1. Synthesis, structural feature and properties of rosiait structure compound BiGeSbO6
- Author
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S.V. Golodukhina, O.M. Gajtko, Roman Svetogorov, A.L. Trigub, Andrey V. Khoroshilov, A. V. Egorysheva, and A. V. Tyurin
- Subjects
010302 applied physics ,Materials science ,Extended X-ray absorption fine structure ,Rietveld refinement ,Band gap ,Process Chemistry and Technology ,Enthalpy ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Gibbs free energy ,Crystallography ,symbols.namesake ,Octahedron ,0103 physical sciences ,Materials Chemistry ,Ceramics and Composites ,symbols ,0210 nano-technology ,Lone pair ,Solid solution - Abstract
The layered oxide BiGeSbO6 has been synthesized for the first time via solid state reaction. Rietveld refinement showed that BiGeSbO6 belongs to PbSb2O6 structural type (P-31m space group) with unit cell parameters a = 5.1314(9), c = 4.9974(1) A, α = 90°, γ = 120°, Z = 1. Using the EXAFS and XANES methods, it was shown that a structural feature of this compound is a strong disordering of the Bi–O octahedron caused by the stereochemical activity of the 6s2 lone pair of Bi3+ electrons. A model according to which one oxygen vertex in the oxygen coordinated Bi3+ octahedron is absent, and the lone pair of electrons builds this polyhedron to the octahedron, was proposed. A particularity of the structure of BiGeSbO6 is that the existing oxygen vacancy does not have a specific position. It was established that BiGeSbO6 does not exhibit any polymorphic transition up until its incongruent melting point Тm = 985°С. Isobaric heat capacity was measured and thermodynamic functions (entropy, enthalpy increment and Gibbs free energy) were calculated for BiGeSbO6 in the 10–1200 K temperature range. We found that the band gap of BiGeSbO6 is due to the allowed direct interband transition with the energy of 3.16 eV. It was shown that BiGeSbO6 has a wide transmission region in the visible and near-IR ranges. BiGeSbO6 is a self-activated phosphor, but its luminescence spectrum is atypical for Bi3+-containing oxides. The luminescent properties of Bi1-xEuxGeSbO6 solid solutions (x = 0.3, 0.5) were also studied.
- Published
- 2020