论文标题
Fe2Val Heusler化合物的意外带隙增加
Unexpected band gap increase in the Fe2VAl Heusler compound
论文作者
论文摘要
了解材料的电子结构对于能源应用至关重要，以使其性能合理化并提出替代方案。热电应用的材料通常是小间隙半导体，应具有较高的优点ZT。即使Fe2Val Heusler化合物具有不错的ZT，其导电性质（半金属或半导体）尚未在低温下特别阐明。在本文中，我们将DFT计算集中在温度对Fe2Val带隙的影响上。与通常观察到的相反，我们表明温度升高和热激活的Al/V反转缺陷的形成（实验性观察），打开带隙。这种异常行为是核对使用标准GGA功能在FE2VAL化合物上进行的所有带隙测量的关键，并且可能是改善该材料家族的热电特性的有效方法。
Knowing the electronic structure of a material is essential in energy applications to rationalize its performance and propose alternatives. Materials for thermoelectric applications are generally small-gap semiconductors and should have a high figure of merit ZT. Even if the Fe2VAl Heusler compound has a decent ZT, its conductive nature (semi-metal or semiconductor) is not yet clarified especially at low temperature. In this paper, we focus our DFT calculations on the effect of temperature on the bandgap of Fe2VAl. In contrast to what is usually observed, we show that both the temperature increase and the formation of thermally-activated Al/V inversion defects (observed experimentally), open the bandgap. Such an unusual behavior is the key for reconciling all bandgap measurements performed on the Fe2VAl compound using a standard GGA functional and could be an efficient way for improving the thermoelectric properties of this family of materials.
