Thermoelectric properties-texture relationship in highly oriented Ca3Co4O9 composites

The correlation between thermoelectric properties and texture strength is discussed within the framework of Ca3Co4O9 textured ceramics. Based on an innovative method of x-ray diffraction analysis, the distribution density (i.e., the degree of orientation) of composite material composed of Ca3Co4O9 powder and single crystals was determined. Electrical resistivity of the prepared composites was shown to be reduced with increasing single crystals weight ratios and, in parallel, was directly correlated to an improvement of grain alignment. The incorporated single crystals help the texture development of the powder via an enhanced stacking of grains and fulfill a role as bypasses of the grain boundaries. This letter highlights the value of quantitative texture analysis to explain the evolution of anisotropic physical properties, as demonstrated here concerning textured thermoelectric materials. (C) 2004 American Institute of Physics.