jian Hua Lin ◽  
Shan Dong Li ◽  
Li Li Wang ◽  
Jie Qiu ◽  
Zhi Yi Cai ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetocaloric Effect ◽  
Room Temperature ◽  
Magnetic Entropy Change ◽  
Magnetic Hysteresis ◽  
Entropy Change ◽  
Magnetic Entropy ◽  
Thermal Lag ◽  
Magnetocaloric Materials ◽  
Curie Temperature Tc

The room-temperature magnetocaloric effect (MCE) of Cox(MnSb)1-x (x=0.07, 0.15, 0.24) alloys has been investigated. It is revealed that the Curie temperature TC and the magnetic entropy change ΔSM are sensitive to the Co content x. When x=0.15, the MCE of Co0.15(MnSb)0.85 alloy is optimal with ΔSM=1.8 J/kg.K at 324 K under an applied magnetic field of 3 T. A second-order phase transformation occurs around TC, and the magnetic hysteresis loss thermal lag is negligible. These features demonstrate that Co0.15(MnSb)0.85 alloy is a promising room-temperature magnetocaloric materials.

scholarly journals Practical Synthesis of 2-Iodosobenzoic Acid (IBA) without Contamination by Hazardous 2-Iodoxybenzoic Acid (IBX) under Mild Conditions

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 1897
Author(s):  
Hideyasu China ◽  
Nami Kageyama ◽  
Hotaka Yatabe ◽  
Naoko Takenaga ◽  
Toshifumi Dohi
Keyword(s):  
Aqueous Solution ◽  
Room Temperature ◽  
Practical Method ◽  
Hypervalent Iodine ◽  
Mild Conditions ◽  
Sequential Procedures ◽  
Iodine Compounds ◽  
Practical Synthesis ◽  
Iodosobenzoic Acid ◽  
Lower Temperature

We report a convenient and practical method for the preparation of nonexplosive cyclic hypervalent iodine(III) oxidants as efficient organocatalysts and reagents for various reactions using Oxone® in aqueous solution under mild conditions at room temperature. The thus obtained 2-iodosobenzoic acids (IBAs) could be used as precursors of other cyclic organoiodine(III) derivatives by the solvolytic derivatization of the hydroxy group under mild conditions of 80 °C or lower temperature. These sequential procedures are highly reliable to selectively afford cyclic hypervalent iodine compounds in excellent yields without contamination by hazardous pentavalent iodine(III) compound.

scholarly journals All organic multiferroic magnetoelectric complexes with strong interfacial spin-dipole interaction

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Yuying Yang ◽  
Zhiyan Chen ◽  
Xiangqian Lu ◽  
Xiaotao Hao ◽  
Wei Qin
Keyword(s):  
Magnetic Field ◽  
Light Intensity ◽  
Room Temperature ◽  
Incident Light ◽  
Dipole Interaction ◽  
Interfacial Interaction ◽  
Magnetoelectric Coupling ◽  
Incident Light Intensity ◽  
Organic Ferromagnets ◽  
Magnetoelectric Coefficient

AbstractThe organic magnetoelectric complexes are beneficial for the development on flexible magnetoelectric devices in the future. In this work, we fabricated all organic multiferroic ferromagnetic/ferroelectric complexes to study magnetoelectric coupling at room temperature. Under the stimulus of external magnetic field, the localization of charge inside organic ferromagnets will be enhanced to affect spin–dipole interaction at organic multiferroic interfaces, where overall ferroelectric polarization is tuned to present an organic magnetoelectric coupling. Moreover, the magnetoelectric coupling of the organic ferromagnetic/ferroelectric complex is tightly dependent on incident light intensity. Decreasing light intensity, the dominated interfacial interaction will switch from spin–dipole to dipole–dipole interaction, which leads to the magnetoelectric coefficient changing from positive to negative in organic multiferroic magnetoelectric complexes.

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