Jia Feng, Zhang Shu, Zhang Xiaokun, Peng Xiaoli, Zhang Haitao, Xiang Yong
State Key Laboratory of Electronic Thin Films & Integrated Devices, School of Energy Science and Engineering, University of Electronic Science and Technology of China, Chengdu, Sichuan 611731 (P.R. China).
Chemistry. 2014 Nov 24;20(48):15941-6. doi: 10.1002/chem.201403797. Epub 2014 Oct 8.
Control over phase stabilities during synthesis processes is of great importance for both fundamental studies and practical applications. We describe herein a facile strategy for the synthesis of Cu2Se with phase selectivity through a simple solvothermal method. In the presence and absence of SbCl3, monoclinic α-Cu2Se and cubic β-Cu2Se can be synthesized, respectively. The formation of α-Cu2Se requires optimization of the Cu/Se molar ratio in the starting reagents, the reaction temperature, as well as the timing for the addition of SbCl3. Differential scanning calorimetry of the synthesized α-Cu2Se has shown that a part of it undergoes a phase transition to β-Cu2Se at 135 °C, and that this phase transition is irreversible on cooling to ambient temperature. Kinetic studies have revealed that in the presence of Sb species the kinetically favored β-Cu2Se transforms to the thermodynamically favored α-Cu2Se. In this β-to-α phase transition process, the distribution of Cu ions in β-Cu2Se, as determined by the Cu/Se ratio and temperature, is likely to play a crucial role.
在合成过程中控制相稳定性对于基础研究和实际应用都非常重要。我们在此描述一种通过简单溶剂热法以相选择性合成Cu2Se的简便策略。在存在和不存在SbCl3的情况下，分别可以合成单斜α-Cu2Se和立方β-Cu2Se。α-Cu2Se的形成需要优化起始试剂中的Cu/Se摩尔比、反应温度以及添加SbCl3的时机。对合成的α-Cu2Se进行差示扫描量热法表明，其中一部分在135°C时会发生向β-Cu2Se的相变，并且在冷却至室温时这种相变是不可逆的。动力学研究表明，在存在Sb物种的情况下，动力学上有利的β-Cu2Se会转变为热力学上有利的α-Cu2Se。在这个β到α的相变过程中，由Cu/Se比和温度决定的β-CuSe中Cu离子的分布可能起着关键作用。
