使用电弧熔炼法制备了LaFe11.9-xCoxSi1.1B0.2( x=0.7, 0.8, 0.9)系列化合物。室温下XRD分析表明该系列化合物所成的相基本上都是NaZn13型立方结构单相，除了含有极少量的α-Fe杂相，空间群为Fm-3c。晶格常数(a/Å)随着Co含量的增加而增大，分别为11.487、11.496、11.498 Å；磁性测量发现该系列化合物的居里温度在室温附近，并且也随着Co含量的增加而增加，分别为270,290,300 K。在外场变化ΔB=1.5 T 时，该系列化合物的最大磁熵变达到金属Gd的两倍，相对制冷能力与金属Gd的相对制冷能力基本相同。
The LaFe11.9-xCoxSi1.1B0.2 (x=0.7, 0.8, 0.9) compounds were prepared by arc melting. X-ray diffraction analysis shows that the phases of LaFe11.9-xCoxSi1.1B0.2 (x=0.7, 0.8, 0.9) compounds mainly consist of the NaZn13-type cubic structure phase and a small amount of the a-Fe phase. The space group is Fm-3c. It is found that the lattice parameters and the lattice volumes have slightly increase with increasing x. the lattice parameters are found to be 11.487,11.496 and 11.498 Å and the lattice volume is found to be 1515.9,1519.4 and 1519.9 Å3 for x=0.7, 0.8 and 0.9. The magnetic measurement shows that the Curie temperature of the compounds have slightly increased with increasing Co and near the room temperature, 270, 290 and 300 K for x=0.7, 0.8 and 0.9. The maximum values of the magnetic entropy change of LaFe11.9-xCoxSi1.1B0.2 compounds are 7.47, 5.93 and 5.90 Jkg-1K-1 for x=0.7, 0.8 and 0.9 for a field change from 0 to 1.5 T. It markedly exceeds that of pure Gd at the corresponding applied field. The relative cooling power (RCP) based on the magnetic entropy change is as large as that of pure Gd at the corresponding applied field.
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