V. Chornii

Electronic structure and VUV spectroscopy of bismuth-containing phosphate-tungstate crystals

The origin of intrinsic luminescence and mechanisms of excitation energy transfer in undoped K₂Bi(WO₄)(PO₄) and K_6.5Bi_2.5W₄P₆O₃₄ crystals are revealed in complex experimental and computational studies. The photoluminescence (PL) properties are studied under the VUV synchrotron excitations. The electronic structures of the crystals are calculated using the FLAPW method. Calculations indicate different character of the density of electronic states in the lower parts of the Conduction bands of K₂Bi(WO₄)(PO₄) and K_6.5Bi_2.5W₄P₆O₃₄. The PL emission spectra of K₂Bi(WO₄)(PO₄) and K_6.5Bi_2.5W₄P₆O₃₄ reveal wide bands peaking near 540 and 620 nm respectively. The PL in both compounds is effectively excited in 3.7 - 8 eV region of excitation energies.

Synthesis, electronic structure and VUV spectroscopy of K 2 BiZr(PO 4 ) 3 Crystals

The polycrystalline samples of K₂BiZr(PO₄)₃ were synthesized by spontaneous crystallization method. The photoluminescence (PL) spectroscopy studies of K₂BiZr(PO₄)₃ are carried out under the VUV synchrotron excitations. The electronic structure of K₂BiZr(PO₄)₃ is calculated by the FLAPW method. The PL spectra of K₂BiZr(PO₄)₃ reveal two main components in the UV and visible spectral regions (peaking near 3.6 and 2.6 eV respectively). It is assumed that the UV PL component of K₂BiZr(PO₄)₃ originates from transitions in ZrO₆ polyhedra, while the visible one is related to Bi³⁺ ions in oxygen coordination.

VUV spectroscopy and electronic structure of Al(PO 3 ) 3 crystals

The photoluminescence properties of undoped Al(PO₃)₃ crystals synthesized by flux method are studied under VUV synchrotron excitations. The electronic structure of Al(PO₃)₃ crystals is calculated by the FLAPW method. The PL emission spectra of Al(PO₃)₃ reveal emission bands in the violet and in the yellow-red spectral regions. Obtained results point to an active role of the electronic states of phosphate groups in the processes of intrinsic luminescence in Al(PO₃)₃ crystals.

Synthesis and luminescence of Cr(III)-doped aluminum oxide/molybdate composites

The conditions of synthesis and luminescence characteristics of composites Al₂O₃:Cr³⁺/NaAl(MoO₄)₂:Cr³⁺ obtained from molybdate high-temperature solutions have been studied. The influence of the impurity Cr³⁺ ions on crystallization regions in the molten system Na-Al-Mo-O has been detected as a key factor of composite formation. The luminescence emission spectra of the composite exhibit two narrow lines at 692 nm (Al₂O₃:Cr³⁺) and 740.5 nm (NaAl(MoO₄)₂:Cr³⁺), which indicates that both components of the composite are doped with chromium.

Crystal structure and luminescence of layered perovskites Sr 3 LnB III SnO 8 (B III = Sc, In)

The Sr₃LnInSnO₈ (Ln = La, Pr, Nd) and Sr₃LaScSnO₈ perovskites were synthesized and their structures have been determined by X-ray powder diffraction. The peculiarities of the structures and correlations composition - structure - luminescent properties have been discussed.

Synthesis, structure and luminescence properties of KBi(MoO 4 ) 2 :Eu 3+

Solid solutions KBi(MoO₄)₂:Eu³⁺ have been prepared by solid state synthesis and characterized by powder X-ray diffraction. The structure of KBi(MoO₄)₂ represents 3D framework built up from MoO₄ and BiO₈ species, while potassium cation has been found to share one position with bismuth.

Electronic structure and luminescence mechanisms in M I M III (MoO 4 ) 2 molybdates

The mechanisms of intrinsic luminescence in several molybdate crystals of M^IM^III(MoO<inf>4</inf>)<inf>2</inf> (M^I = Li, Na, K; M^III =Bi, Y, Fe) type are revealed in complex experimental and theoretical studies. The luminescence spectroscopy studies under VUV synchrotron excitations are applied together with the electronic structure calculations carried out by the FLAPW method. Simultaneous analysis of diffuse reflectance and luminescence excitation spectra is used for determination of the energy gap (Eg) values of the crystals. It is found that the molybdate groups MoO<inf>4</inf>2− play dominant role in the processes of intrinsic luminescence in studied molybdate compounds.