We have prepared polycrystalline [(Ca 1Àx Pb x ) 2 CoO 3:1 ] 0:62 CoO 2 (0 5 x 5 0:03) samples by a conventional solid-state reaction method and investigated the effects of Pb substitution on the thermoelectric and magnetic properties of the samples. With Pb substitution, both electrical resistivity and Seebeck coefficient do not change markedly. This is attributed to the carrier concentration of the samples. Seebeck and Hall coefficient measurements reveal that the major charge carriers in the samples are holes, however, the carrier concentration does not change with increasing x. Neutron powder diffraction and magnetic susceptibility measurements also reveal that Pb ions are in a divalent state in a rock salt-type Ca 2 CoO 3 block layer. The average valence state of Co ions in a CdI 2 -type CoO 2 sheet is 3.1+ and that of Co ions in the block layer is 3.6+. The resulting dimensionless figure of merit for an x ¼ 0:02 sample at room temperature is 0.024, which is approximately equal to the corresponding value of a polycrystalline NaCo 2 O 4 sample.
The behavior of texture formation in AA5182 aluminum alloy was investigated by uniaxial compression tests under strain rates and temperatures ranging from 5:0 Â 10 À4 s À1 to 5:0 Â 10 À2 s À1 and from 673 K to 823 K, respectively. After the deformation, {011} (compression plane) or {001} fiber texture appears. It was found that {001} fiber texture was formed after the development of {011} fiber texture. The size of {001} grains is larger than the average grain size, suggesting that the {001} texture formation is attributed to grain boundary migration. In order to understand the relationship between texture sharpness of {001}, temperature and strain rate, the texture map is proposed. The {001} texture map elucidates that the balance between flow stress and deformation temperature is important for the development of {001} component when the viscous motion of dislocation is the dominant deformation mechanism.
Texture formation of AA5182 for compressive deformation with a range of temperatures from 673K to 823K and strain rates from 5.0×10-4to 5.0×10-2s-1is experimentally investigated by EBSD technique and X-ray diffraction. Fiber textures are observed in all deformation conditions. Stress regions are divided into a low stress region (10~55MPa) and a high stress region (above 55MPa) on the basis of the relationship between stress and grain size. In the low stress region, it is found that the main component of the fiber texture is {001}(compression plane). In this case, the pole density at {001} is increased with increasing temperature at the same stress level. It is concluded that development of {001} component is attributed to grain boundary migration. For the high stress region, the main component of the fiber texture is {011}. It is considered that the formation of {011} component is attributed to the slip deformation by {111}<110> system.
We have prepared polycrystalline specimens of [(Ca 1-x Pb x) 2 CoO 3.1 ] 0.62 CoO 2 (0 ≦ x ≦ 0.03) using the conventional solid-state reaction method, and investigated the Pb substitution effect on the TE properties. With the Pb substitution, both the electrical resistivity and Seebeck coefficient do not change drastically. This is attributed to the carrier concentration. Seebeck and Hall coefficient measurements reveal that the major charge carriers in the samples are holes, however, the carrier concentration does not change drastically with increasing x. The magnetic susceptibility measurements also show that Pb ions take divalent state in the rock salt type [Ca 2 CoO 3 ] block layer. The valence state of Co ions in the CdI 2 type [CoO 2 ] sheet was 3.1+ and that of Co ions in the block layer was 3.6+. The dimensionless figure of merit for the x = 0 sample at room temperature was 0.02, which is approximately equal to the corresponding values of a polycrystalline sample of NaCo 2 O 4 .
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