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Effect of excess Ge and Te on thermoelectric performance of GeTe
Author(s) -
Dong Yuan,
Gao Junling,
Zou Ping,
Xu Guiying
Publication year - 2021
Publication title -
international journal of applied ceramic technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.4
H-Index - 57
eISSN - 1744-7402
pISSN - 1546-542X
DOI - 10.1111/ijac.13750
Subject(s) - materials science , spark plasma sintering , thermoelectric effect , seebeck coefficient , crystallite , thermoelectric materials , microstructure , vacancy defect , analytical chemistry (journal) , sintering , thermal conductivity , metallurgy , condensed matter physics , composite material , thermodynamics , physics , chemistry , chromatography
GeTe is a medium‐temperature thermoelectric material with excellent performance. The thermoelectric performance of GeTe is affected by the carrier concentration generated by Ge vacancy. Therefore, it is of important to study the effect of excess Ge or Te on the thermoelectric performance of GeTe. In this paper, Ge x Te y materials ( x : y = 1:1.08, 1:1.06, 1:1.04, 1:1, 1.05:1, 1.075:1, and 1.1:1) were fabricated by high‐pressure sintering (HPS) and spark plasma sintering (SPS), respectively, to study the effects of different Ge/Te atomic ratios and preparation process on the thermoelectric properties of polycrystalline GeTe. The composition and microstructure were investigated by an X‐ray diffraction method (XRD) and field‐emission scanning electron microscope (FESEM). The thermoelectric performance was tested from 303 to 703 K. The measurement results show that the Seebeck coefficient of Ge x Te y increases and the conductivity decreases with the decreasing in Te content or the increasing in Ge content. Ge 1 Te 1 exhibits the highest power factor because its Seebeck coefficient and conductivity are at an average level. Owing to the presence of pure Ge and the decrease of Ge vacancy, the lattice thermal conductivities of samples with excess Ge are higher than that of Ge 1 Te 1 . Ge 1 Te 1 sintered by HPS has the highest ZT max value, reaching 1.37 at 723 K.