Low-cost and high-performance N-type Mg3Sb1.5Bi0.5-based Thermoelectric materials for medium and low temperature applications via Zn and Se co-doping

Abstract

Improving the power factor is a crucial parameter in enhancing thermoelectric performance, making it essential to find an effective strategy for its enhancement. This study examines n-type Mg₃Sb_1.5Bi₀.5-based thermoelectric materials doped with Zn and Se. Se is added to adjust the carrier concentration, while Zn is introduced into Mg_3.2Sb_1.5Bi_0.49Se_0.01 to manipulate the carrier scattering mechanism. Experimental results indicate a significant increase in carrier mobility from 42.21 cm² V^− 1 s^− 1 to 73.92 cm² V^− 1 s^− 1, leading to a substantial enhancement in electrical conductivity and power factor across the entire temperature range under investigation. Additionally, due to reduced lattice thermal conductivity resulting from the introduction of efficient phonon scattering centers in the Zn and Se co-doped sample, Mg_3.18Zn_0.02Sb_1.5Bi_0.49Se_0.01 attains a maximum ZT value of 1.77 at 623 K, resulting in a notable average ZT ≈ 1.24 over the temperature range of 300 to 673 K. Given its cost-effectiveness and low toxicity, this material is anticipated to replace the commercially available n-type Bi₂Te₃-based thermoelectric materials commonly used at moderate and low temperatures.