Detection of oxide-ion and oxygen vacancy swapping via upconversion luminescence in La2Mo2O9:Yb3+, Er3+

摘要

It is requisite to detect thermally activated oxide-ion motion in oxide- ion conductors via an in situ non-contact method when applied in solid oxide fuel cells, oxygen sensors and oxygen separation. This research conceptually proposes an alternative approach by using the upconversion (UC) luminescence of Yb3+-Er3+ in La2Mo2O9 oxide- ion conductors. According to the results, the temperature-dependent UC luminescence intensity ratio of H-2(11/2) -> I-4(15/2) to F-4(9/2) -> I-4(15/2) transitions of Er3+ can reveal the activation process of oxide- ion and oxygen vacancy swapping at 150-200 degrees C in alpha-La2Mo2O9, which has a break point in the plot. It is also evidenced and confirmed by the temperature-dependent UC decay curves, temperature-dependent alternating current (AC) impedance data, temperature-dependent internal friction data and temperature-dependent Raman data. The analysis according to Judd-Ofelt theory supports this point as well. This research may promote new applications of luminescence, and offer an alternative approach to design novel multifunctional materials.