Abstract: The PDP phosphor, LT-GdBO₃:Eu, was prepared by a sol-gel process. Some conventional experiments, such as XRD,
Raman spectrum, and photoluminescence spectra, were given to study its crystal structure and optical properties. When a dye laser system was used, emissions
from ⁵D₀ levels of Eu³⁺ ions at two different sites were easily distinguished. The site symmetries were analyzed by the emission spectra,
and factors that affectted the energy transfer were also investigated. When the sol-gel sample was sintered at 1100℃, a phase transition to the Vaterite-type
GdBO₃ occured, with an absorption of heat which was mainly caused by the realignment of the lattice. The sol-gel samples had quite strong luminescent
intensity. And, at the same time, the quenching concentration was as high as 20mol%.

Key words: PDP phosphor, rare earth borates, site selective excitation, phase transition, concentration quenching