Search Results

You are looking at 1 - 2 of 2 items for

  • Author: M. Grinberg x
Clear All Modify Search
Open access

M. Grinberg, J. Barzowska, A. Baran and B. Kukliński

Abstract

Photoluminescence of Ba2SiO4 and Ca2SiO4 activated with Eu2+ was investigated at various temperatures (from 10 K to 300 K) and pressures (from ambient to 200 kbar). At ambient pressure and room temperature, under UV excitation both phosphors yielded a green emission band with maxima at 505 nm and 510 nm for Ba2SiO4 and Ca2SiO4, respectively. The energies of these bands depended on pressure; the pressure shifts were −12:55 cm−1/kbar for Ba2SiO4:Eu2+; and −5:59 cm−1/kbar for Ca2SiO4:Eu2+. In the case of Ca2SiO4:Eu2+, we observed additional broadband emission at lower energies with a maximum at 610 nm (orange band). The orange and green emission in Ca2SiO4:Eu2+ had different excitation spectra: the green band could be excited at wavelengths shorter than 470 nm, whereas the orange band — at wavelengths shorter than 520 nm. The pressure caused a red shift of orange emission of 7.83 cm−1/kbar. The emission peaked at 510 nm was attributed to the 4f65d→4f7(8S7=2) transition of Eu2+ in the β — Ca2SiO4:Eu2+ phase, whereas the emission peaked at 610 nm — to the γ — Ca2SiO4:Eu2+ phase. The emission of Ba2SiO4:Eu2+ peaked at 505 nm was attributed to the 4f65d→ 4f7(8S7/2) transition of Eu2+ in the β — Ba2SiO4 phase.

Open access

T. Pawlik, D. Michalik, J. Barzowska, K. Szczodrowski, T. Lesniewski, M. Sopicka-Lizer and M. Grinberg

Abstract

This paper presents the results of the synthesis temperature on the properties of the ceramic powders of SrSi2O2N2:Eu2+ obtained by the solid-phase reaction. Synthesis was carried out in the temperature range of 1250-1650°C for 2 hours in nitrogen flow in the reducing atmosphere of the graphite furnace. The phases present in the resultant powders were identified by X-ray structural analysis (XRD). Scanning electron microscopy (SEM) was used to examine the changes in the powder morphology as a result of the synthesis. The excitation and emission spectra measurements let to study phosphor photoluminescence properties. The results show the strong influence of temperature synthesis on the formation and purity of expected phases. The synthesis temperature also affects the luminescent properties of SrSi2O2N2:Eu2+ ceramic powders.