The Effects of Crystal Field and Temperature on the Photoluminescence Excitation Efficiency of Ce3+ in YAG

Abstract

Absorption and luminescence spectra of YAG:Ce 3+ crystals have been measured at various temperatures between 4.2 ~ and 300~ The high resolution, low temperature spectra show re~olved fine structure. Zero-phonon transitions have been assigned and the phonon replicas correlated with lattice phonon energies. The characteristic absorption band of YAG:Ce 8+ near 460 nm decreases in ]ntensity, whereat that near 340 nm increases~ with increasing temperature. This effect is explained in terms of a tetragonal crystal field splitting of both the 4f 1 ground state and 5d 1 excited states of Ce 8+ in YAG. When allowance is made for changes in the absorption of pump light with temperature the photoluminescence quantum efficiency of Ce z+ in YAG is constant up to 300~ The significance of these crystal field effects for the use of YAG: Ce as a high temperature lamp phosphor is discussed.Ce3+-activated yttrium aluminum garnet (Y3A15012, referred to as YAG) has primarily been developed as a CRT phosphor for flying-spot scanner applications (1, 2). The characteristic Ce 3+ broad-band luminescence in the visible region is now well known, and the phosphor is designated P46 in the JEDEC screen classi-

Trapping states and excited state ionization of the Ce3+ activator in the SrHfO3 host

“…It is extremely difficult to experimentally quantify the scattering losses. On the other hand, the temperature change of absorbance amplitude can be significant, also due to effects like temperature exchange of absorption strengths for 4f-5d 1 and 4f-5d 2 transitions of Ce 3+ as shown in Ce 3+ -doped Y 3 Al 5 O 12 (YAG) crystal [15]. The change in absorbance of 4f-5d 1 transition of Ce 3+ in YAG:Ce between 300 and 500 K becomes more than 25% [16].…”

Local structure of the Ce3+ ion in the yellow emitting phosphor YAG:Ce

“…Despite the fact that this phosphor material was proposed almost 45 years ago [1], and that it has been very thoroughly investigated from the point of view of optical spectroscopy [2][3][4][5][6] and electronic structure [6,7], to the best of our knowledge an experimental investigation of the local structure of the impurity in the garnet structure has never been reported so far. For this reason, we have found it interesting to undertake a detailed study of the location of the Ce3+ ions in YAG using Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy, with the aim of gaining more insight on the spectroscopic behaviour of this valuable material, and to compare the experimental results with the theoretical ones [7,8].…”

Inorganic Phosphor Materials for Lighting

“…However, other phonons rather than those of 131-211 cm -1 could possibly result in non-radiative relaxation via electron-phonon coupling. For example, some phonons of higher vibrational frequency than 200 cm -1 were also found by Robbins [72] to be involved in vibronic transitions in the NUV absorption showing phonon side bands fine structure in both the absorption and emission spectra, adapted from [72] spectrum of YAG:Ce 3? ; however, these are not observed in the luminescence spectrum, probably due to a smearing-out effect caused by multi-phonon couplings in the electronic 4f-5d transitions.…”

“…For the specific case of YAG:Ce 3? , the presence of vibronic transitions is evident from the presence of phonon side bands of the low temperature luminescence spectra [72] as shown in Fig. 12.…”

“…For YAG:Ce 3? , the combined influence of the nephelauxetic effect and ligand-field splitting gives rise to a large redshift, D(A), which makes some of the 3? showing the effect of the centroid shift and ligand field splitting as Ce 3? ions are embedded in YAG, adapted from [39,72]. b The energy level scheme of YAG:Ce 3?…”