金属间化合物CePd5，PrPd5和NdPd5的晶体结构

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台金系中最富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。

Crystal Lattices of the Intermetallic Compounds CePd5, PrPd5 and NdPd5

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 CePd5,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 nm,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.