New Layered Germanide Halides RE2GeX2 (RE = Y, Gd; X = Br, I)
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- 作者：Mar'yana Lukachuk ; Reinhard K. Kremer ; Hansjü ; rgen Mattausch ; Arndt Simon
- 刊名：Inorganic Chemistry
- 出版年：2007
- 出版时间：April 16, 2007
- 年：2007
- 卷：46
- 期：8
- 页码：3231 - 3235
- 全文大小：215K
- 年卷期：v.46,no.8(April 16, 2007)
- ISSN：1520-510X
文摘
The title compounds were synthesized from RE, REX3, and Ge under an Ar atmosphere at 1200-1370 K. Y2GeI2and Gd2GeI2 crystallize in space group R
m with lattice constants a = 4.2135(3) and 4.2527(1) Å and c = 31.480(2)and 31.657(1) Å, respectively. Gd2GeBr2 crystallizes in two modifications, the 1T-type (space group Pm1; a =4.1668(2) Å, c = 9.8173(6) Å) and the 3R-type (space group Rm; a = 4.1442(9) Å, c = 29.487(7) Å). Thestructural motifs of RE2GeX2 compounds are Ge-centered slightly distorted RE6 octahedra connected via theircommon edges and extending in the a and b directions. The resulting close-packed double layers are separatedby halogen atoms. The electrical resistivity measurements revealed semiconductor behavior for Y2GeI2 and Gd2GeI2and a metal-semiconductor transition for 1T-Gd2GeBr2. Magnetic susceptibility and heat capacity measurementsshow long-range magnetic ordering for Gd2GeI2 and 1T-Gd2GeBr2 at ~15 and ~13 K, respectively.
m with lattice constants a = 4.2135(3) and 4.2527(1) Å and c = 31.480(2)and 31.657(1) Å, respectively. Gd2GeBr2 crystallizes in two modifications, the 1T-type (space group Pm1; a =4.1668(2) Å, c = 9.8173(6) Å) and the 3R-type (space group Rm; a = 4.1442(9) Å, c = 29.487(7) Å). Thestructural motifs of RE2GeX2 compounds are Ge-centered slightly distorted RE6 octahedra connected via theircommon edges and extending in the a and b directions. The resulting close-packed double layers are separatedby halogen atoms. The electrical resistivity measurements revealed semiconductor behavior for Y2GeI2 and Gd2GeI2and a metal-semiconductor transition for 1T-Gd2GeBr2. Magnetic susceptibility and heat capacity measurementsshow long-range magnetic ordering for Gd2GeI2 and 1T-Gd2GeBr2 at ~15 and ~13 K, respectively.