Luminescence performance of yttrium-stabilized zirconia ceramics doped with Eu3+ ions fabricated by Spark Plasma Sintering technique

Yttrium stabilized zirconia (YSZ) ceramics doped with Eu³⁺ ions have been successfully fabricated by Spark Plasma Sintering (SPS) technique. The influence of the europium concentration and post-annealing process on the structural, optical, and luminescent properties of the ceramics has been studied. It is shown that an increase in the europium concentration from 0.1 to 3 wt% does not lead to significant changes in the transmission spectra. However, annealing in air atmosphere at temperature from 700 °C to 1300 °C significantly affects the transmission spectrum, as a possible consequenceofthe formation of oxygen vacancy defects. The analysis of the photoexcitation and photoluminescence spectra showed that the main excitation bands are determined by direct excitation of the ⁷F₀ ground state of Eu³⁺ions to the higher 4f energy levels with further radiation transitionsfrom these states. Moreover, the europium ion in the obtained ceramics occupy low-symmetry sites without inversion center.The luminescence decay kineticsare described by a doubleexponential function with decay time τ₁ ~ 20 ns and τ₂~ 90 ns for intrinsic emission centers and millisecond (τ ~ 1.4 ms) for Eu³⁺emission, for all investigated ceramics. The luminescence spectra in nanosecond time region are characteristic for yttrium-stabilized zirconia and are caused by oxygen vacancies in the presence of heavy cations (Y³⁺ and Eu³⁺).