摘要
采用真空电弧熔炼和放电等离子烧结技术制备了Full-Heusler合金Fe_2VAl,利用XRD、XPS对合金的物相结构与成分进行表征,在300～800K温度区间内测试了合金的Seebeck系数、电阻率、热导率等热电参数,并将实验结果与基于L2_1有序结构Fe_2VAl合金的模拟计算值进行了比较。结果表明,实验所制的合金样品中Fe、Al、V原子比接近于2∶1∶1,基本满足Fe_2VAl合金的成分配比;结合XRD衍射谱及10K下合金的饱和磁矩可知,所制合金样品中除了完全有序的L2_1结构相外,还存在部分的B2相。另一方面,基于热电性能测试结果可知,所制Fe_2VAl合金表现出典型的n型半导体特性,其Seebeck系数和电阻率随着温度的升高而降低,这与利用VASP和BoltzTraP软件包结合计算得到的L2_1结构Fe_2VAl合金的热电参数随温度(300～800K)的变化趋势相符合;合金的热导率随着温度的升高呈先降低后升高的趋势,在500K附近具有极小值,而无量纲参数热电优值ZT在500K附近达到最大值,约为0.052。
The Full-Heusler alloy Fe2VAl was prepared by vacuum arc melting and spark plasma sintering approaches. By means of XRD and XPS,the phase structure and composition of the as-prepared alloy were characterized. The thermoelectric parameters including the Seebeck coefficient,resistivity and thermal conductivity were measured in the temperature range of 300~800 K,which were compared with those calculated based on the Fe2VAl alloy in L21 ordered structure. The results show that the atomic ratio of Fe,Al and V in the as-prepared alloy sample is close to 2∶1∶1,which basically satisfies the distribution ratio in Fe 2VAl alloy. Aided by the XRD diffraction spectra and the saturation magnetic moment of the Fe2VAl alloy measured at 10 K,it can be known that in addition to the fully ordered L21 structure,a small portion of B2 structure is present in the alloy sample. Besides,the results of thermoelectric performance tests indicate that the as-prepared Fe 2VAl alloy exhibits the typical characteristics of n-type semiconductor,and its Seebeck coefficient (absolute value) and resistivity decrease with the increase of temperature (300~800 K),which is in a good coincidence with the changing trend calculated by VASP and BoltzTraP software package;the thermal conductivity of the alloy first decreases and then increases with the increase of temperature,and has a minimum value around 500 K,while the dimensionless thermoelectric figure of merit ZT reaches a maximum of 0.052 at approx. 500 K.
作者
王文静
卢志红
李春蓉
尹航
Wang Wenjing;Lu Zhihong;Li Chunrong;Yin Hang(State Key Laboratory of Refractories and Metallurgy,Wuhan University of Science and Technology,Wuhan 430081,China)
出处
《武汉科技大学学报》
CAS
北大核心
2019年第2期81-87,共7页
Journal of Wuhan University of Science and Technology
基金
国家自然科学基金资助项目(11574242)
