Fluorite Solid Solutions of Congruent Melting in the PbF2–CdF2–RF3 Systems

• Published in: Crystallography reports Vol. 69; no. 2; pp. 270 - 278
• Main Authors: Buchinskaya, I. I., Fedorov, P. P.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 2024; Springer Nature B.V
• Subjects: Cadmium fluorides; Cations; Crystal Growth; Crystallization; Crystallography and Scattering Methods; Crystals; Erbium; Fluorite; Homogeneity; Low temperature; Melting; Phase composition; Physics; Physics and Astronomy; Rare earth elements; Solid solutions; Terbium; Ytterbium
• ISSN: 1063-7745; 1562-689X
• DOI: 10.1134/S1063774524600182

The congruent melting compositions in the M F 2 – M 'F 2 –RF 3 systems ( M ≠ M ' = Ca, Sr, Cd, Ba, Pb; R are rare-earth elements (REEs)) have been determined based on thermodynamic topological analysis. Crystals of fluorite solid solution in the PbF 2 –CdF 2 – R F 3 ( R = Tb, Ho, Er, Tm, Yb, Lu) systems were grown by the vertical directional crystallization technique. Their phase composition and distribution of components over the crystalline boule length were investigated. Crystals of congruently melting solid solutions (Pb 0.67 Cd 0.33 ) R x F ( R = Tb, Ho, Er, Tm, Yb, Lu) were grown for the first time. Traces of low-temperature transformation—a phase isostructural to the Pb 2 YF 7 compound (sp. gr. I 4/ m ), in which Y sites are occupied by the corresponding R cations and Pb sites can be partially occupied by Cd cations—were found in the crystals with R = Ho, Er, Tm, and Yb. The crystals with R = Tb and Lu have a high degree of homogeneity and are suitable for optical studies.