Improved ZT in ball‐milled and spark plasma sintered Cu₁₅As₃₀Te₅₅ glass‐ceramics

Abstract

The influence of ball milling followed by Spark Plasma Sintering (SPS) on the thermoelectric properties of the Cu 15 As 30 Te 55 glass composition has been investigated by means of X-ray diffraction, scanning electron microscopy, and differential scanning calorimetry. The microstructure, composition, and thermal stability of the ball-milled samples before and after SPS have been correlated with the electrical and thermal transport properties. Upon ball milling, a glass-to-glass transformation is evidenced for short ball-milling times, followed by crystallization of the metastable β-As 2 Te 3 phase within the glassy matrix. This glass-to-glass transformation favors the occurrence of the β-As 2 Te 3 phase during the SPS process. A maximum figure of merit ZT of 0.29 at 400 K is obtained in the sample exhibiting the largest β-As 2 Te 3 crystalline fraction. This ZT value is twice as high as the value obtained for the glass-ceramic sintered from non-ball-milled powder. K E Y W O R D Sball milling, chalcogenide glass-ceramics, thermoelectric materials