Structural analysis and oxygen defects in the partially oxygen-reduced T′-Pr_2-xCe_xCuO_4+δ with x = 0 and 0.15 powders at the normal state

Structural analysis and observation of the oxygen migration of Pr_2-xCe_xCuO_4+δ (PCCO) with Ce-doping concentration, x, of 0 and 0.15 powders are briefly studied through neutron diffraction (ND) patterns and x-ray absorption spectroscopy (XAS) spectrum in the extended x-ray absorption fine structure (EXAFS) range. The PCCO powders are synthesized using the chemical dissolved technique and time-dependent oxygen-reduction annealing in flowing Ar atmosphere. All powders show a stable PCCO phase with tetragonal T′-type crystal structure (space group of I4/mmm) for both the as-prepared and partially oxygen-reduced PCCO powders at room temperature. Occupancy of the apical oxygen, O(3), is detected higher in the doped powders due to Ce-doping effect and generally increases after the shorter-time oxygen-reduction annealing. The decrease of O(3) occupancy is observed for the longer-time reduction annealing process indicating a trace of oxygen migration and recovery of oxygen defect on CuO₂ plane in the T′-structure. This study is essential to elucidate the mechanism of oxygen removal in the electron-doped cuprates.