Structure cristalline du composé RbEu3F10

Crystals of RbEu₃F₁₀ are cubic with a = 11.844 Å, Z = 8, and three possible space groups, $\text{Fm3m, F}\text{4}\text{3m}$, and F432. The structure has been resolved from three-dimensional X-ray data and refined by the least-squares method. The final R values are, respectively, 0.065 and 0.067 for Fm3m and $\text{F}\text{4}\text{3m}$, and are not significantly different. The rare earth symmetry is C_4v for Fm3m and C_2v for $\text{F}\text{4}\text{3m}$. Consequently, we have used the Eu³⁺ ion in the RbEu₃F₁₀ phase as a structural probe in order to state precisely the symmetry of the lanthanide site and distinguish among the possible space groups.