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Register a new userSynthesis and Structural details of BiOCu1-xS: Possible new entrant in series of exotic superconductors?
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We report an easy route single step synthesis of BiOCuS with and without Cu deficiency. The title compound is synthesized via solid state reaction route by encapsulation in an evacuated (10-3 Torr) quartz tube. Mixed components of the ingredients in stoichiometric ratio (1/3Bi2O3 +0.34Bi +Cu1-x + S) are pelletized, sealed in evacuated quartz tube and heat treated for 30 hours at 500 0C. Finally the sample is allowed to cool down to room temperature. The resultant compound is black is color and could not hold in pellet form, but is powdered. X-ray diffraction Reitveld analysis is carried out on all three samples of series BiOCu1-xS with x = 0.0, 0.10 and 0.15. These samples crystallize in single phase with space group P4/nmm and with cell parameters as a = 3.868 A and c = 8.557 A for stoichiometric BiOCuS. The volume of the cell slightly increases with an increase in Cu deficiency. The co-ordinate positions are determined by fitting the observed XRD patterns of the studied samples.
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Investigation of isotope effects on superconducting transition temperature (Tc) is one of the useful methods to examine whether electron-phonon interaction is essential for pairing mechanisms. The layered BiCh2-based (Ch: S, Se) superconductor family is a candidate for unconventional superconductors, because unconventional isotope effects have previously been observed in La(O,F)BiSSe and Bi4O4S3. In this study, we investigated the isotope effects of 32S and 34S in the high-pressure phase of (Sr,La)FBiS2, which has a monoclinic crystal structure and a higher Tc of 10 K under high pressures, and observed conventional-type isotope shifts in Tc. The conventional-type isotope effects in the monoclinic phase of (Sr,La)FBiS2 are different from the unconventional isotope effects observed in La(O,F)BiSSe and Bi4O4S3, which have a tetragonal structure. The obtained results suggest that the pairing mechanisms of BiCh2-based superconductors could be switched by a structural-symmetry change in the superconducting layers induced by pressure effects.
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