Synthesis and characterisation of CaMoO_4:Eu~(3+), Eu~(3+)/Sm~(3+), Eu~(3+)/Sm~(3+)/Li~+ red phosphor for white LED

摘要

A series of molybdate red emitting phosphors have been successfully synthesised at 800°C by coprecipitation method. The excitation spectra of the phosphors reveal three strong excitation bands at 395,466 and 535 nm respectively, which match well with the near UV and blue light emitting diode chips. The intensity of the emission from ~5D ->~7F_2 of Ca_(0.75-x)MoO_4 : Eu_(0.25)~(3+),Sm_X~(3+) phosphors with the optimal compositions of x=O04 is 1-3 times higher than that of Ca_(0.75)MoO_4 : Eu_(0.25)~(3+). The photoluminescence of Ca_(0.5)MoO_4 : Eu_(0.25)~(3+), Sm_(0.25)~(3+) (M=Li, Na, K) phosphors show the stronger emission band at 616 nm than that of Cao-75Mo04 : Eu^, but the intensity decline with the M+ ion radius increased. In addition, the thermal quenching characteristics of CaMoO_4:Eu~(3+), Eu~(3+)/Sm~(3+), Eu~(3+)/Sm~(3+)/Li~+ are also investigated under the temperature from 40 to 200°C, and the relative luminous intensity attenuation rate is the lowest and the thermal stability is better by doping Eu~(3+)/ Sm~(3+)/Li~+, indicating that CaMoO_4:Eu~(3+)/Sm~(3+)/Li~+ are more promising red emitting phosphors.