Abstract
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 Eu5−yLayIn2.2Sb6 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 Eu5−yLayIn2.2Sb6 (y ≥ 0.04). Meanwhile, the thermal conductivity of Eu5−yLayIn2.2Sb6 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.
Highlights
With the rapid developments of the global economy and industrial production, energy crises and environmental pollution have been critical issues in these years
The efficiency of a thermoelectric material is generally characterized by the thermoelectric figure of merit, zT = α2 T/ρκ, where α is Seebeck coefficient, T is the absolute temperature (K), ρ is the electrical resistivity, and κ is the thermal conductivity (W/mK) [1,2,3,4,5]
In 1995, Slack proposed the concept of phonon glass-electron crystal (PGEC), which implies high-performance thermoelectric materials contain electron-transport and phonon-scattering building blocks [6]
Summary
With the rapid developments of the global economy and industrial production, energy crises and environmental pollution have been critical issues in these years. In 1995, Slack proposed the concept of phonon glass-electron crystal (PGEC), which implies high-performance thermoelectric materials contain electron-transport and phonon-scattering building blocks [6] In this case, the electrical and thermal transport properties can be decoupled at a certain degree with independent functional blocks. Sb-based Zintl phase compounds normally exhibit p-type conduction, deriving from the instinct cationic vacancy [9]. It is well-know that a high-efficiency thermoelectric device requires p-legs and n-legs with a high figure of merit, zT, to realize energy conversion.
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