Synthesis, Structure, and Properties of the Electron-Poor II鈥揤 Semiconductor ZnAs

详细信息    查看全文

• 作者：Andreas Fischer ; Daniel Ekl枚f ; Daryn E. Benson ; Yang Wu ; Ernst-Wilhelm Scheidt ; Wolfgang Scherer ; Ulrich H盲ussermann
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：August 18, 2014
• 年：2014
• 卷：53
• 期：16
• 页码：8691-8699
• 全文大小：470K
• ISSN：1520-510X

文摘

ZnAs was synthesized at 6 GPa and 1273 K utilizing multianvil high-pressure techniques and structurally characterized by single-crystal and powder X-ray diffraction (space group Pbca (No. 61), a = 5.6768(2) 脜, b = 7.2796(2) 脜, c = 7.5593(2) 脜, Z = 8). The compound is isostructural to ZnSb (CdSb type) and displays multicenter bonded rhomboid rings Zn₂As₂, which are connected to each other by classical two-center, two-electron bonds. At ambient pressure ZnAs is metastable with respect to Zn₃As₂ and ZnAs₂. When heating at a rate of 10 K/min decomposition takes place at 700 K. Diffuse reflectance measurements reveal a band gap of 0.9 eV. Electrical resistivity, thermopower, and thermal conductivity were measured in the temperature range of 2鈥?00 K and compared to thermoelectric ZnSb. The room temperature values of the resistivity and thermopower are 1 惟 cm and +27 渭V/K, respectively. These values are considerably higher and lower, respectively, compared to ZnSb. Above 150 K the thermal conductivity attains low values, around 2 W/m路K, which is similar to that of ZnSb. The heat capacity of ZnAs was measured between 2 and 300 K and partitioned into a Debye and two Einstein contributions with temperatures of 胃_D = 234 K, 胃_E1 = 95 K, and 胃_E2 = 353 K. Heat capacity and thermal conductivity of ZnSb and ZnAs show very similar features, which possibly relates to their common electron-poor bonding properties.