New ternary phosphides and arsenides. Syntheses, crystal structures, physical properties of Eu₂ZnP₂, Eu₂Zn₂P₃ and Eu₂Cd₂As₃

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• 作者：Jian Wang ; Sheng-Qing Xia ; Xu-Tang Tao ; Marion C. Sch?fer ; Svilen Bobev
• 关键词：Crystal structure ; Single-crystal X-ray diffraction ; Pnictides ; Zintl phases
• 刊名：Journal of Solid State Chemistry
• 出版年：2013
• 出版时间：September, 2013
• 年：2013
• 卷：205
• 期：Complete
• 页码：116-121
• 全文大小：866 K

文摘

Three new europium pnictides Eu₂ZnP₂, Eu₂Zn₂P₃ and Eu₂Cd₂As₃ have been synthesized and their structures were determined by single-crystal X-ray diffraction. Eu₂ZnP₂ is isotypic with Yb₂CdSb₂ (Cmc2₁ (No. 36); cell parameters a=4.1777(7) ?, b=15.925(3) ?, c=7.3008(12) ?), while the latter two compounds crystallize with the Ba₂Cd₂Sb₃ structure type (C2/m (No. 12); cell parameters a=15.653(5)/16.402(1) ?, b=4.127(1)/4.445(4) ?, c=11.552(4)/12.311(1) ? and ¦Â=126.647(4)/126.515(7)¡ã for Eu₂Zn₂P₃ and Eu₂Cd₂As₃, respectively). Magnetic susceptibility measurements in the interval 5-300 K confirm paramagnetic behavior and effective magnetic moments characteristic of Eu²⁺ ([Xe] 4f⁷) ground states. Temperature-dependent electrical conductivity measurements also prove that Eu₂Cd₂As₃ is a semiconducting compound with a narrow band gap of 0.059 eV below 100 K. According to TG/DSC analyses, Eu₂Cd₂As₃ starts to decompose at about 950 K.