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© 2018 Elsevier B.V. Photoluminescence of Ce3+- and Pr3+-activated Sr2GeO4powders was measured between 17 and 600 K. For both ions strong 4fn−15dn→4fn(d-f) emission is observed at low temperatures, around 410 nm (Ce3+) and 280 nm (Pr3+). The Ce3+d-f emission quenches starting at 150 K and disappearing completely just above room temperature. Pr3+d-f luminescence shows an onset of quenching also around 150 K and disappears completely between 250 and 300 K. For Pr3+quenching of the d-f emission was connected with an increasing intensity of the3P0luminescence at first and1D2emission at even higher temperatures. Both these 4fn→4fnemissions were observed up to 600 K. Based on the similar quenching temperatures, thermally stimulated photoionization of the 5d electrons from 5d level of Ce3+or Pr3+to the conduction band is proposed as the most probable mechanism for quenching of the d-f emissions.

hree series of nanocrystalline powders ofLu2O3:Eu with Eu concentration varying from 0.05to 13% were prepared. All specimens were obtained through combustionsynthesis using urea or glycine as the fuel. The powders of the firstseries consisted of materials with crystallites about 13 nm in size andwere prepared with urea. For the next series of powders, made withglycine, the crystallites were about 30 nm in size. The powders of thethird series differed from those of the second one in that they wereco-doped with 1% of Ca. For the series made with urea the quantumefficiency was highest for 3% of Eu and never exceeded about 30%. Forglycine-prepared specimens the highest quantum efficiency was about 90%.Without the Ca co-doping such a value could be obtained for specimensdoped with 5% of Eu, while in the series co-doped with Ca 85-90% quantumefficiency could be maintained for all concentrations in the range3-10%. A significant number of OH groups were proved to be left in thefinal product obtained with urea. The low quantum efficiency of thesepowders is attributed to this effect. The results prove that properlyprepared nanocrystalline phosphors can produce luminescence efficiently.

Archaeological ceramics are considered one of the most important sources of both technological and chronological information. Here, the investigation of some archaeological underwater amphorae from the Egadi’s Battle, that decided the end of the First Punic War (241 B.C.), is reported. X-ray Diffraction (XRD), X-ray Fluorescence (XRF), petrography, and Thermoluminescence (TL) were used to determine the composition of the amphorae and to evaluate the compatibly of their age with the above Battle. Considering the historical importance of the act and the well-defined historical collocation these amphorae represent an interesting archaeometric case study.