Correlation between crystal structure and superconductivity in LaO0.5F0.5BiS2

• The LaO0.5F0.5BiS2 superconductor's crystal lattice was tuned by various annealing conditions.
• Superconducting properties were obviously changed by tuning the crystal lattice.
• Superconductivity could be related to the uniaxial strain along the c axis.

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 high-pressure annealing 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.