Facile synthesis of Ag2Te nanowires and thermoelectric properties of Ag2Te polycrystals sintered by spark plasma sintering

CrystEngComm Pub Date: 2018-12-26 DOI: 10.1039/C8CE01863D

Abstract

Ag2Te nanowires with a diameter of approximately 200 nm and a length of several micrometers were prepared using a simple one-step solvothermal method without templates and surfactants. Ag(NO)3 and Na2TeO3 were used as the Ag and Te sources, respectively, and N2H4·H2O was used as the reducing agent. Based on the study of the morphology and composition of the Ag2Te nanowires obtained under different hydrothermal conditions, a possible formation mechanism of Ag2Te nanowires was proposed. An Ag-rich Ag2Te sample was prepared by adjusting the molar ratio of Ag and Te. Furthermore, Ag2Te nanowire powders were condensed to bulk materials by spark plasma sintering at 673 K for 5 min. The thermoelectric properties of the Ag2Te bulk materials were measured between 323 K and 673 K. The phase transition temperature of the transformation from α-Ag2Te to β-Ag2Te was determined to be 419 K by differential scanning calorimetry. The highest ZT values of pure Ag2Te and Ag self-doped Ag2Te bulk samples reached 0.9 and 1.1 at 623 K, respectively. These results indicate that this one-pot technique for preparing the Ag self-doped Ag2Te sample with enhanced thermoelectric performance may be widely used in other thermoelectric systems that can be fabricated by solution methods.

Graphical abstract: Facile synthesis of Ag2Te nanowires and thermoelectric properties of Ag2Te polycrystals sintered by spark plasma sintering
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