Cr对Mn_(5)Ge_(3)结构和磁性能的调控  

The Regulation of Chromium Doping on the Structure and Magnetic Properties of Mn_(5)Ge_(3)

作　　者：朱瑞恒 杨通晗 梁建烈[1] 李康颖 贾一凡 宁伟棋 ZHU Ruiheng;YANG Tonghan;LIANG Jianlie;LI Kangying;JIA Yifan;NING Weiqi(Guangxi Key Laboratory of Advanced Structural Materials and Carbon Neutralization,School of Materials and Environment,Guangxi Minzu University,Guangxi Colleges and Universities Key Laboratory of Eco-friendly Materials and Ecological Restoration,Nanning,Guangxi 530105,China)

机构地区：[1]广西民族大学材料与环境学院,广西先进结构材料与碳中和重点实验室,广西高校环境友好材料及生态修复重点实验室,南宁530105

出　　处：《中国无机分析化学》2025年第4期563-575,共13页Chinese Journal of Inorganic Analytical Chemistry

基　　金：广西自然科学基金面上项目(2018GXNSFAA138043);广西高校中青年教师科研基础能力提升项目(2023KY0165);广西民族大学引进人才科研启动项目(2022KJQD39)。

摘　　要：Mn_(5)Ge_(3)因具有较大磁热效应、磁相变无热滞、居里温度在室温附近等优点,被视为潜在的室温磁制冷材料。但其仍存在制冷温区窄等问题。用Cr对Mn_(5)Ge_(3)的晶体结构、电子结构和磁性能进行调控,利用Rietveld结构精修方法对Mn_(5-x)Cr_(x)Ge_(3)的晶体结构进行研究。结果显示,所有样品均为Mn_(5)Si_(3)型结构,空间群为P63/mcm,Cr的掺杂使化合物的晶胞收缩。当Cr含量由x=0升至x=0.15时,其居里温度从301 K降低至285 K。在17 kOe磁场变化下,Mn_(5-x)Cr_(x)Ge_(3)的最大磁熵变由3.27 J/(kg·K)降至2.91 J/(kg·K),制冷温区由28 K升至30 K,制冷能力先上升后下降,在x=0.1处达最大,最大值为92.7 J/K。电荷密度分析表明,随着Cr含量的增加,Mn原子周围的电子密度明显下降,说明Cr的掺杂导致化合物中Mn-Mn之间的相互作用减弱,最终导致化合物磁性交换作用降低,揭示了Cr对Mn_(5)Ge_(3)磁性能的调控机制,为探索高性能磁制冷材料提供了新的视角和策略。Since the advantages of large magnetocaloric effect,no thermal hysteresis in magnetic phase transition,and Curie temperature near room temperature,Mn_(5)Ge_(3) is regarded as a potential room-temperature magnetic refrigeration material.However,the narrow refrigeration temperature range and other issues hinder its application.The Cr was used to tune the crystal structure,electronic structure and magnetic properties of Mn_(5)Ge_(3) in this study.The Rietveld structure refinement method was used to investigate the crystal structure of Mn_(5-x)Cr_(x)Ge_(3).The results showed that all samples had a Mn_(5)Si_(3)-type structure with a space group of P63/mcm,and the doping of Cr shrank the unit cell of the compound.When the Cr content increased from x=0 to x=0.15,its Curie temperature decreased from 301 K to 285 K.Under a 17 kOe magnetic field,the maximum magnetic entropy change of Mn_(5-x)Cr_(x)Ge_(3) decreased from 3.27 J/(kg·K)to 2.91 J/(kg·K),the refrigeration temperature range increased from 28 K to 30 K,and the relative refrigeration power increased first and then decreased,reaching a maximum of 92.7 J/K at x=0.1.Charge density analysis showed that with the doping of Cr,the electron density around Mn atoms decreased significantly,indicating that the interaction between Mn-Mn in the compound was weaken,ultimately leading to a decrease in the magnetic exchange interaction of the compound.This study reveals the tunable mechanism of Cr on the magnetic properties of Mn_(5)Ge_(3),providing a new perspective and strategy for exploring high-performance magnetic refrigeration materials.

关 键 词：Mn_(5-x)Cr_(x)Ge_(3) 晶体结构 磁性能 电荷密度 

分 类 号：O65[理学—分析化学]