Synthesis, Superstructure, and Vacancy-Ordering in 2H-CuxTa1+ySe2 (x, y = 0.52, 0 and 0.16, 0.08)
Synthesis, Superstructure, and Vacancy-Ordering in 2H-CuxTa1+ySe2 (x, y = 0.52, 0 and 0.16, 0.08)
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DOI：
10.1002/zaac.201400335
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发表时间：
2015-02
期刊：
影响因子：
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通讯作者：
Sk Imran Ali;S. Mondal;S. Smaalen
中科院分区：
文献类型：
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作者：
Sk Imran Ali;S. Mondal;S. Smaalen
用化学气相传输法生长了CuxTa 1 + ySe 2单晶。在稍微不同的反应条件下，由相同标称组成的反应物的混合物获得不同组成的单晶。有人建议，不同直径的安瓿意味着不同的对流和扩散的质量传输的贡献，从而负责不同的比例的Cu，Ta，和Se的运输量。2 H-Cu_（0.52）TaSe_2（x = 0.52，y = 0）在较窄的晶体（直径15 mm）中形成。晶体结构基于TaSe 2层的MoS 2型堆叠。Cu在四面体位置上的部分有序化导致了具有六方Pm 2对称性的2a 0 × 2b 0 × c 0超结构[a0 = 3.468（1）A，c 0 = 13.568（3）A]。2 H-Cu_（0.16）Ta_（1.08）Se_2（x = 0.16，y = 0.08）在较宽的晶界（直径18 mm）中形成。它具有NbS 2型堆叠。没有形成超结构，但在交替的货车德瓦耳斯能隙中存在Cu和插入的Ta负责对称性从P63/mmc降低到Pm 1 [a0 = 3.439（2）A，c 0 = 12.870（2）A]。在两种反应中，在安瓿的较热侧形成单晶，温度高达1168 K。
Single crystals of CuxTa1+ySe2 were grown by chemical vapor transport. Single crystals of different compositions were obtained at slightly different reaction conditions from mixtures of the reactants of the same nominal composition. It is suggested that different diameters of the ampoules imply different contributions of convection and diffusion to the mass transport, and thus are responsible for different ratios of the amount of Cu, Ta, and Se transported. 2H-Cu0.52TaSe2 (x = 0.52, y = 0) is formed in the narrower ampoule (diameter 15 mm). The crystal structure is based on the MoS2 type of stacking of TaSe2 layers. Partial ordering of Cu over the tetrahedral sites is responsible for a 2a0 × 2b0 × c0 superstructure with hexagonal Pm2 symmetry [a0 = 3.468 (1) A, c0 = 13.568 (3) A]. 2H-Cu0.16Ta1.08Se2 (x = 0.16, y = 0.08) is formed in the wider ampoule (diameter 18 mm). It possesses a NbS2-type of stacking. A superstructure is not formed, but the presence of Cu and intercalated Ta in alternating van der Waals gaps is responsible for the reduction of symmetry from P63/mmc to Pm1 [a0 = 3.439 (2) A, c0 = 12.870 (2) A]. Single crystals are formed towards the hotter side of the ampoules up to a temperature of 1168 K in both reactions.