Phonon vibrations and photoluminescence emissions and their correlations with the electrical properties in Er3+ doped Bi3YO6 oxide-ion conductors

The phonon variations, photoluminescence emission and electrical properties were systematically studied in Er3+ doped Bi3YO6 (Bi3Y1−xErxO6) oxide-ion conductors. The unit cell parameters (a and V) undergo a first increase and subsequent decrease trend with x, which is attributed to the fluctuations of the O occupation at 48i site. Five fundamental and new phonon mode splitting by Er3+ were observed by reflective FT-IR Reflectance spectroscopy, suggesting the locally structural distortion associated with the Er3+ octahedral occupancy. The Bi3Y1−xErxO6 ceramics of x = 0.2 exhibits the most intensive photoluminescence emission and a smallest activation energy of 1.1 eV. The high oxide-ion conductivity (>0.02 S/cm at 600 °C) was achieved, which can rival the most studied Yttria-stabilized zirconia (YSZ) system. The conductivities for all the Bi3Y1−xErxO6 ceramics present a curvature above 550 °C and a sudden decrease at x = 0.4. These changes in the conductivity were described intern of lattice vibrations for given oxide-ion systems.