摘要
本文基于磁热效应的绿色磁制冷技术,并以Ni-Mn-Ga Heusler合金为对象,系统地探索其作为磁制冷工质的潜力.为阐明富Mn成分对合金磁性与磁热性能的调控机制,采用第一性原理计算与蒙特卡罗模拟相结合的多尺度方法,重点分析Mn原子分别占据Ni与Ga位时,对合金微观结构、原子磁矩、交换作用及宏观磁热行为的影响.结果表明, Mn占位方式对磁性能具有关键调控作用:Mn占据Ni位会降低总磁矩与居里温度,并减小磁熵变;而Mn占据Ga位则显著提升总磁矩与磁熵变,其中Ni_(8)Mn_(7)Ga_(1)合金在2 T磁场下的最大磁熵变高达2.32 J·kg^(-1)·K^(-1),远高于化学计量比Ni_(8)Mn_(4)Ga_(4)合金.态密度与交换作用分析进一步表明, Mn含量变化可调控其在费米能级附近的电子结构,优化轨道杂化与铁磁交换作用,影响磁相变行为.临界指数分析显示合金中磁相互作用具有长程特性,并随成分变化趋近于平均场行为.本工作从微观层面建立了“成分-结构-磁性-磁热性能”之间的构效关系,为设计高性能、低滞后磁制冷材料提供了理论依据.
This work investigates the magnetocaloric effect-based green magnetic refrigeration technology,with a focus on Ni-Mn-Ga Heusler alloy as a promising magnetic refrigerant candidate.To elucidate the role of Mnrich composition in regulating the magnetic and magnetocaloric properties,a multi-scale computational approach integrating first-principles calculations and Monte Carlo simulations is adopted.This method enables a detailed analysis of how Mn atoms occupying Ni and Ga sites influence the microstructure,atomic magnetic moments,exchange interactions,and macroscopic magnetocaloric response of the alloy.The results indicate that Mn site occupancy critically affects the magnetic performance:the occupation of Ni sites reduces the total magnetic moment and Curie temperature,thereby reducing the magnetic entropy change;in contrast,Mn occupying Ga sites significantly enhances both the total magnetic moment and the magnetic entropy change.Notably,the Ni_(8)Mn_(7)Ga_(1) alloy achieves a maximum magnetic entropy change of 2.32 J·kg^(-1)·K^(-1) under a 2 T magnetic field,which significantly exceeds that of the stoichiometric Ni_(8)Mn_(4)Ga_(4) alloy.Further electronic structure analysis reveals that Mn content variation modulates the density of states near the Fermi level and optimizes orbital hybridization and ferromagnetic exchange interactions,thus adjusting the magnetic phase transition behavior.Critical exponent analysis confirms that the magnetic interactions are inherently long-range and tend toward mean-field behavior with compositional changes.By establishing a clear“composition-structure-magnetism-magnetocaloric performance”relationship on an atomic scale,this work provides theoretical foundations for designing high-performance,low-hysteresis magnetic refrigeration materials.
作者
汪波
张玉芬
邵辉
张泽宇
胡勇
WANG Bo;ZHANG Yufen;SHAO Hui;ZHANG Zeyu;HU Yong(Office of Liaoning Higher and Secondary Education Enrollment Examination Committee,Shenyang 110034,China;Huludao Experimental High School,Huludao 125000,China;Shenyang No.4 Middle School,Shenyang 110023,China;Department of Physics,College of Sciences,Northeastern University,Shenyang 110819,China;Foshan Graduate School of Innovation,Northeastern University,Foshan 528311,China)
出处
《物理学报》
北大核心
2026年第1期348-361,共14页
Acta Physica Sinica
基金
国家自然科学基金(批准号:U22A20117)
广东省基础与应用基础研究基金(批准号:2023A1515140171)资助的课题。
关键词
NI-MN-GA合金
磁热效应
二级磁相变
蒙特卡罗模拟
Ni-Mn-Ga alloy
magnetocaloric effect
second-order magnetic phase transition
Monte Carlo simulation
