Intentional Carrier Doping to Realize n-Type Conduction in Zintl Phases Eu_5-LaIn_2.2Sb₆

Due to the tunable electrical transport properties and lower thermal conductivity, Zintl phase compounds have been considered as a promising candidate for thermoelectric applications. Most Sb-based Zintl compounds exhibit essentially p-type conduction as result of the cation vacancy. Herein, n-type Zintl phases Eu_5-LaIn_2.2Sb₆ has been successfully synthesized via controlling the vacancy defect combined with intentional electron doping. Excess of In would occupy the vacancy while La doping enables the electron to be the major carrier at the measured temperate range, realizing the n-type conduction for Eu_5-LaIn_2.2Sb₆ (y ≥ 0.04). Meanwhile, the thermal conductivity of Eu_5-LaIn_2.2Sb₆ reduces from 0.90 W/mK to 0.72 W/mK at 583 K derived from the La doping-induced disorder. The maximum thermoelectric figure of merit zT = 0.13 was obtained. This work firstly realizes the n-type conduction in Eu₅In₂Sb₆, which sheds light on the strategy to synthesize n-type Zintl thermoelectric materials and promotes the practical applications of Zintl thermoelectric devices.