Single crystals of the fluorite nonstoichiometric phase Eu0.9162+Eu0.0843+F2.084 (conductivity, transmission, and hardness)

• Published in: Crystallography reports 2010-07, Vol.55 (4), p.657-661
• Main Authors: Sobolev, B. P., Turkina, T. M., Sorokin, N. I., Karimov, D. N., Komar’kova, O. N., Sulyanova, E. A.
• Format: Article
• Language: English
• Subjects: Crystallography and Scattering Methods; Physical Properties of Crystals; Physics; Physics and Astronomy
• ISSN: 1063-7745; 1562-689X
• DOI: 10.1134/S1063774510040206

The nonstoichiometric phase EuF 2+ x has been obtained via the partial reduction of EuF 3 by elementary Si at 900–1100°C. Eu 0.916 2+ Eu 0.084 3+ F 2.084 (EuF 2.084 ) single crystals have been grown from melt by the Bridgman method in a fluorinating atmosphere. These crystals belong to the CaF 2 structure type (sp. gr. Fm m ) with the cubic lattice parameter a = 5.8287(2) Å, are transparent in the spectral range of 0.5–11.3 μm, and have microhardness H μ = 3.12 ± 0.13 GPa and ionic conductivity σ = 1.4 × 10 −5 S/cm at 400°C with the ion transport activation energy E a = 1.10 ± 0.05 eV. The physicochemical characteristics of the fluorite phases in the EuF 2 − EuF 3 systems are similar to those of the phases in the SrF 2 − EuF 3 and SrF 2 − GdF 3 systems due to the similar lattice parameters of the EuF 2 and SrF 2 components. Europium difluoride supplements the list of fluorite components M F 2 ( M = Ca, Sr, Ba, Cd, Pb), which are crystal matrices for nonstoichiometric (nanostructured) fluoride materials M 1 − x R x F 2 + x ( R are rare earth elements).