Glasses containing nominally 1, 2, 5, and 10 wt% Sm2O3 in Na2O-Al2O3-SiO2 and Al2O3-SiO2 were prepared from metal alkoxide solution using the sol-gel process. After low temperature heat treatment in air, the glasses were heated up to 800 °C under a flowing H2 atmosphere to reduce Sm3+ into Sm2+. Samarium ions in the divalent and trivalent states were identified by fluorescence measurements. The fluorescence properties of Sm2+ions are discussed in relation to concentration of Sm2O3 and the glass matrix composition. Preliminary results of pressure studies on the luminescence spectra and lifetime of Sm2+ in the glasses are presented as well.

High pressure is used to tune the emission and band structure of the phosphors Ce3+:Lu2S3 and Ce3+:Lu2SiO5. A significant red shift of the broad 5d → 4f emission of Ce3+ was observed in both phosphors. In Ce3+:Lu2S3, we also observed a significant decrease in the emission intensity of Ce3+ and attribute the quenching to a pressure-induced electronic crossover of the Lu2S3 conduction bandedge with the emitting 5d state of Ce3+. In Ce3+:Lu2SiO5, two Ce3+ sites are present and we observed energy transfer from one site (Ce(2)) to the other (Ce(1)) at low pressure. At high pressure, the energy transfer ceases and emission is no longer observed from the Ce(1) site. We propose an exciton recombination model of the energy transfer process.

We report the results of high pressure luminescence studies of the emission of Mn2+ in bulk Zn0.55Ga0.30S up to ∼214 kbar, bulk ZnS up to ∼184 kbar, and nanocrystalline ZnS (∼8 nm particle sizes) up to ∼300 kbar. We observed a strong redshift with pressure (-30(3) cm−1/kbar) for the 4T1→6A1 emission transition of Mn2+ in all three systems. We also observed emission quenching at high pressure in all three systems and attribute the quenching to a pressure induced phase change of the ZnS host lattice to a rocksalt (NaCl) phase.

Deposition of a rare earth salt layer on a silicon substrate with subsequent spark processing yields a porous Si layer and SiO 2 cap doped with the rare earth ion. We have characterized luminescent Er-doped porous SiO2 on Si by scanning electron microscopy, energy dispersive Xray spectroscopy, as well as visible and near IR photoluminescence (PL) spectroscopies. Energydispersive x-ray maps indicate that the erbium concentration in the porous layer can be controlled by varying the molarity of the erbium solution deposited on the substrate prior to spark processing. Visible PL measurements reveal that the concentration of Er3+ is proportional to the resultant intensity of the visible fluorescence transitions; however, for the near IR fluorescence peak at 1.54 gim, self-quenching due to erbium clustering occurs at higher concentrations. Erbium-doped porous silicon layers can also be obtained by diffusion of an erbium salt into porous silicon formed by anodic etching of Si in hydrofluoric acid. Densification of the porous Si layers through high temperature oxidation after erbium diffusion forms erbium-doped SiO2 layers.

The effect of pressure on the spectrum and energy transfer properties of Cr3+:Tm3+:YAG has been considered. The results of cw and pulsed luminescence experiments are reported. The high pressure cw experiments demonstrate the existence of 1G4 → 3H5 emission from Tm3+. We believe this emission is also present in Tm3+:YAG at ambient pressure and has been previously misassigned. High pressure pulsed luminescence studies indicate a lengthening of the lifetime of Cr3+ in Cr3+:Tm3+.YAG and indicate that the rate of energy transfer from Cr3+ to Tm3+ decreases with increasing pressure. We interpret this result in terms of a destabilization of the 4T2 level of Cr3+ with increasing pressure.