In order to control the orientation distribution of polycrystalline cobaltites with misfit layered structure, thermo-mechanical treatments consisting of high temperature uniaxial compression deformation and heat treatments are examined on Bi_(1.5)Pb_(.5)Sr_(1.7)Y_(0.5)Co_2O_(9-delta) and Ca_3Co_4O_9. The materials were produced by the usual sintering method. High temperature compression deformation was carried out in air at high temperatures where the activation of slip deformation together with the other complementary deformation mechanisms such as grain boundary sliding and dynamic recrystallization are expected. After the deformation, measurements of density, texture and resistivity, and microstructure observation were performed. The density increases by the deformation up to a true strain of-1.0 in both oxides. No further densification was observed by the deformation above -1.0 in strain. The formation of a (001) texture (compression plane) is found after the deformation. The texture sharpens monotonously with an increase in strain. The sharpening continues above -1.0 in true strain, indicating that the texture formation can be attributed to the plastic deformation of the oxides. In some cases the maximum pole density for (001) becomes more than eleven times as high as that of the as sintered material. It is experimentally confirmed that the resistivity can be reduced below one tenth of that of the as sintered material by the densification and the texture development originating from the high temperature compression deformation.
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