The thermoelectric properties of [Ca2CoO3]0.62[CoO2] textured ceramics

Large and high-quality single crystal flakes of [Ca
₂
CoO
₃
]
_0.62
[CoO
₂
] compound were grown from Co
₃
O
₄
and CaCO
₃
reagents with chloride flux. Typical single crystal flake size is about 5times5times0.02 mm
³
. Obtained crystal flakes were consolidated by the spark plasma sintering (SPS) technique at 1100 K for 1 h. Grain alignment was checked by XRD and also was confirmed by SEM observations on the fractured surface. At 1000 K electrical conductivity of the textured ceramics is about 270 Scm
^-1
, twice as higher than that of powder sample sintered by the SPS procedure. ZT value of the textured sample reaches 0.4 at 1000 K, being 50% improvement relative to the powder-sintered sample, though thermal conductivity increases simultaneously