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1 Materials Science Poland

1 2011

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Characterization of various Eu2+ sites in Ca2SiO4:Eu2+ and Ba2SiO4:Eu2+ by high-pressure spectroscopy

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

Materials Science Poland

2011

Vol. 29, No. 4

272--277

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 b - Ca2SiO4:Eu2+ phase, whereas the emission peaked at 610 nm - to the g - 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 b - Ba2SiO4 phase.