In this paper, the
combined effect of gold nanoparticles and high-pressure
densification on the luminescence of Pr3+-doped heavy metal
GeO2–PbO photonic glass was investigated. Localized
states related to ion-trapped exciton defects, S1 and S2, were observed at 342 and 412 nm before densification. After
densification under 7.7 GPa, the structure of the glass host changed
irreversibly, as indicated by the infrared spectrum, refractive index,
and density measurements. Transmission electron microscopy analyses
indicated that the high-pressure densification induced the formation
of clusters of gold nanoparticles. The modifications observed in the
absorption and luminescence spectra of Pr3+ ions in the
VIS–NIR range were associated to the changes in the local field
surrounding the Pr3+ ions in the host glass induced by
high pressure. For excitation at 445 nm (luminescence from 3P2) and 593 nm (luminescence from 1D2), the combined effect of densification and gold nanoparticles induced
an increase in the emission band at 1050 cm–1. For
excitation at 488 nm (luminescence from 3P0),
the combined effect resulted in a strong decrease in the emission
intensities in the VIS, revealing the emergence of nonradiative processes
in resonance with 3P0 state. The observed behavior
was probably due to energy transfer, ion trapped exciton defects,
and cross-relaxation processes among the Pr3+ ions and
gold nanoparticles.