We have systematically investigated the crystal structure, magnetic susceptibility, and electrical resistivity of the BiS 2 -based superconductor

We have systematically investigated the crystal structure and the magnetic properties of BiS 2 -based superconductor Ce 1-x Nd x O 1-y F y BiS 2 (x = 0 -1.0, y = 0.3 , 0.5 and 0.7) and Nd 1-z Sm z O 1-y F y BiS 2 (x = 0 -0.8, y = 0.3 , 0.5 and 0.7) . In the REOBiS 2 system, both crystal structure and physical properties are tunable by substituting with the different RE (RE = rare earth) elements, having a different ionic radius, such as Ce, Nd and Sm.In the Ce 1-x Nd x O 1-y F y BiS 2 system, bulk superconductivity is observed for

We have investigated the thermoelectric properties of the novel layered bismuth chalcogenides LaOBiS2-xSex. The partial substitution of S by Se produced the enhancement of electrical conductivity (metallic characteristics) in LaOBiS2-xSex. The power factor largely increased with increasing Se concentration. The highest power factor was 4.5 W/cmK 2 at around 470 ºC for LaOBiS1.2Se0.8. The obtained dimensionless figure-of-merit (ZT) was 0.17 at around 470 ºC in LaOBiS1.2Se0.8.

Correlation between crystal structure and superconducting properties of the BiS2-based superconductor LaO0.5F0.5BiS2 was investigated. We have prepared LaO0.5F0.5BiS2 polycrystalline samples with various lattice constants. It was found that the annealing the sample under high pressure generated uniaxial strain along the c axis. Further, the highly-strained sample showed higher superconducting properties.We concluded that the uniaxial strain along the c axis was positively linked with the enhancement of superconductivity in the LaO1-xFxBiS2 system.

We have investigated the high-temperature thermoelectric properties of the layered compound LaO1-xFxBiS2. The electrical resistivity of LaOBiS2 showed an anomalous behavior; a metal-semiconductor transition was observed around 270 K. It was found that the value of the electrical resistivity decreased with F substitution. The Seebeck coefficient decreased with increasing F concentration. The highest power factor of 1.9 µW/cmK 2 at 480 ºC was obtained for LaOBiS2.