Photoluminescence properties of $Eu3+$ and $Bi3+$ in $YBO3$ host under vacuum ultraviolet/ultraviolet excitation

The photoluminescence properties of $Bi3+/Eu3+$ doped $YBO3$ phosphors under 147, 168, 185, 222, and 262 nm excitation were studied in this paper. The sensitization luminescence of $Eu3+$ by $Bi3+$ was demonstrated and a useful concentration scope, which is $0.05–0.25mol%$⁠, for $Bi3+$ doped into $YBO3:Eu3+$ as candidate of plasma display panel red phosphor was optimized. The relative emission intensity of $Bi3+$ ions occupying $C3$ sites in $YBO3$ crystal increases gradually with $Bi3+$ concentration increasing, while the emission of $Bi3+$ occupying $S6$ sites decreases because of energy transfer from $S6$ sites to $C3$ sites. The peak of emission band changes from 295 to 320 nm as $Bi3+$ concentration increases from 0.1 to $0.25mol%$⁠. Therefore, $0.25mol%$ is the critical concentration for $Bi3+$ ions to transfer their absorption energy between different sites at room temperature. As a result, the luminescence of $YBO3:Bi3+$⁠, $Eu3+$ decreases as $Bi3+$ concentration increases further.