Structure cristalline de la phase β-KYb₃F₁₀

Abstract

J. M. ADAMS AND VIJAYALAKSHMI RAMDAS 3227three hydrogen bonds [indeed 0(4) Potassium ytterbium fluoride fl-KYbaF~0 is hexagonal. The unit cell, with a = 8"067 (2), ¢ = 13"203 (4) A, contains four formula units and the space group is P63mc. The crystal structure has been solved from single-crystal diffractometer data by Patterson and Fourier syntheses and refined by a least-squares method with anisotropic temperature factors. The final R value is 0.032 for 789 independent observed reflexions (Rw=0.041). The Yb atoms are surrounded by quadratic antiprisms of F atoms, and three antiprisms share two of their edges to form planar (Yb3FIs) 9-groups. These groups are three-dimensionally linked, but they form four planes which stack, perpendicular to c, in the sequence ABA'B'.The two species of K atoms are surrounded by 15 and 16 F atoms respectively. Bindings between antiprisms and polyhedra are discussed as well as analogies between the structures of KYaF~0, KYb3F~0 and fluorite.

Simplified Description of Complex Structures from Stackings of UGP

“…The low-temperature form of -KYb F (2) is hexagonal (S.G.: P6 mc, a"8.067 (2) A > , c"13.203(4) A > , Z"4) and is based on square antiprisms connected by vertices and edges. The authors noticed the existence of [Yb F ]\ clusters, but their description was based on layers involving only three antiprisms (half of an UOA ).…”

Synthesis, stability and zeolitic behavior of δ­ALn3F10,xH2O and γ­ThLn2F10,H2O phases (Ln = lanthanide)

“…On heating, this phase gives rise to a b hexagonal form at T~769 ³C. 2 This non-reversible transition (not observable by DTA) has been determined by electrical conductivity measurements. 1 For T~952 ³C, a reversible transition is observed leading to a c variety, isotypic to the low temperature form a-KYb 3 F 10 .…”

Structurally based prediction of ferroelectricity in inorganic materials with point group 6mm

“…The atomic coordinates of fl-KYb3F~0 at room temperature, determined by Al~onard, Guitel, Le Fur & Roux (1976), are presented in Table 12. The unit-cell dimensions are a = 8.067 (2), c = 13-203 (4) A.…”