Tunable charge carriers and thermoelectricity of single-crystal Ba8Ga16Sn30

TL;DR

This study investigates how growth conditions affect charge carriers and thermoelectric properties in Ba8Ga16Sn30 single crystals, revealing high sensitivity to synthesis methods and potential for optimizing thermoelectric performance.

Contribution

It demonstrates the tunability of charge carriers in Ba8Ga16Sn30 through different flux growth methods, highlighting the importance of synthesis conditions for thermoelectric applications.

Findings

Crystals grown in Sn flux are n-type; those in Ga flux are p-type.

Charge carrier density and type are highly sensitive to growth conditions.

Transport properties vary significantly with synthesis method.

Abstract

We have grown single crystals of the type-VIII intermetallic clathrate Ba8Ga16Sn30 from both Sn and Ga flux, evaluated their compositions through electron microprobe analysis and studied their transport properties through measurements on temperature dependent resistivity, thermopower and Hall coefficient. Crystals grown in Sn flux show n-type carriers and those from Ga flux show p-type carriers, whereas all measured compositions remain very close to the stoichiometric 8:16:30 proportion of Ba:Ga:Sn, expected from charge-balance principles. Our results indicate a very high sensitivity of the charge carrier nature and density with respect to the growth conditions, leading to relevant differences in transport properties which point to the importance of tuning this material for optimal thermoelectric performance.