The fluorescence of a number of new Ce3+-activated phosphors is described and discussed. Only host lattices with a sublattice consisting of trivalent lanthanide ions are used to avoid charge compensation of the Ce3+ ion. Usually the Ce3+ emission is in the near-ultraviolet region. Y3Al5O12–Ce and SrY2O4–Ce, however, show emission in the visible region with a maximum in the green. Conditions for visible Ce3+ emission are indicated, viz., large crystal-field splittings (Y3Al5O12–Ce) or a large Stokes shift (SrY2O4–Ce). In a number of cases we were able to observe all crystal-field components of the excited 5d level of Ce3+. The cubic crystal-field splitting of the 5d level varies strongly with host lattice from 7000 to 14 000 cm−1. The position of the center of the 5d levels in oxides is about 30% lower than in the free ion. For some phosphors we observed more than one emission band at room temperature. This is due to fluorescence from higher excited levels. Efficient energy transfer from Ce3+ to Cr3+ was observed in Y3Al5O12.

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The fluorescence of Y3Al5O12–Ce3+ under cathode-ray excitation consists of an emission band peaking at 550 nm. The decay time is 0.07–0.08 μsec. In view of these properties this phosphor is very suitable for flying-spot cathoderay tubes for color television.