Hexametavanadates M4+M2+(VO3)6: Thermal stability and luminescent characteristics |
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| Authors: | B. V. Slobodin L. L. Surat B. V. Shulgin A. N. Cherepanov A. V. Ishchenko R. F. Samigullina F. G. Neshov |
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| Affiliation: | 1.Institute of Solid-State Chemistry, Ural Division,Russian Academy of Sciences,Yekaterinburg,Russia;2.Ural State Technical University,Yekaterinburg,Russia |
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| Abstract: | Rhombohedral hexametavanadates K4Sr(VO3)6, K4Ba(VO3)6, Rb4 Ba(VO3)6, and Cs4Ba(VO3)6 melt incongruently in the temperature range of 491 to 600°C. Cooling of peritectic melts yields mixtures of compounds typical of M2+O-M2+O-V2O5 systems, far from equilibrium and depending on the cooling kinetics. The vanadate Cs4Ba(VO3)6 undergoes reversible polymorphic transformation at 360°C. All compounds show broad-band luminescence with a maximum of the luminescence spectrum at 490–590 nm with three types of excitation. The vanadates K4Sr(VO3)6 and Rb4Ba(VO3)6 show the highest luminescence intensity at room temperature. The latter is also most efficient at liquid nitrogen temperatures. The luminescence spectra depend on the excitation of vanadates. Three hypotheses were put forward to interpret this finding. The nature of luminescence is attributed to the relaxation of electronic excitation in [VO4]3− structural tetrahedra present in the vanadates. The performance characteristics of luminophores were determined. These luminophores may be promising as X-ray luminescent screens, radioluminescence indicators, and light-emitting diode devices. |
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