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
Volume116
Issue15
Date Published2014/10/21/
Abstract

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.