摘要
研究了金属化合物LaFe_(11.5)Al_(1.5)H_x(x=0,0.12,0.6,1.3),LaFe_(11.5)Al_(1.5)B_y(y=0.1,0.2,0.3)和LaFe_(11.5)Al_(1.5)C_z(z=0.1,0.2,0.3,0.4,0.5)的磁性、结构和磁热效应.金属化合物样品均形成了良好的NaZn_(13)型单相结构.基于固相-气相反应或者固相-固相反应引入间隙H,B,C原子后,磁性基态从反铁磁态变为铁磁态,饱和磁化强度(M_s)和居里温度(T_c)均呈升高趋势.值得注意的是:随着B和C含量的增加,化合物的相变性质由弱一级相变过渡至二级相变;而随着H含量的增加,相变性质却从二级相变过渡至弱一级相变.同时,化合物LaFe_(11.5)Al_(1.5)H_x,LaFe_(11.5)Al_(1.5)B_y和LaFe_(11.5)Al_(1.5)C_z均呈现出相当大的磁熵变.在0—5 T的外磁场作用下,LaFe_(11.5)Al_(1.5)H_(1.3),LaFe_(11.5)Al_(1.5)B_(0.1)和LaFe_(11.5)Al_(1.5)C_(0.2)的最大磁熵变分别达到12.3,9.6和10.8 J/kg·K.此外,在0—5 T的外磁场作用下,LaFe_(11.5)Al_(1.5)H_(0.6)的制冷能力达到259.2 J/kg,LaFe_(11.5)Al_(1.5)B_(0.1)的制冷能力达到116.4 J/kg,而LaFe_(11.5)Al_(1.5)C_(0.1)的制冷能力达到230.4 J/kg.
Magnetic refrigeration materials based on magnetocaloric effect （MCE） attract wide attention. In the past decades, magnetic materials with MCE have been extensively studied due to their enormous potential applications in magnetic refrigeration fields. Among these materials, La（Fe, Al）13 compound is perceived to be one of the promising candidates as high-performance magnetic refrigerant because of its giant magnetic entropy change, tunable Curie temperature, low cost and toxin-flee. For LaFe13_~Alxcompounds, previous studies showed that the Tc can increase by substituting Co for Fe, which leads to the value of maximum magnetic entropy change （--ASM） decreasing. In addition, the interstitial atom （N, H, C and B） can cause the lattice to expand, which shifts the anti-ferromagnetic （AFM） ground state to the ferromagnetic （FM） state. The Tc increases with doping the interstitial atoms, accompanied by a remarkable change in the magnetic properties related to the magneto-volume effect. In this paper, the magnetic properties and the magnetocaloric effects of LaFell.5All.hHx （x= 0, 0.12, 0.6 and 1.3）, LaFell.5All.hBy （y = 0.1, 0.2 and 0.3） and LaFe11.5All.5Cz （z = 0.1, 0.2, 0.3, 0.4 and 0.5） intermetallic compounds are studied. The H, B or C atoms are inserted into the LaFe11.5Al1.5 compounds by gas-solid or solid-solid reaction. All the compounds crystallize into the cubic NaZn13-type structure. The magnetic ground state changes from the AFM to the FM state due to the introduction of interstitial atoms. Unlike the patent compound LaFell.5All.5, all of the hydrides, borides and carbides display a typical FM state, which easily reach saturation under a magnetic field of 1 T. In addition, the saturation magnetization （Ms） slightly increases and the Curie temperature （Tc） significantly is enhanced with increasing the interstitial atom （H, B or C） content. It is attractive that the magnetic transition changes from the second-order to the weakly first-order with increasing hydrogen content, which is in contrast with the magnetic transition from the weakly first-order to the second-order with increasing boron or carbon content. All the compounds of LaFell.hAll.5 hydrides, borides and carbides exhibit a considerable magnetic entropy change. The values of maximum magnetic entropy change （--ASM） reach 12.3 J/kg.K for LaFe11.5Al1.hH1.3, 9.6 J/kg.K for LaFell.hAll.hB0.1 and 10.8 J/kg.K for LaFe11.5All.5C0.2 under a magnetic field change of 0-5 T, respectively. And the values of refrigerant capacity （RC） reach 259.2 J/kg for LaFell.hAll.hH0.6, 116.4 J/kg for LaFe11.5All.aB0.1, and 230.4 J/kg for LaFell.hAll.aC0.1 under a magnetic field change of 0-5 T, respectively, indicating that LaFell.hAll.hH0.6 compound is a promising candidate for magnetic refrigerants.
作者
杨静洁
赵金良
许磊
张红国
岳明
刘丹敏
蒋毅坚
Yang Jing-Jie1） Zhao Jin-Liang1）t Xu 2） 3）(Institute Liu Dan-Min3） Lei1）2） Zhang Hong-Guo2） Yue Ming2） Jiang Yi-Jian4） 1） （College of Applied Sciences, Beijing University of Technology, Beijing 100124, China） （College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China） of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100124, China） 4） （Institute of Laser Engineering, Beijing University of Technology, Beijing 100124, China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2018年第7期234-241,共8页
Acta Physica Sinica
基金
国家自然科学基金(批准号:51401002
51171003)
北京市自然科学基金(批准号:1112005)
新金属材料国家重点实验室开放基金(批准号:2015-ZD)资助的课题~~
