A Single Layer Epitaxial Garnet White Phosphor.

The co-emission of [EQ]Pr sup 3+[EN] and [EQ]Tb sup 3+[EN] in the [EQ]Y sub 3 Al sub 5 O sub 12[EN] host has allowed the production of a single layer white emission phosphor for use in high resolution CRT displays. Strong line emissions at 488 and 610 nm from [EQ]Pr sup 3+[EN] are complemented by the 387, 420, and 544 nm emission form [EQ]Tb sup 3+[EN] to yield a white phosphor. The performance of Y3Al5O12 phosphor at high power density electron beam excitation has been observed to be 0.24X of the Y2885Ce0015Tb01Al5O12 garnet phosphor. For operation at low power density excitation, a better performance is observed with 0.41X of the luminescence of Y2885Ce0015Tb01Al5O12. This latter performance translates into an internal conversion efficiency of 4.3%. Growth of the phosphor by liquid phase epitaxy from a PbOB2O3 flux in a multiple wafer fixture has been examined for preparation of low defect density CRT faceplates. As grown one face has a density of about 3 per [EQ]cm sup 2[EN], but by polishing off this face a CRT faceplate with a very low defect density is possible. This epitaxial film phosphor should have application to the small format but high resolution displays which are viewed directly by the observer, and thus do not require high image brightness.