Thermoelectric performance of Ge1-xSnxTe (0 ≤ x ≤ 0.2) prepared by facile method

Abstract

Ge1-xSnxTe (0 ​≤ ​x ​≤ ​0.20) alloys have been fabricated through a novel hydrogen decrepitation method followed by a spark plasma sintering process. The impact of Sn substitution on the Structural, morphological and thermoelectric performance of GeTe have been systematically studied. The Seebeck coefficient of all Ge1-xSnxTe (0 ​≤ ​x ​≤ ​0.20) alloys showed the positive sign value at an entire temperature range, while Ge0.95Sn0.05Te showed high in Seebeck coefficient value compared to other samples. The electrical resistivity of Ge1-xSnxTe (0 ​≤ ​x ​≤ ​0.20) alloys were increases with increasing Sn2+(x) content, due to its lowering the carrier density and higher charge carrier mobility. Concomitantly, the isoelectronic substitution of Sn2+ ions at the Ge site effectively to suppress the thermal conductivity of GeTe. Sn substitution drastically reduced the thermal conductivity of Ge1-xSnxTe alloys from 4.0 Wm−1K−1 to 2.6 Wm−1K−1 ​at 723 ​K, which was mainly due to anharmonicity in phonon vibration caused by lattice distortion. As a result, Ge0.95Sn0.05Te alloy exhibited a high dimensionless figure of merit (ZT) of ∼0.63 ​at 723 ​K, which is ∼17.4% higher than pristine GeTe.