HIGH-PRESSURE FLUORESCENCE LINE NARROWING OF EU(III)-DOPED SODIUM DISILICATE GLASS

High-pressure fluorescence line narrowing (HPFLN) has been used to cha racterize the local structure of Eu3+ ions in sodium disilicate glass up to 210 kbar. HPFLN spectra, measured at 77 K, were analyzed using c rystal-field theory. As pressure was increased from ambient to approxi mately 40 kbar, a redshift of me D-5(0)<--F-7(0) excitation band was a ccompanied by a simultaneous decrease in the Eu3+ site crystal-field s trength and a lengthening of the fluorescence lifetime from approximat ely 2.3 to 2.4 ms. These trends were reversed above 40 kbar, as crysta l-field strength increased with pressure and lifetime decreased linear ly to approximately 1.4 ms at 210 kbar. The D-5(0)<--F-7(0) excitation band broadened significantly above 70 kbar and continued to shift red above 150 kbar. HPFLN results are interpreted in terms of structural changes in the silicate glass matrix and compression of the Eu3+ bondi ng environment. Lifetime and intensity changes are attributed to a pre ssure induced increase in the electron-phonon coupling to local vibrat ions. Pressure-induced crystal-field effects are used to deduce charac teristics of high- and low-crystal-field-strength sites in ambient pre ssure glasses. Spectral and lifetime results for the sample released f rom high pressure show that a new local Eu3+ structure is formed durin g decompression.