Abstract
We performed the electrical resistivity and thermoelectric power measurements of the polycrystalline La0.8Ti0.2OBi(S1-xSex)2. The electrical resistivity of La0.8Ti0.2OBi(S0.7Se0.3)2 at room temperature dramatically decreases, and the temperature dependence shows metallic-like behavior. From the electrical resistivity, superconductivity was not observed in La0.8Ti0.2OBi(S1-xSex)2 above 2.8 K. The value of thermoelectric power S(300 K) of La0.8Ti0.2OBiSSe was about -65 μV/K, which is comparable to that of the polycrystalline LaOBiS2. The value of S(300 K) of La0.8Ti0.2OBiS2 was about -115 μV/K. These power factors are relatively smaller than that of the polycrystalline LaOBiSSe.
Highlights
Since the discovery of superconductivity and moderate thermoelectric performance, BiS2-based compounds ROBiS2 (R = La, Ce, Pr, Nd) have attracted much attention.[1,2,3,4,5] The crystal structure is very similar to that of the FeAs-based superconductors, and arises from the stacking of a RO-blocking and BiS2-conducting layer
Superconductivity appears via transition metal Tr4+ substitution at La3+ site in LaOBiS2 (Tr = Ti, Zr, and Hf).[6]
Because the valence of the transition metal is considered to be Tr4+, the replacement of Tr to R-site can be regarded as electron doping, which induces bulk superconductivity
Summary
Superconductivity of the La-based compound LaO0.5F0.5BiS2 is found at T c = 2.6 K by F-substitution to O-site. It is known that chemical pressure is effective in the emergence of bulk superconductivity, and many superconductors are found by Se substitution to the S-site.[7,8,9] In the BiS2-based compounds, both carrier doping and pressure/chemical pressure are needed to generate bulk superconductivity. Measurements of the thermoelectric power are necessary to discover a new candidate of the thermoelectric materials in the BiS2-based compounds. We report the results of transport properties about electrical resistivity and thermoelectric power measurements of the polycrystalline La0.8Ti0.2OBi(S1-xSex)[2], because Tr-doped compound has little information on superconducting and thermoelectric properties
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
