Realizing enhanced downconversion photoluminescence and high color purity in Dy3+ doped MgTiO3 phosphor in presence of Li+ ion

The Dy3+, Li+ co-doped MgTiO3 phosphor has been successfully synthesized through a high temperature solid state reaction method. The structural measurement suggests that the doping of Li+ ion improves the crystallinity and particles size of the phosphor. The EDS measurement approves the presence of Mg, Ti, O and Dy elements in the phosphor. The FTIR measurement reveals the presence of different vibrating molecules in the phosphor. The optical band gap of the phosphor slightly decreases in presence of Li+ ion. The photoluminescence excitation spectrum of Dy3+ doped phosphor shows a strong band centered at 355 nm alongwith other weak bands. The Dy3+ doped phosphor gives intense yellow photoluminescence centered at 579 nm due to F-4(9/2) -> H-6(13/2) transition on excitations with 327, 355, 367 and 385 nm wavelengths. However, the emission intensity is relatively larger for 355 nm excitation. The emission intensity of phosphor varies on increasing concentrations of Dy3+ ions and it is optimum at 2 mol%. Interestingly, the emission intensity of the phosphor is enhanced up to 3 times in presence of Li+ ion. This is due to an increase in crystallinity, particles size and charge compensation induced by the Li+ ion. The CIE coordinates show the presence of emitted light with high color purity in the yellow region of visible spectrum. The lifetime of Dy3+ level in the phosphor is found to increase via doping of Li+ ion. Thus, the Dy3+, Li+ co-doped MgTiO3 phosphor may be a useful candidate in displays devices and white light emitting devices (WLEDs).