[Synthesis and photoluminescence of Zn(1-x) Mo(1-y)Si(y)O4 : Eu+ phosphor]

The phosphors Zn(1-x) Mo(1-y)Si(y)O4 : Eu(x)3+ (0.05 < or = x < or = 0.30, 0 < or = y < or = 0.09) were prepared by solid state reaction technique at 800 degrees C. The powder X-ray diffraction patterns of the samples show that the phosphors are of single phase and the doping Eu ion and Si ion have little influence on the host structure. The effects of flux and calcination temperature on the luminescent properties of the phosphors were investigated. The results showed that flux content has effects on the luminescent properties, and the optimized flux content and the best calcination temperature is 4% and 800 degrees C, respectively. The presence of the Na+ ion strengthens the photoluminescence intensity of the phosphors. The addition of Na+ ions balanced the charge in samples, enhanced the luminescence intensity of samples, and the luminescence intensity reached the maximum when the doping concentration of Na2 CO3 was 4 Wt%. The luminescent properties of Zn0.80 Mo(1-y)Si(y)O4 : Eu(0.20)3+ were studied by the excitation and emission spectra, and the influence of Eu3+ and Si4+ concentrations on the luminescent property was discussed. As the calcination temperature rises from 700 to 800 degrees C, the emission intensity increases due to the improvement of crystallinity. The excitation spectra consist of a broad band and a series of narrow lines, and the narrow lines are attributed to the intrinsic transition from 7FJ (J = 1-4) to 5DJ (J = 0, 1) of Eu3+. It was found that the PL emission intensity was enhanced with the increase in the Eu3+ doping ratio and reached a maximum value at x = 0.20. The result indicated that Zn(1-x)Mo(1-y)Si(y)O4 : Eu(x)3+ phosphors can be excited effectively at 393 and 464 nm light. The presence of the Si4+ ion strengthens the photoluminescence intensity of the phosphors and the strong red emission lines at 616 nm correspond to the forced electric dipole 5D0 --> F2 transitions on Eu3+. Compared with Y2O2S : 0.05 Eu3+, the obtained Zn0.80Mo0.97Si0.03O4 : Eu(0.20)3+ phosphor shows an enhanced red emission under 393 nm excitation and the emission intensity of Y2O2S : 0.05Eu3+ is only 50% of that of Zn0.80Mo0.97Si0.03O4 : Eu(0.20)3+. The optical properties suggest that Zn0.80Mo0.97Si0.03O4 : Eu(0.20)3+ is an efficient red emitting phosphor for light emitting diode (LED) applications.