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中国物理学会期刊

间隙原子H,B,C对LaFe11.5Al1.5化合物磁性和磁热效应的影响

CSTR: 32037.14.aps.67.20172250

Influences of interstitial atoms H, B and C on magnetic properties and magnetocaloric effect in LaFe11.5Al1.5 compound

CSTR: 32037.14.aps.67.20172250
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  • 研究了金属化合物LaFe11.5Al1.5Hx (x=0,0.12,0.6,1.3),LaFe11.5Al1.5By (y=0.1,0.2,0.3)和LaFe11.5Al1.5Cz (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NaZn13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(Ms)和居里温度(TC)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LaFe11.5Al1.5Hx,LaFe11.5Al1.5By和LaFe11.5Al1.5Cz11.5Al1.5H1.3,LaFe11.5Al1.5B0.1和LaFe11.5Al1.5C0.2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,LaFe11.5Al1.5H0.6的制冷能力达到259.2 J/kg,LaFe11.5Al1.5B0.1的制冷能力达到116.4 J/kg,而LaFe11.5Al1.5C0.1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-free.For LaFe13-xAlx compounds,previous studies showed that the TC can increase by substituting Co for Fe,which leads to the value of maximum magnetic entropy change (-△SM) 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 LaFe11.5Al1.5Hx(x=0,0.12,0.6 and 1.3), LaFe11.5Al1.5By(y=0.1,0.2 and 0.3) and LaFe11.5Al1.5Cz(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 LaFe11.5Al1.5,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 LaFe11.5Al1.5 hydrides, borides and carbides exhibit a considerable magnetic entropy change.The values of maximum magnetic entropy change (-△SM) reach 12.3 J/kg·K for LaFe11.5Al1.5H1.3,9.6 J/kg·K for LaFe11.5Al1.5B0.1 and 10.8 J/kg·K for LaFe11.5Al1.5C0.2 under a magnetic field change of 0-5 T,respectively.And the values of refrigerant capacity (RC) reach 259.2 J/kg for LaFe11.5Al1.5H0.6,116.4 J/kg for LaFe11.5Al1.5B0.1,and 230.4 J/kg for LaFe11.5Al1.5C0.1 under a magnetic field change of 0-5 T,respectively,indicating that LaFe11.5Al1.5H0.6 compound is a promising candidate for magnetic refrigerants.

     

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