Terbium-doped AlO samples were obtained by gas-dispersed synthesis. It was shown that the resulting powders, with particle sizes of 10-70 nm, consist of a mixture of transition aluminas, among which the δ -polymorph is dominant. The luminescence properties of AlO:Tb have been studied upon excitation in the UV-visible range of the spectrum. It was found that Tb ions cause several groups of inhomogeneously broadened emission bands in the range of 470-640 nm, which are characteristic for disordered materials. In addition, the emission spectra contain a broad band at about 450 nm and several narrower ones in the 680-720 nm region. These features are attributed to surface defects and impurity Cr ions occupying Al octahedral positions, respectively.

Single crystals of potassium lanthanum orthophosphate are prepared from high‐temperature melts containing potassium molybdate as a flux and structurally investigated by single‐crystal X‐ray diffraction. The framework is shown to be constructed from isolated LaO7 monocapped prisms and PO4 tetrahedra through corner‐ and edge‐sharing giving rise to 2D sheets with composition [La(PO4)2]3−. Three types of potassium cations reside between these layers. For the solid solutions K3La1−xEux(PO4)2 (x = 0.1–0.9) prepared by the solid‐state route, the excitation and emission luminescence spectra are studied at room temperature. The emission spectra exhibit strong reddish performance, which is due to the 5D0→7FJ transitions of Eu3+ ions. The correlation between the structure and the photoluminescent properties of the phosphors is studied. The energy transfer and concentration quenching of the phosphors are discussed. Solid solutions K3La1−xEux(PO4)2 have a potential application for white‐light‐emitting diodes.

The luminescence of coordination polymers of Pr 3+ , Nd 3+ , and Lu 3+ with tetrafluoroterephthalate and camphorate, [Ln 2 (Fbdc) 3 (DMF) 2 (H 2 O)] 2 (Ln = Pr, Nd, Lu) and [Ln 2 (Camph) 2 (NO 3 ) 2 (MeOH)] 4 (Ln = Pr, Nd, Lu), was studied. Ligand-centered and/or metal-centered emissions appear, which depend on the excitation wavelength, ultimately allowing the emitted light color to be adjusted. Low-efficiency ligand-to-metal energy transfer leads to a difference between the excitation spectra of the tetrafluoroterephthalate- and camphorate-Pr 3+ compounds, arising from a primary filtering effect on the ligand-centered excitation, by Pr 3+ absorption. A secondary inner filter effect significantly changes the shape of the luminescence band, allowing a wide variation in the emission color, producing, for instance, a purple color, which is not the normal spectral emission. The low-efficiency energy transfer renders tetrafluoroterephthalate and camphorate ineffective as traditional “antenna” ligands for Pr 3+ and Nd 3+ .

Tb, Ba). From study of the excitation spectra and the kinetics of luminescence quenching it was concluded that energy is transferred effectively from the Tb 3+ to the Eu 3+ during excitation in the UV and visible regions of the spectrum. Key words: mixed barium-terbium phosphate, Eu 3+ ions, eulitine, luminescent material. In recent years mixed phosphates with the composition M 3 II Ln(PO 4 ) 3 , with M II = Sr 2+ , Ba 2+ and Ln = Y 3+ , Cd 3+ , Tb 3+ , which crystallize in structures of the eulitine type (Bi 4 Si 3 O 12 ), have attracted increased attention on account of their use as the basis of luminophores for white light-emitting diodes [1-4] and plasma display panels [5]. Interest in the material with the composition Ba 3 Tb(PO 4 ) 3 : Eu 3+ arose from the possibility of increasing the luminescence intensity of the Eu 3+ as a result of the sensitizing effect of the Tb 3+ ions [6]. It was shown that the luminescence intensity of the Eu 3+ ions in Ba 3 Tb(PO 4 ) 3 during excitation in the ultraviolet region under vacuum is substantially higher than in Ba 3 Gd(PO 4 ) 3 . In the authors' opinion this is due to more effective energy transfer from Tb 3+ to Eu 3+ than from Gd 3+ to Eu 3+ . It should be noted that in [6] the luminescent characteristics of Eu 3+ in Ba 3 Tb(PO 4 ) 3 were only studied during excitation of luminescence in the vacuum ultraviolet region, which does not make it possible to reach a conclusion about the amount and the microstructure of the Eu 3+ luminescent centers. It is, however, known that compounds with structures of the eulitine type are characterized both by cationic [7] and by anionic (oxygen) disorder. The significant nonuniform broadening of the luminescence bands of the Eu 3+ , Eu 2+ , and Ce 3+ ions in the series of phosphates with the (Ba,Sr) 3 Ln(PO 4 ) 3 composition, where Ln = La 3+ , Eu 3+ , and Lu 3+ , have been linked to these crystal-chemical characteristics [8-10]. On the basis of the similarity in the luminescence spectra of Ce 3+ in a series of compounds with structures of the eulitine type the authors [10] came to the conclusion that the Ce 3+ ions in such structurally ordered systems can even form their own oxygen environment. The authors of [11] undertook a detailed X-ray structural investigation of Ba 3 Tb(PO 4 ) 3 single crystals grown by spontaneous crystallization and by the Czochralski method. It was shown that the Ba and Tb atoms in the Ba 3 Tb(PO 4 ) 3 structure occupy octahedral positions (16c) with distinctly different M-O 0040-5760/15/5103-0191

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