nic structures , and photoluminescence properties of an e ffi cient and thermally stable red-emitting phosphor Ca 3 ZrSi 2 O 9 : Eu 3 + , Bi 3 + for deep UV-LEDs

A series of red-emitting Ca3ZrSi2O9:Eu ,xBi phosphors was synthesized using a conventional high temperature solid-state reaction method, for the purpose of promoting the emission efficiency of Eu in a Ca3ZrSi2O9 host. The site preference of Bi 3+ and Eu in the Ca3ZrSi2O9 host was evaluated by formation energy. The effects of Bi on electronic structure, luminescent properties, and related mechanisms were investigated. The inner quantum yield of the optimized sample increased to 72.9% (x 1⁄4 0.08) from 34.6% (x 1⁄4 0) at 300 nm ultraviolet light excitation. The optimized sample (x 1⁄4 0.08) also showed excellent thermal stability, and typically, 84.2% of the initial emission intensity was maintained when the temperature increased to 150 C from 25 C, which is much higher than that without Bi doping (70.1%). The mechanisms of emission properties and thermal stability enhancement, as well as the redshift of the charge transfer band (CTB) induced by Bi doping in the Ca3ZrSi2O9:Eu 3+ phosphor, were discussed. This study elucidates the photoluminescence properties of Bi-doped Ca3ZrSi2O9:Eu 3+