Syntheses, and crystal and electronic structures of the new Zintl phases Na₂ACdSb₂ and K₂ACdSb₂ (A=Ca, Sr, Ba, Eu, Yb): Structural relationship with Yb₂CdSb₂ and the solid solutions Sr

详细信息    查看全文

• 作者：Bayrammurad Saparov^a ; Maia Saito^a ; Svilen Bobev ; ^a ; ^{bobev@udel.edu}
• 关键词：Zintl phases ; Crystal structure ; Single-crystal X-ray diffraction ; Thermoelectric properties
• 刊名：Journal of Solid State Chemistry
• 出版年：2011
• 出版时间：February 2011
• 年：2011
• 卷：184
• 期：2
• 页码：432-440
• 全文大小：950 K

文摘

Presented are the details of the syntheses, crystal and electronic structures of a new family of Zintl phases Na₂ACdSb₂ and K₂ACdSb₂ (A=Ca, Sr, Ba, Eu, Yb), as well as the solid solutions Sr_2–xA_xCdSb₂, Ba_2–xA_xCdSb₂ and Eu_2–xYb_xCdSb₂. The structures of Na₂ACdSb₂ and K₂ACdSb₂ (A=Ca, Sr, Ba, Eu, Yb) were determined to be of a new type with the non-centrosymmetric space group Pmc2₁ (no. 26), Pearson symbol oP12, with lattice parameters a=4.684(1)−4.788(1) Å; b=9.099(3)−9.117(2) Å; c=7.837(1)−8.057(2) Å for the Na₂ACdSb₂ series, and a=4.6637(9)−5.0368(8) Å; b=9.100(2)−9.8183(15) Å; and c=7.7954(15)−8.4924(13) Å for K₂ACdSb₂, respectively. The solid solutions Sr_2–xA_xCdSb₂, Ba_2–xA_xCdSb₂ and Eu_2–xYb_xCdSb₂ (x≈1) are isostructural and isoelectronic to the recently reported Yb₂CdSb₂ (space group Cmc2₁ (no. 36), Pearson symbol cP20). All discussed structures are based upon CdSb₂^4– polyanionic layers, similar to the ones observed in Yb₂CdSb₂, with various alkali- and/or alkaline-earth cations coordinated to them. Magnetic susceptibility and Seebeck coefficient measurements on selected Eu_2–xYb_xCdSb₂ samples, taken at low temperatures up to 300 K, are also reported.