Modulation of the optical properties of Pr³⁺-doped Y₂O₃ ceramics by Zr doping

Abstract

The photoluminescence properties of 0.2% Pr³⁺-doped (Y_1–0.01xZr_0.01x)₂O₃, (x = 0, 0.1, 1, 3, 4.5, 6) ceramics were investigated. The luminescence intensity due to the transition from the ³P₀ level increased drastically when the Zr content x increased, which is completely quenched in Y₂O₃:Pr³⁺ (x = 0) due to the thermal relaxation through the lowest 5d level of the Pr³⁺ ion. By monitoring at 630 nm (¹D₂→³H₄), we found that the 4f–5d photoluminescence excitation bands for Pr³⁺ in the two six-fold sites [C₂ and S₆ in the Y₂O₃:Pr³⁺ (x = 0)] were observed at approximately 300 and 340 nm. On the other hand, when monitored at 510 nm (³P₀→³H₄), the Zr-doped samples showed an additional 4f–5d band at 280 nm. Based on these results, we concluded that the ³P₀ luminescence is from Pr³⁺ in a seven-fold site, which is generated by incorporation of an additional oxygen via a defect chemical reaction, $2\text{ZrO}_2 \xrightarrow{\text{Y}_2 \text{O}_3} 2\text{Zr}_\text{Y}^ \bullet + \text{O}_\text{i}^{\text{\prime\prime}} + 3\text{O}_\text{O}^\text{x} $.