Texturing behaviors and kinetics of NaCo2O4-δ thermoelectric materials

Abstract

Polycrystalline NaCo2O4-δ materials were prepared using the solid-state reaction technique. The processing dependence of texturing evolution of NaCo2O4-δ was investigated quantitatively. The results indicate that the extent of texture increased with increasing process duration and then reached the maximum when the materials were sintered at 900°C for 12 h. The texturing kinetics obeys an exponential relationship, suggesting that the texturing processing is dominated by self-diffusion mechanism. However, the texture extent decreased when the annealing time exceeded 12 h. The experimental results may provide new insights into the optimization of processing parameters for the fabrication of polycrystalline NaCo2O4-δ materials with the desired microstructure. © 2007 The American Ceramic Society.