Growth rate effect on microstructure and thermoelectric properties of melt grown Bi2Ba2Co2Ox textured ceramics

Bi2Ba2Co2Ox thermoelectric (TE) ceramics have been grown from the melt using the laser floating zone method at different growth rates (15, 30 and 90 mm h(-1)). Microstructural analysis has shown an improvement of the grain alignment and a reduction of secondary phases when the growth speed is decreased. These microstructural features have been reflected in the TE performances, with a reduction of the electrical resistivity and, as a consequence, at significant increase in the power factor values, reaching similar to 0.15 mW K-2 m(-1) at 650 degrees C for the samples grown at 15 mm h(-1), which is much higher than the typical values obtained in these materials.