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The luminescent properties of Eu 3+ and Eu 2+ ions in sodium pyrophosphate, Na 4 P 2 O 7 , have been studied. The excitation spectrum of the Eu 3+ emission in Na 4 P 2 O 7 consists of several sets of bands in the range 280-535 nm due to 4f-4f transitions of Eu 3+ ions and a broad band with a maximum at about 240 nm interpreted to be due to a charge transfer (CT) transition from oxygen 2p states to empty states of the Eu 3+ 4f 6 -configuration. Although the CT band energy is large enough, the quantum efficiency (η) of the Eu 3+ emission in Na 4 P 2 O 7 under CT excitation was estimated to be very low (η ≤ 0.01). In terms of a configurational coordinate model, this fact is interpreted as a result of the high efficiency of a radiationless relaxation from the CT state to the 7 F 0 ground state of Eu 3+ ions occupying sodium sites in Na 4 P 2 O 7 . A strong reducing agent is required in order to stabilize Eu 2+ ions in Na 4 P 2 O 7 during the synthesis. Several nonequivalent Eu 2+ luminescence centers in Na 4 P 2 O 7 were found. Keywords: sodium pyrophosphate, Eu 3+ and Eu 2+ ions, luminescence, quantum efficiency.Introduction. Luminescence of lanthanide ions in alkali-metal phosphates has not been reported despite the comparatively large number of publications on the latter. Such information seems useful for interpreting the luminescent properties of lanthanide ions in double alkali and alkaline-earth phosphates of general formula M

Synthesis and Luminescent Study of Ce 3+ -Doped Terbium-Yttrium AluminumGarnet. -Polycrystalline samples of (Tb0.8Y0.2)3(1-x)Ce3xAl5O12 (x = 0-0.03) are prepared by solid state reaction of Al2O3 and mixed rare earth oxides (Tb,Y)4O7:Ce (about 1300°C, 3-5 h). The products are characterized by XRD, SEM, and emission and excitation spectroscopy. Substitution of Tb 3+ for Y 3+ in the garnet structure results in broadening of the emission band and a shift of its maximum towards longer wavelengths. The excitation spectra for the Ce 3+ emission contain broad bands at 6.73 and about 9.5 eV in addition to the 4f n →4f n-1 5d excitation bands of Ce 3+ and Tb 3+ . -(DOTSENKO*, V. P.; BEREZOVSKAYA, I. V.; ZUBAR, E. V.; EFRYUSHINA, N. P.; POLETAEV, N. I.; DOROSHENKO, Y. A.; STRYGANYUK, G. B.; VOLOSHINOVSKII, A. S.; J. Alloys Compd. 550 (2013) 159-163,