Optical spectra of EuP5O14 between 77 and 583 K

The polarized absorption and fluorescence spectra of Eu3+ in a single crystal of EuP5O14 are studied from 77 to 583 K. The energy levels and eigenvectors are presented for septet and qunitet states of Eu3+ in an intermediate coupling scheme. Values of E1 = 6420.08, E2 = 26.12, E3 = 765.93, and zeta = 1290.13 cm-1 are found to give the best overall agreement between the observed and calculated energy levels. The change in spectral structure is observed in the 7F0 to 5D2 absorption spectra at temperatures between 297 and 583 K. This change is attributed to the structural phase transition of the crystal by observing the temperature dependence of degree of polarization and of the oscillator strength of the lines. (author)