ABSTRACT

The Heusler alloys are promising material for various applications, including thermoelectric power generators. There are several ways to improve their properties, among which the substitution of constituent elements, nanostructuring, temperature treatment, thin films engineering etc. This work is devoted to the experimental study of thermoelectric properties of Fe–V–Al-based Heusler alloys with different compositions under high pressure. The Seebeck coefficient and electrical resistance of several compounds were measured as a function of applied pressure up to 10 GPa at room temperature. The experimental results demonstrated a diversity of pressure responses of the thermoelectric properties that can be observed in chemically similar Heusler alloys under variation in their compositions. Moderate enhancing of the thermoelectric power factor, S²/r (where S is the Seebeck coefficient and r is the electrical resistivity) was observed in Fe-rich Fe_2.1V_0.91Al_0.99 compound at a pressure about ∼1 GPa. It was found that all alloys with weak deviation from stoichiometric composition had a feature in their S (P) pressure behavior at P∼2 GPa which could be related to semimetal-metal phase transition.

摘要

Heusler 合金是用于各种应用的有前途的材料，包括热电发电机。改善其性能的方法有多种，其中包括组成元素的置换、纳米结构、温度处理、薄膜工程等。 本工作致力于不同温度下 Fe-V-Al 基 Heusler 合金的热电性能的实验研究。高压下的组合物。测量了几种化合物的塞贝克系数和电阻，作为室温下高达 10 GPa 的外加压力的函数。实验结果表明，在化学成分相似的 Heusler 合金中可以观察到热电特性的压力响应的多样性。适度提高热电功率因数，S ² / r（其中S是塞贝克系数，r是电阻率）在约 1 GPa 的压力下在富含 Fe 的 Fe _2.1 V _0.91 Al _0.99化合物中观察到。发现所有与化学计量成分偏差较弱的合金在P ∼ 2 GPa 时的S ( P ) 压力行为都有一个特征，这可能与半金属-金属相变有关。