Abstract
The luminescence spectra of the Pr 3+ ion in (La 1− x Pr x) 2O 3 ( x ⩽ 0.2), La 1− x Pr xOF and LiY 1− x Pr xF 4 ( x ⩽ 0.1) powder samples and in LiY 1− x Pr xF 4 ( x ⩽ 0.02) single crystals have been investigated. The concentration quenching of the Pr 3+ emission is observed to be stronger in (La 1− x Pr x) 2O 3. This is ascribed to a more efficient cross-relaxation via superexchange interaction between Pr 3+ ions. This interaction is shown to be effective over longer distances in La 2O 3:Pr than in LiYF 4:Pr (viz. 10 and 5 Å, respectively). The shift of the 4f5d configuration to lower energies with increasing Pr 3+ concentration, which is only observed for (La 1− x Pr x) 2O 3, gives support for this conclusion. Moreover, the vibronic spectra and the vibronic transition probabilities of Pr 3+ in LaOF and La 2O 3 are reported and compared.
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