M. Faucher et al., A SPECTROSCOPIC STUDY OF THE MONOCLINIC T O TETRAGONAL PHASE-TRANSITION OF THE PHOSPHOR EU3+LIYO2 AT 350 K, Comptes rendus de l'Academie des sciences. Serie 2, Mecanique, physique, chimie, sciences de l'univers, sciences de la terre, 317(12), 1993, pp. 1569-1573
Fluorescence spectra of LiY0.95Eu0.05O2 at 77, 300 and 370 K show evid
ence for a reversible monoclinic to tetragonal phase transition which
occurs at 350 +/- 5 K. The crystal held parameters of Eu3+ determined
in the C-1 and the D-2d sites of europium in the two phases.