Concentration effect of cerium in (Y0.9−xGd0.1Cex)2SiO5 blue phosphor

(Y0.9−xGd0.1Cex)2SiO5 with various Ce concentration, x, was prepared by calcination of spray pyrolysis precursor obtained from a mixture of nitrates and TEOS under H2/N2 atmosphere. Cerium could be doped up to 3 at.% into the high-temperature form (X2) of Y2SiO5. The unit cell volume linearly expanded with the x-value. Its structural refinement suggested that the doped Ce3+ ions were almost equally distributed into two kinds of rare earth sites in the X2 phase. The PL spectra showed a peak shift toward significantly longer wavelength (red-shift) with increasing x-value. The PL red-shift might be caused by an energy transfer among the Ce3+ ions distributed in the two sites having slightly different 5d excited energy levels with different coordination numbers.