Synthesis and luminescence properties of Mn3+, Bi3+ co-doped Y6WO12 for blue phosphor

Mn 3+ and Bi 3+ co-doped Y 6 WO 12 samples with hexagonal structure were synthesized via an improved salt pyrogenation method at a temperature region of 700–1100 °C for 3 h. In Y 6 WO 12 , Mn 3+ , substituting Y 3+ , occupies a seven-coordination site and its energy levels are treated in near O h symmetry. The samples doped by Mn 3+ alone emit the most intensive blue light at 420 nm under excitation at 247 nm due to charge transition (CT). The mechanism of sensitization of Bi 3+ for Y 6 WO 12 :Mn 3+ was also analyzed by taking account of metal-to-metal charge-transfer (MMCT) from Bi 3+ to Mn 3+ . As a consequence, the phosphor Y 6 WO 12 :Mn 3+ /Bi 3+ can emit blue light under radiation of 370 nm, and the emission intensity is enhanced about five times by the sensitizer Bi 3+ . The optimal doping concentration of Bi 3+ is determined as 1 at% for the emission at 420 nm in Y 6 WO 12 :0.5 at% Mn 3+ phosphors.