Platelet crystals of thermoelectric layered cobaltites; pure and Sr-doped [Ca2CoO3]0.62[CoO2]

Single crystal plates (∼5×5×0.1mm3) of pure and Sr-doped [Ca2CoO3]0.62[CoO2] have been grown in a SrCl2 flux. The ratio between the flux and raw materials strongly affected the composition of the grown crystals; that is, Sr ions were doped into the Ca site in the lattice when the flux-rich melt was used. It is found that the Sr-doping suppresses the ferrimagnetic transition temperature and decreases the magnitude of thermoelectric power coefficient, while the valence of Sr2+ ions is equal to that of Ca2+ ions.