Structural Studies of Two Novel La-Sn Compounds: La30Sn30 and La32Ni2Sn35.

Yang, A. S.

Technical Information Center Oak Ridge Tennessee

关键词: Intermetallic compounds;    Lanthanum;    Crystal structure;    X ray diffraction;    Analytical chemistry;   

RP-ID  :  DE2006850066

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

Two novel intermetallic compounds containing lanthanum and tin have been obtained for the first time. Single crystal structures of these two phases, La30Sn30 and La32Ni2Sn35 have been studied by X-ray crystallography. La30Sn30 is a new 1:1 binary containing La and Sn and has been refined in the Cmmm space group. This phase was made at high temperatures (>12OO deg C) from a loaded composition of La68Sn70. Unlike the reported 1:l binary, LaSn which crystallizes in the Cmcm space group (only powder X-ray diffraction studies reported), La30Sn30 forms good crystals for structural determination. The crystal structure of La3oSn30 show Sn-Sn dimers and Sn-centered, face-sharing biaugmented triangular prisms composed of La atoms. La30Sn30 does not belong to any known structure -type. La32Ni2Sn35 was obtained in high yields at high temperatures (>12OO deg C) and refined in the 14/mmm space group. It belongs to the USi structure type in which the Ni/Sn atoms occupy the Si sites, and La/Sn atoms occupy the U sites. The crystal structure of La32Ni2Sn35 consists of buckled sheets made from La-centered, comer-shared octahedra of Sn. These sheets are intraconnected through Ni-Sn-Ni bonds along the c-axis. The crystals are not air sensitive, unlike La30Sn30, which can be attributed to the presence of Ni in the crystal structure.