Abstract
The fluorescence of in has been investigated using laser-excited site-selection spectroscopy. Four different crystal-field sites, denoted as Eu(1), Eu(2), Eu(3), and Eu(4) have been detected and optically characterized through their corresponding magnetic-dipole emission transitions. The local symmetry of the ions in these sites deviates slightly from the main symmetry as a consequence of distortions perpendicular to the c ferroelectric axis. The relative concentrations of these sites have been studied as a function of the [Li]/[Nb] concentration ratio. It is suggested that the formation of ()-() pairs is responsible for the major Eu(3) and Eu(4) sites, while the Eu(1) and Eu(2) sites correspond to ions in lattice positions but perturbed by different charge-compensating defects. The effect of codoping with ions has also been investigated; the same sites as in the singly doped system are present, although the Eu(1) site is strongly enhanced in relation to the others.
- Received 17 June 1992
DOI:https://doi.org/10.1103/PhysRevB.47.88
©1993 American Physical Society