The systems Y3-xCexA15012, Ys-~CexA15-zGazO12, and Y3-x-zGdzCexA15012 were studied. It was found that the solid solubility of Ce 3 § in Y3A15012 varies with the atmosphere during firing. Only 2 mole per cent (m/o) of Ce ~ § can be dissolved in the yttrium aluminum garnet in air while almost 6% Ce 3 § enters the garnet lattice when fired at 1450~ under a hydrogen atmosphere. Complete solid solutions were observed in the systems Y3A15Ol~-Gd~A15012 and Y3A15012-Y3GasO12. The cathodoluminescence emission-peak position of the Ce 3 § ion in Y~A15012 host shifted to a longer wavelength while the latttice parameter of the solid solution expanded when Gd 3. ions were substituted for y3 § On the other hand, the emission-peak position shifted to a shorter wavelength when the garnet host contained Ga s § ions in the A13 § position. The lattice parameter of the solid solution increased with Ga concentration. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 169.230.243.252 Downloaded on 2015-03-24 to IP Vol. 120, No. 2 Ce s § ACTIVATED Y3A15Ol~ 281

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Solid solutions in the system YPO4–YVO4, with and without 2 mol% of Tb3, were studied to determine the reason for the total inactivity of Tb in YVO4. The comparison of the diffuse reflectivity of Tb-containing solutions with that of Tb-free ones shows a uv absorption at energies below the absorption edge of YVO4 in materials containing both terbium and vanadium. Selective excitation directly into Tb3+ in these wavelength regions produced reduced Tb3+ emission when there was vanadium present. The band emission of the VO43+ groups, and the Tb3+ emission under electron beam excitation, were strongly quenched whenever terbium and vanadium were both present. Emission of Dy3+, present as a 10-ppm impurity in all samples, was also quenched by the presence of both terbium and vanadium, but not by either alone. All these observations imply energy loss by Tb–V interaction. A particular loss mechanism—the well-known intervalence transfer of charge from Tb to V resulting in an abrupt change of bond strength leading to a transfer of electronic excitation into lattice vibrations—is supported by measurements of Tb activity as a function of V concentration. The intensity of Tb emission is proportionate to the probability that none of four metal ion sites about a Tb is occupied by a V. This suggests the intervalence transfer absorption mechanism because only four of the nearest six metal ion sites have Tb–O–M bond angles (about 150°) consistent with good charge transfer from Tb to V; the remaining two sites have a Tb–O–M near 90° and should be relatively inactive in charge transfer.

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A technique is described which allows for the measurement of the saturation of luminous intensity of phosphors up to high current densities. The actual light intensity profile of the spot is measured and is related to the current density profile across the spot, the latter being obtained from measurements on a nonsaturating phosphor. This technique thus uses a point-bypoint measurement of relative efficiency vs. beam current density, and therefore no assumptions concerning the beam current profile have to be made, and no averaging of beam current over spot diameter is required. Typical data are presented from several classes of materials. For the samples reported, La202S:Tb showed the least degree of saturation, (Zn, Cd)S:Ag the greatest degree, and Zn2SiO4:Mn was intermediate to these two.Most phosphors, when excited by an electron beam, show a less than linear increase in brightness with increasing beam current density. This phenomenon is known as saturation and is indicated schematically in Fig. 1 where both intensity and efficiency are displayed as a function of beam current density. This effect can be particularly troublesome in multicolored cathode ray tubes using high current densities, e.g., post deflection focusing (PDF) type color television tubes. * Electrochemical Society Active Member. ]Key words: luminescence, phosphors, saturation. CURRENT DENSITYFig. 1. Effect of current density on: a) brightness or b) efficiency of a nonlinear phosphor.Two disadvantages will accrue if the phosphors chosen for this type of tube exhibit saturation in the current density range used by the tube: (i) the anticipated brightness increase will not be achieved, and (ii) the color balance and white field produced by color mixings will vary with beam current density. For these reasons, the intensity vs. beam current density data is an important factor in choosing the appropriate phosphors for these types of applications.Measurement of the saturation of various phosphors has been reported by a number of authors (1-6), with the work of Meyer and Palilla (6) being most directly concerned with television tube application. In these previous works, some assumption was made about the current density profile across the electron beam and a calculated average current density was used in the saturation plots. The technique reported in this article determines the actual current density profile of the spot, and so provides a point by point measurement of intensity vs. beam current density. ApparatusPhosphors used in this experiment were either obtained commercially (so designated in the appropriate figures) or prepared in the laboratory. Samples were settled onto 2.5 • 7.5 cm microscope slides using a potassium silicate-barium acetate settling method. After lacquering, the slides were aluminized in a vacuum evaporator. Aluminum deposition was regulated by a quartz crystal thickness monitor such that all samples measured had an aluminum backing of 1000 _ 50A. Saturation measurements were made in a demountable electron beam gun system sho...