Synthesis and structure resolution of RbLaF 4

Abstract

The synthesis and structure resolution of RbLaF 4 are described. RbLaF 4 is synthesized by solid-state reaction between RbF and LaF 3 at 425 °C under a nonoxidizing atmosphere. Its crystal structure has been resolved by combining neutron and synchrotron powder diffraction data refinements (Pnma, a = 6.46281(2) Å, b = 3.86498(1) Å, c = 16.17629(4) Å, Z = 4). One-dimensional 87Rb, 139La, and 19F MAS NMR spectra have been recorded and are in agreement with the proposed structural model. Assignment of the 19F resonances is performed on the basis of both 19F- 139La J-coupling multiplet patterns observed in a heteronuclear DQ-filtered J-resolved spectrum and 19F- 87Rb HMQC MAS experiments. DFT calculations of both the 19F isotropic chemical shieldings and the 87Rb, 139La electric field gradient tensors using the GIPAW and PAW methods implemented in the CASTEP code are in good agreement with the experimental values and support the proposed structural model. Finally, the conductivity of RbLaF 4 and luminescence properties of Eu-doped LaRbF 4 are investigated. © 2012 American Chemical Society.