Enhancing thermoelectric performance of BaMg2-based compounds by forming solid solutions and biaxial strain. (3rd September 2021)

• Record Type: Journal Article
• Authors: Wang, Jiaxi; Li, Jia; Wang, Yafan; He, Fuli; Zhang, Qian; Wang, Guang; Jin, Yuming; Yin, Fuxing
• Is Part Of: Journal of physics. Volume 54:Number 48(2021)
• Publication Date: 2021-09-03
• Subjects: thermoelectric -- biaxial strain -- first principles -- Zintl phase -- Boltzmann transport; Physics -- Periodicals; 530
• DOI: 10.1088/1361-6463/ac203b
• Languages: English
• ISSNs: 0022-3727

Abstract

Abstract: Two strategies were proposed to optimize the thermoelectric performance of BaMg2 (Bi, Sb) through a solid solution method and to tune the crystal field splitting energy of orbital by using first principles calculation and Boltzmann transport theory. The increase in Sb content leads to decreased weight carrier mobility due to the changes in the electronic structure. The lattice thermal conductivity for BaMg2 SbBi can be as low as 0.45 W m −1 K −1, which is lower than those of other compounds. The highest ZT of ∼0.88 for BaMg2 SbBi has been obtained at 750 K with n-type doping carrier concentration of −8.28 × 10 18 cm −3, indicating that reaching the optimal Sb content (i.e. BaMg2 SbBi) can make a significant contribution to the maximization of the ZT of n-type BaMg2 (Bi, Sb) solid solutions. Adjusting the crystal field splitting energy increases the effective mass of density of states, which causes the change in power factor (PF) value and achieves a maximum PF value. When the tensile strain for BaMg2 Bi2, BaMg2 SbBi, and BaMg2 Sb2 is 2%, 2%, and 6%, the ZT value is significantly improved, respectively. Therefore, minimizing crystal field splitting energy is also effective in the optimization of the ZT value.