Improved red to orange ratio (R/O) by co-doping of M+ (M+ = Li, Na, K) in YBO3:Eu3+ nanophosphors

YBO3:Eu3+ particles are used as Red emitter in plasma display panels (PDPs) and a possible new generation of Hg-free fluorescent lamps, due to their high vacuum ultraviolet (VUV) absorbency and extraordinarily high luminescent efficiency under VUV excitation. Still, it needs to get high Red to Orange ratio (R/O) because Eu3+ has main emission transitions (5D0→7F1, magnetic dipole) at 590 nm (Orange) and (5D0→7F2, electric dipole) at 612 nm (Red). High R/O ratio can be obtained by change of synthesis method and co-doping so that crystal field environment of Eu3+ will be altered. In this work, nano phosphors of YBO3:Eu3+ (7 at.%) and co-doped with various univalent metal ions, M+ (= Li, Na and K (1 at.%)) were prepared by a simple chemical route. XRD patterns of all the prepared samples are indexed to the hexagonal structure. The average crystallite sizes are found to be in range 14-17 nm. Upon M+ co-doping, there is slight decrease in crystallite size, which may change in luminescence properties