| Eu3+ doped LiGd(MoO4)2 and KGd(MoO4)2 molybate red phosphors were prepared by solid state reaction method. The phases, excitation spectra and emission spectra were analyzed by XRD and spectrometer. The effects of the sintering temperatures and Eu doping concentration was investigated. Then Sm3+ and Nd3+ doping was tried to improve the luminescence properties.XRD indicated that LiGd(MoO4)2:Eu is scheelite structure and secondary phase was not observed when Eu3+ doped. However KGd(MoO4)2:Eu has similar crystal structure as KGd(MoO4)2, secondary phase was not observed on this powder, too.It indicated that Eu 3+ doped LiGd(MoO4)2 and KGd(MoO4)2 can be excited by 395nm light and 617nm red emission was observed from them. They are match with LED, and are promising to be a new phosphor instead of Eu3+ doped Y2O2S which is the commercial red phosphor now.Influence of low Eu3+ doped concentration on LiGd(MoO4)2:Eu and KGd(MoO4)2:Eu was investigated in detail. It indicated that luminescence properties of LiGd(MoO4)2:Eu are increasing as increased Eu3+ doped concentration, increasing extent reduced when the concentration is above 7%. Fluorescence quenching was not observed on LiGd(MoO4)2 even when the concentration is up to 20%,however, luminescence properties of KGd(MoO4)2:Eu are increasing as increased Eu3+ doped concentration when the concentration is below 9%, fluorescence quenching was observed on KGd(MoO4)2 when the concentration continued increasing.Sm3+ doped KGd(MoO4)2:Eu has a additional exciting peak at 406nm which caused by transition of Sm3+. Sm3+ doping increased the area of excitation spectra of KGd(MoO4)2:Eu which is more suitable for LED. Nd3+ doping caused fluorescence quenching on KGd(MoO4)2:Eu and could not improve any luminescence properties.In this paper, red phosphors of low Eu3+ doped concentration LiGd(MoO4)2 and KGd(MoO4)2 were investigated, which gives the basic theory for development of cheap and efficient red phosphors for white LED. |
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