High-Temperature Formation Phases and Crystal Structure of Hot-Pressed Thermoelectric CuGaTe2 with Chalcopyrite-Type Structure

• Published in: Journal of electronic materials Vol. 47; no. 6; pp. 3105 - 3112
• Main Authors: Fujii, Yosuke, Kosuga, Atsuko
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.06.2018; Springer Nature B.V
• Subjects: Chalcopyrite; Characterization and Evaluation of Materials; Chemistry and Materials Science; Consolidation; Crystal structure; Electronics and Microelectronics; Instrumentation; International Conference on Thermoelectrics 2017; Materials research; Materials Science; Optical and Electronic Materials; Phases; Solid State Physics; Stability analysis; Structural analysis; Thermoelectric materials; Topical Collection: International Conference on Thermoelectrics 2017; crystal structure analysis; chalcopyrite-type structure; Thermoelectric; CuGaTe; synchrotron x-ray diffraction; hot-press
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-017-5929-3

Polycrystalline CuGaTe 2 with a chalcopyrite-type structure consolidated by hot-pressing is a potential candidate as a medium-temperature thermoelectric (TE) material. However, its high-temperature formation phases have rarely been reported to date. Here, we investigated the temperature-dependent formation phases and crystal structure at 300–800 K of hot-pressed CuGaTe 2 . From synchrotron x-ray diffraction data and crystal structure analysis of the heating and cooling processes, it was clarified that a certain amount of impurity phases, such as Te and CuTe, precipitated from the CuGaTe 2 matrix when the temperature was increased (to 500–650 K). This is the temperature range where CuGaTe 2 has been reported to show high TE performance. After CuGaTe 2 was heated to 800 K, such impurity phases remained, even when cooled to room temperature. They also affected the tetragonal distortion and the x -coordinate of Te in the CuGaTe 2 matrix, probably due to deficiencies of Cu and Te in the matrix. Our results reveal detailed information on the formation phases of CuGaTe 2 at high temperature and thus provide insight for evaluation of its high-temperature stability and transport properties.