43 research outputs found
Enhanced thermopower in an intergrowth cobalt oxide LiNaCoO
We report the measurements of thermopower, electrical resistivity and thermal
conductivity in a complex cobalt oxide LiNaCoO, whose
crystal structure can be viewed as an intergrowth of the O3 phase of
LiCoO and the P2 phase of NaCoO along the c axis. The
compound shows large room-temperature thermopower of 180 V/K, which
is substantially higher than those of LiCoO and NaCoO.
The figure of merit for the polycrystalline sample increases rapidly with
increasing temperature, and it achieves nearly 10 K at 300 K,
suggesting that LiNaCoO system is a promising candidate for
thermoelectric applications.Comment: Submitted to AP
CeNiAsO: an antiferromagnetic dense Kondo lattice
A cerium containing pnictide, CeNiAsO, crystallized in the ZrCuSiAs type
structure, has been investigated by measuring transport and magnetic
properties, as well as specific heat. We found that CeNiAsO is an
antiferromagnetic dense Kondo lattice metallic compound with Kondo scale 15 K and shows an enhanced Sommerfeld coefficient of 203
mJ/molK. While no superconductivity can been observed down to 30
mK, Ce ions exhibit two successive antiferromagnetic (AFM) transitions. We
propose that the magnetic moment of Ce ion could align in the G type AFM order
below the first transition at =9.3 K, and it might be modified into the
C type AFM order below a lower transition at =7.3 K. Our results
indicate that the 3 interlayer Kondo interactions play an important role
in Ni-based Ce-containing pnictide.Comment: 13 pages, 5 figures, to appear in J. Phys.: Condens. Matte