Spectroscopic Investigation in Er3+ Doped ZnMoO4 Phosphors

The ZnMoO4 phosphors doped with different concentrations of Er3+ ions have been successfully synthesized by solid state reaction method. The optical properties were studied by frequency upconversion (UC) emission studies. All the prepared phosphors can be effectively excited by 980 nm and exhibit intense peak at similar to 552 nm which lies in green regime. With varying the concentration of Er3+ ions the maximum frequency UC emission intensity has been observed at 0.5 mol% concentrations. In the emission spectra, the UC emission peaks at blue (similar to 489 nm), green (similar to 532 nm, similar to 545 nm and 552 nm) and red (similar to 656 nm and similar to 668 nm) bands are corresponding to the F-4(7/2)-> I-4(15/2), H-2(11/2), S-4(3/2) -> I-4(15/2) and F-4(9/2) -> I-4(15/2) transitions of Er3+ ions. The mechanisms involved in the UC process confirm two photon absorption process which is explored with the help of energy level diagram. The colour of the emitted radiation has been visualized with the help of choromaticity diagram with CIE point (0.31, 0.60) lie in the green colour region. This indicates that the developed Er3+:ZnMoO4 phosphors have suitable applications in NIR to visible upconverter and in making green light display devices.