Synthesis, crystal and electronic structures, and properties of the new pnictide semiconductors A2CdPn2 (A = Ca, Sr, Ba, Eu; Pn = P, As).
Synthesis, crystal and electronic structures, and properties of the new pnictide semiconductors A2CdPn2 (A = Ca, Sr, Ba, Eu; Pn = P, As).
复制标题
DOI：
10.1021/ic200286t
复制
发表时间：
2011-07
影响因子：
4.6
通讯作者：
Jian Wang;Min Yang;Mingyan Pan;S. Xia;X. Tao;Hua He;Gregory M. Darone;S. Bobev
中科院分区：
文献类型：
--
作者：
Jian Wang;Min Yang;Mingyan Pan;S. Xia;X. Tao;Hua He;Gregory M. Darone;S. Bobev
通过高温金属熔剂反应合成了一系列三元Zintl相Ca(2)CdP(2)、Ca(2)CdAs(2)、Sr(2)CdAs(2)、Ba(2)CdAs(2)和Eu(2)CdAs(2)，并通过单晶X射线衍射表征了它们的结构。它们属于 Yb(2)CdSb(2) 结构类型，结晶在斜方空间群 Cmc2(1)（No. 36，Z = 4）中，晶胞尺寸为 a = 4.2066(5)、4.3163(5)、4.4459(7)、4.5922(5)、4.4418(9) Å； b = 16.120(2)、16.5063(19)、16.904(3)、17.4047(18)、16.847(4) 埃； c = 7.0639(9)、7.1418(8)、7.5885(11)、8.0526(8)、7.4985(16) Å，对于 Ca(2)CdP(2) (R1 = 0.0152、wR2 = 0.0278)、Ca(2)CdAs(2) (R1 = 0.0165，wR2 = 0.0290)、Sr(2)CdAs(2)（R1 = 0.0238，wR2 = 0.0404）、Ba(2)CdAs(2)（R1 = 0.0184，wR2 = 0.0361）和 Eu(2)CdAs(2)（R1 = 0.0203，wR2） = 0.0404），分别。其中，Ca(2)CdAs(2)被发现与另一种密切相关的结构形成，这取决于实验条件——单斜空间群Cm（No.8，Z = 10），其晶格常数a = 21.5152(3) Å，b = 4.30050(10) Å，c = 14.3761(2) Å和β = 110.0170(10)°（R1 = 0.0461，wR2 = 0.0747）。两种形式的 Ca(2)CdAs(2) 的紫外/可见光吸收光谱显示带隙约为 1.0 eV，表明具有半导体特性，这一点也通过基于密度泛函理论的电子能带结构计算得到了证实。讨论了差示扫描量热法测量两种 Ca(2)CdAs(2) 多晶型物的热稳定性和相变的结果。还提供了 Eu(2)CdAs(2) 的磁化率测量结果，表明二价 Eu(2+) 阳离子。
A series of ternary Zintl phases, Ca(2)CdP(2), Ca(2)CdAs(2), Sr(2)CdAs(2), Ba(2)CdAs(2), and Eu(2)CdAs(2), have been synthesized through high temperature metal flux reactions, and their structures have been characterized by single-crystal X-ray diffraction. They belong to the Yb(2)CdSb(2) structure type and crystallize in the orthorhombic space group Cmc2(1) (No. 36, Z = 4) with cell dimensions of a = 4.2066(5), 4.3163(5), 4.4459(7), 4.5922(5), 4.4418(9) Å; b = 16.120(2), 16.5063(19), 16.904(3), 17.4047(18), 16.847(4) Å; c = 7.0639(9), 7.1418(8), 7.5885(11), 8.0526(8), 7.4985(16) Å for Ca(2)CdP(2) (R1 = 0.0152, wR2 = 0.0278), Ca(2)CdAs(2) (R1 = 0.0165, wR2 = 0.0290), Sr(2)CdAs(2) (R1 = 0.0238, wR2 = 0.0404), Ba(2)CdAs(2) (R1 = 0.0184, wR2 = 0.0361), and Eu(2)CdAs(2) (R1 = 0.0203, wR2 = 0.0404), respectively. Among these, Ca(2)CdAs(2) was found to form with another closely related structure, depending on the experimental conditions--monoclinic space group Cm (No. 8, Z = 10) with lattice constants a = 21.5152(3) Å, b = 4.30050(10) Å, c = 14.3761(2) Å and β = 110.0170(10)° (R1 = 0.0461, wR2 = 0.0747). UV/vis optical absorption spectra for both forms of Ca(2)CdAs(2) show band gaps on the order of 1.0 eV, suggesting semiconducting properties, which have also been confirmed through electronic band structure calculations based on the density-functional theory. Results from differential scanning calorimetry measurements probing the thermal stability and phase transitions in the two Ca(2)CdAs(2) polymorphs are discussed. Magnetic susceptibility measurements for Eu(2)CdAs(2), indicating divalent Eu(2+) cations, are presented as well.