金属间化合物CePd_5,PrPd_5和NdPd_5的晶体结构(英文)

Crystal Lattices of the Intermetallic Compounds CePd_5,PrPd_5 and NdPd_5

稀土金属对富Pd合金的氢化性能、磁学性能和催化性能有显著的影响,对Pd-RE合金系中最富Pd的化合物的研究是有意义的。本工作通过恰当的熔炼和热处理工艺制备出单相的金属间化合物CePd5,PrPd5和NdPd5,并应用X射线衍射分析确定了它们的晶体结构和晶格参数。研究发现:在Pd-Ce二元系中,最富Pd的化合物是具有CaCu5型六方结构的CePd5;而在Pd-Pr和Pd-Nd二元系中最富Pd的化合物分别是具有SmPt5型正交结构的PrPd5和NdPd5。报道了经指标化的这3种金属间化合物的X射线衍射数据,确定CePd5的晶格参数a=0.5372nm,c=0.4178nm;PrPd5和NdPd5的晶格参数分别是a=0.5278nm,b=0.9239nm,c=2.575nm和a=0.5265nm,b=0.9219nm,c=2.570nm。并对Pd-RE合金系和Pt-RE合金系中最富Pd化合物的化学计量和晶体结构进行了对比。

Rare earth metals have distinct influence on hydrogenation, magnetic and catalytic properties of the Pd-rich alloys. Investigation on the most Pd-rich compounds in the Pd-RE systems is significant. In this work, single phase compounds CePds, PrPd5 and NdPd5 were prepared by a proper smelting and heat treatment. X-ray diffraction was used to determine their structure and lattice parameters. It is found that the most Pd-rich compound in the Pd-Ce system is CePd5 with the hexagonal CaCu5-type structure, and that in the Pd-Pr and Pd-Nd system is PrPd5 and NdPd5 with the orthorhombic SmPt5-type structure, respectively. X-ray diffraction data for the three intermetallic compounds have been reported. Following lattice parameters have been obtained： a=0.5372 nm, c=0.4178 nm for CePd5; a=0.5278 nm, b=0.9239 nm, c=2.575 nm for PrPd5; a=0.5265 nm, b=0.9219 rim, c=2.570 nm for NdPd5. The stoichiometries and the crystal structures of the most Pd-rich compounds in the Pd-RE systems have been compared with those in the Pt-RE systems.