  High-quality superconducting KxFeySe2 single crystals were synthesized using
an easy one-step method. Detailed annealing studies were performed to make
clear the phase formation process in KxFeySe2. Compatible observations were
found in temperature-dependent X-ray diffraction patterns, back-scattered
electron images and corresponding electromagnetic properties, which proved that
good superconductivity performance was close related to the microstructure of
superconducting component. Analysis based on the scaling behavior of flux
pinning force indicated that the dominant pinning mechanism was delta(Tc)
pinning and independent of connectivity. The annealing dynamics studies were
also performed, which manifested that the humps in temperature-dependent
resistance (RT) curves were induced by competition between the
metallic/superconducting and the semiconducting/insulating phases.
