Effect of sintering in ball-milled K2Bi8Se13 thermoelectric nano-composites

► K2Bi8Se13-based composites consisting of nanocrystalline and amorphous phases. ► Sintering results multiple-step crystallization with variable activation energies. ► Thermoelectric properties follow a step-like behavior during sintering. ► Properties are attributed to the strain relaxation, nucleation and grain growth.