Texture development of Ca3Co4O9 thermoelectric oxide by high temperature plastic deformation and its contribution to the improvement in electric conductivity

High temperature uniaxial compression is conducted on Ca3Co4O9 layered cobaltite, in order to achieve a thermoelectric oxide with low resistivity by the development of (001) texture. It is found that flow stress varies depending on deformation temperature and strain rate. Development of a sharp texture having the maximum (001) pole density of about 33 times as high as the random level is achieved. It is found that the high temperature compression process is quite effective for the simultaneous achievement of densification and (001) texture development. It is experimentally confirmed that resistivity decreases drastically by the construction of a sharp (001) texture. (C) 2009 Elsevier B.V. All rights reserved.