JOURNAL OF ALLOYS AND COMPOUNDS
·
2023
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IF 6.2
Sujuan Wang,Qing Luo,Xiaohua Luo,Shengcan Ma,Changcai Chen,Fei Gao,Bodong Lv,Rui Zhong,Weijun Ren,Zhenchen Zhong
The effects of Si and Cu doping on crystal structures, magnetism , and the magnetocaloric effect of EuAl 4 have been investigated. EuAl 4 , EuAl 3.35 Si 0.65 , and EuAl 3.82 Cu 0.18 single crystals grown by the Al flux method are isotypic and crystallize in BaAl 4 -type structure with space group I 4 /mmm . Compared to the pristine compound EuAl 4 , the lattice parameter a keeps almost unchanged and c decreases obviously by Si doping, while a decreases and c increases upon Cu-substitution. These irregular changes in the lattice parameters may contribute to the electronegativity difference between Si and Cu. Cu and Si doping enhances the ferromagnetic interaction, and the direction of easy magnetization changes from the ab plane to the c axis upon the Cu-substitution. Multiple-step metamagnetic transitions are still observed in EuAl 3.35 Si 0.65 as applying the magnetic field along the c axis, while EuAl 3.82 Cu 0.18 shows ferromagnetic behavior along the ab plane and c axis. As a consequence, the low-field magnetocaloric effect is significantly enhanced. The maximum magnetic entropy change under a field change of 20 kOe increases from − 8.4 J/kg K for EuAl 4 to − 12.9 J/kg K for EuAl 3.35 Si 0.65 and − 15.9 J/kg K for EuAl 3.82 Cu 0.18 . The corresponding values of refrigerating capacity are 67, 140, and 147 J/kg, respectively. The remarkable magnetocaloric performances suggest that the Cu-doped EuAl 4 compound is an excellent candidate material for low-temperature magnetic refrigeration.
研究领域:
凝聚态物理
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材料科学
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磁学
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低温物理
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功能材料
✓ 已验证
DOI
高影响因子
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2022
·Vol. 24
·期 36
·21872-21885
·
IF 3.945
Zhiwei Gong,Wei Xu,N. A. Liedienov,D. S. Butenko,I. V. Zatovsky,I. A. Gural'skiy,Ziyu Wei,Quanjun Li,Bingbing Liu,Yu. A. Batman,A. V. Pashchenko,G. G. Levchenko
Prospects for the use of manganites in various areas of modern technologies require comprehensive studies of their physical and chemical properties. La0.9Mn1.1O3 (LMO) ceramics have been synthesized at an annealing temperature tann of 1150 °C with further post-annealing at 1250, 1350, and 1450 °C. As tann increases, the structure symmetry changes, and both the crystallite size and chemical defects increase. The post-annealing, on one hand, leads to a dramatic reduction of the magnetocaloric effect (MCE) |−ΔSmaxM| from 3.50 to 0.75 J (kg K)−1 at 2 T and a Curie temperature TC from 227 to 113 K with increasing tann. On the other hand, an external hydrostatic high-pressure P works oppositely enhancing ferromagnetic interactions. The saturation of −ΔSmaxM and TC is already achieved at a relatively low P of ≈ 0.4 GPa. LMO-1150 exhibits the best magnetocaloric characteristics compared with other studied samples. Moreover, the electrochemical characteristics of the LMO materials as electrocatalysts for overall water splitting (OER process) and features of their transformation in different 0.5 M K2SO4, 0.5 M K2HPO4, and 0.1 M K2B4O7 electrolytes have been studied thoroughly. After electrocatalysis of LMO, the magnetization M decreases and TC remains, which makes it possible to control the depletion of electrodes and predict their working time based on the magnetic measurements. All samples show the best OER activity in the 0.5 M K2HPO4 media. The obtained results demonstrate the ways for controlling the MCE of LMO under changing internal and external conditions, and an evaluation of the possibilities for their OER applications in electrocatalysts.
研究领域:
材料科学
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凝聚态物理
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电化学
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功能陶瓷
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磁学
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能源材料
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催化化学
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2022
·
IF 6.371
Huicai Xie,Quanyi Liu,Xiaohua Luo,Shengcan Ma,Xinqiang Gao,Zhenxing Li,Zhaojun Mo,Jun Shen
For more practical applications, research on magnetic refrigeration has been gradually focused on developing refrigerants with large magnetocaloric effect (MCE) under low magnetic fields (≤2 T). EuTiO 3 exhibits considerable low-field MCE near ordering temperature, meanwhile the magnetic switch from antiferromagnetic to ferromagnetic (AFM-FM) in it provides the feasibility of improving the magnetocaloric performance. In this study, a series of Eu(Ti,Nb,M)O 3 (M=Cu or Zn) compounds were synthesized, and the crystal structure, magnetic properties together with cryogenic MCEs were investigated in detail. The co-substitution contributes to an FM coupling domination in all the compounds. Besides, significantly enhanced and giant low-field MCEs were detected in these compounds. Under the field change of 1 T, all the samples possess remarkable magnetic entropy change (>15 J·kg -1 ·K -1 ) around 5 K without hysteresis. The corresponding refrigerating capacities are calculated to be 68.0, 72.6, 76.0, and 69.6 J·kg -1 , respectively, exhibiting an increase of 149–178% than EuTiO 3 . The outstanding magnetocaloric performances make the Eu(Ti,Nb,M)O 3 (M=Cu or Zn) compounds competitive candidates for cryogenic magnetic refrigeration.
研究领域:
材料科学
·
凝聚态物理
·
功能材料
·
低温工程
·
磁学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）