Luminescence of the europium(3+) ion in zirconium(4+) compounds

Abstract

The luminescence of the Eu3+ ion in some Zr4+ compounds is reported in order to study the influence of the effectively negative charge of the Eu3+ ion on the quantum efficiency for charge-transfer excitation.This effectively negative charge of the Eu3+ ion does not in principle enhance radiationless relaxation rates in the excited charge-transfer state, but the presence of vacancies in the structure may lower the efficiency considerably. For the Eu3+ luminescence in Zr02 and ZrPzO, the quantum efficiencies amount to about 30% and 60%, respectively. In these compounds the presence of vacancies may account for these values. In LizZr03:Eu3+ with a relatively low Li+ concentration it seems as though the partial incorporation of the Eu3+ ions on a Li+ site accounts for the low efficiency (about 10% at room temperature). The incorporation of the Mg2+ ion as a charge compensator in the LizZro3 lattice increases the quantum efficiency up to at least 60%.

Synthesis and photoluminescence of Eu2+ by co-doping Eu3+ and Cl− in Sr2P2O7 under air atmosphere

“…Yet, this reduction has not been reported in the case of singly Eu 3+ doped ␣-Sr 2 P 2 O 7 . van der Voort [20] and Doat [21] reported that the solubility of Eu 3+ ions in pyrophosphate is limited and even at a small quantity of doped Eu 3+ a second EuPO 4 phase would be observed. The problem hinder the reduction from Eu 3+ to Eu 2+ in air is that Eu 3+ cannot easily enter into the ␣-Sr 2 P 2 O 7 host and substitute the Sr 2+ .…”

Structural and optical properties of europium doped zirconia single crystals fibers grown by laser floating zone

“…41,42 The CT bands, also of interconfigurational nature, involve for instance the promotion of the ligand electrons to the metal ion and usually occur in the UV region. 24,[41][42][43][44] For the case of Eu 3+ in oxide hosts, the promotion of an electron from a ground state configuration 4f 6 to the lowest 4f 5 5d level occurs in the UV and vacuum UV spectral region. [41][42][43][44] On the other hand, the CT transitions are known to occur at longer wavelengths than the f -d transitions and their peak positions are known to decrease in energy with larger average distance of the surrounding anions.…”

“…5͒ correspond to two different CT transitions as also detected in other zircon based compounds. 24 Considering the relative intensity of the absorption bands in the PLE spectra, the Eu 3+ luminescence from the 5 D 0 level is preferentially populated by CT mechanisms rather than the intra-4f 6 Eu 3+ excited levels. A comparison between the PL spectra obtained with excitation in the CT region and in the intra-4f 6 excited states ͑above the 5 D 2 level͒ can be observed in Figs.…”

“…In fact, the visible and infrared transitions of several lanthanide ions in bulk, microstructured, and nanostructured zirconia polymorphs processed by different routes have been exploited by different research groups for potential applications as solid state lighting and displays. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Indeed, associated with the high energy bandgap, the low phonon energy resulting from the small stretching frequency ͑470 cm −1 ͒ exhibited by ZrO 2 foresees a high yield of the intra-4f n transitions from the RE doped zirconia, [14][15][16][21][22][23][24][25] a suitable host material for optical applications such as optical active waveguides.…”

Heterovalent Zr4+-Cu2+ substitution in zirconium pyrophosphate: From theoretical models to synthesis and utilization

“…Zirconium(IV) pyrophosphate, ZrP 2 O 7 , represents a technologically important material, which has already found its application as high temperature proton conductor [1,2], catalyst [3], a host for luminescence materials [4][5][6], dielectric material [7], high density refractory [8,9] and ceramic with unique thermal expansion properties [10][11][12]. Despite the high attention to the ZrP 2 O 7 phase, there are only a few reports on heterovalent substitutions in its structure.…”