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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

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2011

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Vol. 29, No. 4

272--277

EN

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.

2

Optical spectroscopy of the Ho-doped glasses with 3CaO–Ga2O3–3GeO2 composition

Padlyak B. V., Kukliński B., Buchynskii P. P.

Optica Applicata

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2003

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Vol. 33, nr 1

175-181

EN

The UV and visible optical spectra (absorption, emission and luminescence excitation) of the Ho-doped CaO–Ga2O3–GeO2 glasses at room and liquid nitrogen temperatures have been investigated for the first time. The Ho-doped (CHo = 0.7 wt%) glass samples with garnet Ca3Ga2Ge3O12 (or 3CaO–Ga2O3–3GeO2) composition were prepared by the conventional high -temperature synthesis technique. By optical and EPR spectroscopy it has been shown that the holmium impurity is incorporated into the glass network as Ho3+ (4f10, 5I8) ions, exclusively. All transitions of the Ho3+ ions observed in optical spectra of Ho-doped 3CaO–Ga2O3–3GeO2 glasses are identified. The Ho3+ optical absorption spectrum has been analyzed and described in the framework of Judd–Ofelt theory. Optical absorption and emission spectra of the Ho3+ ions in the 3CaO–Ga2O3–3GeO2 glasses are quite similar to Ho3+ optical spectra in other oxide glasses and are characterized by statistical distribution of the local crystal field parameters. Incorporation peculiarities and spectroscopic properties of Ho3+ impurity ions in the glasses of CaO–Ga2O3– GeO2 system are discussed.

3

Spectroscopy and high pressure spectroscopy of the Cr-doped glass materials.

Grinberg M., Borzowska J., Padlyak B., Nowosielski T., Kukliński B., Buchynski P.

Optica Applicata

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2000

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Vol. 30, nr 4

509-516

EN

Optical spectroscopy and high pressure optical spectroscopy of the Cr-doped glasses of CaO-Ga/sub 2/O/sub 3/-GeO/sub 2/ system have been used. The emission spectrum consists of the broad band at about 12700 cm/sup -1/ and the sharper band with maximum peak at 14495 cm/sup -1/ (the R line emission). We have attributed the R line luminescence to the octahedral strong field Cr/sup 3+/ sites in the microcrystallites whereas the broad band luminescence has been related to the chromium in the glassy phase.