Grain growth and structural relaxation of nanocrystalline Bi2Te3

TitleGrain growth and structural relaxation of nanocrystalline Bi2Te3
Publication TypeJournal Article
Year of Publication2014
AuthorsHumphry-Baker, SA, Schuh, CA
JournalJournal of Applied Physics
Date Published2014/10/21/

Recovery and grain growth behavior is investigated systematically for the nanocrystalline thermoelectric compound bismuth telluride, synthesized by mechanical alloying. During annealing treatments at elevated temperatures, structural evolution is tracked using x-ray diffraction, electron microscopy and calorimetry. Below a homologous temperature of about 0.6T(m), grain growth occurs slowly with an activation energy of 89 kJ/mol. However above this temperature grain growth becomes more rampant with an activation energy of 242 kJ/mol. The transition is attributed to a shift from a relaxation or recovery process that includes some reordering of the grain boundary structure, to a more conventional diffusionally-limited grain growth process. By extrapolating the measured grain growth and microstrain evolution kinetics, a thermal budget map is constructed, permitting recommendations for improving the thermoelectric properties of nanocrystalline materials processed via a powder route. (C) 2014 AIP Publishing LLC.