V. P. Dotsenko

Synthesis and luminescence properties of Eu2+-doped Li2SrSiO4

We have studied the luminescence spectra of Li2Sr1 − xEuxSiO4 (x = 0.0001–0.01) solid solutions prepared by solid-state reactions and a sol-gel process in a reducing atmosphere. The spectra show a broad band in the range 500–700 nm, centered at 578 nm, which is due to the 4f65d → 4f7 transition. The luminescence excitation spectrum shows, in addition to bands due to Eu2+ 4f7 → 4f65d transitions, a strong band centered at 174 nm, attributable to absorption in the SiO44− group.

Ln2+ stabilization in strontium borates

The effect of crystal structure on the stability of Ln2+ ions in strontium borates has been studied by luminescence spectroscopy. The results indicate that the stability of Ln2+ in strontium borates depends on the nature of the borate anions surrounding it and the effectiveness of the compensation of the charge on Ln3+, which can be quantified by the formal volume per oxygen atom, VO, in the structure of the borate.

Luminescence of calcium orthoborate doped by Ce3+ ions

The luminescence properties of calcium orthoborate Ca3(BO3)2 doped with cerium are studied upon x-ray (∼30 keV) and VUV (3.5–15 eV) synchrotron excitation. The emission bands peaked at 392 and 420 nm are attributed to interconfigurational transitions of Ce3+ ions. The short-wavelength emission band at 340 nm is caused by radiative decay of exciton-like states. The fundamental absorption edge of Ca3(BO3)2 is found to be near 7.1 eV. Based on thermoluminescence data and other information, the behavior of defects in Ca3(BO3)2:Ce3+ is studied.

Luminescent properties and stability of europium ions in Ca2BO3Cl:Eu

We have studied the luminescent properties of Eu2+ and Eu3+ in the calcium chloride borate Ca2BO3Cl under optical and synchrotron excitation. The results demonstrate that a reductant should be present during synthesis in order to stabilize Eu2+ in Ca2BO3Cl and provide insight into the factors responsible for the long-wavelength position of the luminescence band (λmax = 577 nm) and the relatively low Eu2+ stability in Ca2BO3Cl.

Synthesis and luminescence examination of β-NaCaPO4:Eu2+, phosphor promising for white light-emitting diode applications

The morphology, particle-size distribution, and luminescence properties of β-NaCaPO4:Eu2+ were examined in relation to the synthesis conditions by electron-microscopic, X-ray phase, and luminescence analyses. The distribution of the Eu ions over the metal sites in the β-NaCaPO4 structure was analyzed.

Metal-Centered Photoluminescence of Eu3+ and Tb3+ Coordination Polymers with Dianions of Camphoric and Tetrafluoroterephthalic Acids

It was shown that coordination polymers [Ln(Camph)(NO3)(MeOH)2]n (1Ln, Ln – Eu, Tb; Camph2––camphorate dianion) and [Ln2(tFbdc)3(DMF)2(H2O)2]n (2Ln, Ln – Eu, Tb; tFbdc2–– tetrafluoroterephtalate dianion) possess metal-centered emission with quantum yields up to 40% under UV-irradiation. It was found that tetrafluoroterephtalate dianion is better antenna ligand than camphorate dianion. It was assumed that for studied complexes the vibrational radiationless deactivation of excited states of ligands influence more significantly on the luminescence characteristics than energy of triplet states of ligands.

Luminescence study of nanosized Al2O3:Tb3+ obtained by gas-dispersed synthesis

Terbium-doped Al2O3 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 Al2O3:Tb3+ have been studied upon excitation in the UV-visible range of the spectrum. It was found that Tb3+ 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 Cr3+ ions occupying Al3+ octahedral positions, respectively.

Structure and Luminescent Characteristics of Ba3Tb(PO4)3 Doped with Eu3+ Ions

It was shown that, unlike the series of phosphates with the compositionM3Ln(PO4)3 (M2+ = Ca, Sr, Ba; Ln3+ = Eu and others) with structures of the eulitine type, characterized by cationic disordering, the luminescence spectra of Ba3Tb(PO4)3 doped with Eu3+ ions depend significantly on the excitation wavelength. This arises from localization of the Eu3+ ions in the Ba3Tb(PO4)3 matrix at two nonequivalent crystallographic positions (Tb, Ba). From study of the excitation spectra and the kinetics of luminescence quenching it was concluded that energy is transferred effectively from the Tb3+ to the Eu3+ during excitation in the UV and visible regions of the spectrum.

The influence of viscous media on the nonradiative deactivation of the luminescence of Eu3+ and Tb3+ complexes with acyl-2-aminobenzoic acids

Using the example of europium and terbium complexes with acyl-2-aminobenzoic acids, it is shown that the nonradiative losses of excitation energy in solutions of water-soluble polymers can be decreased both due to the coordination of lanthanide ions with oxygen-containing functional groups of polymers and due to the viscosity formed by them, which reduces molecular diffusion.