Investigation of Some Ce3+-Activated Phosphors

Abstract

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.

Ce and La Single- and Double-Substitutional Defects in Yttrium Aluminum Garnet: First-Principles Study

“…12 Optically active Ce 3+ impurities are known to substitute for Y 3+ at D 2 (c) sites. 1,9 These sites are also occupied by inactive Lu 3+ , Gd 3+ , and La 3+ red shift inducing impurities 5,9,13 , whereas Ga 3+ and In 3+ blue shift leading impurities substitute for Al 3+ ions. 5 A necessary condition in order to understand the factors that govern how the Ce:YAG luminescence depends on codoping and, ultimately, to be able to control the color of the Ce:YAG: phosphor via codoping, is to acquire a detailed knowledge of the local structures of the double or multiple substitutional defects at the atomistic level, as well as of their electronic structures.…”

Structural effects and4f−5dtransition shifts induced by La codoping in Ce-doped yttrium aluminum garnet: First-principles study

“…1,2 Controlling the color of these devices is considered one of the important issues governing the success of these technologies 3 and one of the methods used for this purpose is codoping. [4][5][6][7] Codopants are long ago known to be able to act as co-activators 6 and as wavelength shifters.…”

Crystal chemistry of BaCa2Ln6O12 (Ln  In, Sc, Y, Dy, Ho, Er, Tm, Yb, Lu) and luminescence of europium- and terbium-activated BaCa2Y6O12

“…The energy difference between the two maxima is about 5000 cm-'. This corresponds to the value reported for the difference between the spin-allowed and spin-forbidden 4f75d transition [27]. In view of the results obtained with europium-activated BaCazY 6O i2, it is also possible that these two excitation bands correspond to excitation of Tb3+ ions on two different sites.…”

“…5D4 -+ 7F5 intensity ratio, it can be concluded that the site on which the Tb3+ ion is substituted possesses no inversion symmetry [27]. Incorporation on the Bai site (point symmetry S,) can thus be excluded.…”