Facile Synthesis of Bastnaesite-Type LaF[CO3] and Its Thermal Decomposition to LaOF for Bulk and Eu3+-Doped Samples

Rare-earth metal(III) oxide fluorides with the composition MOF (M = La-Lu) seem to offer promising host lattices for luminescence applications by doping these materials with trivalent lanthanoid cations. Unfortunately, there was no simple and practicable way to synthesize the compounds in phase-pure quality with classical solid-state chemistry reactions. However, by using the rare-earth metal(III) fluoride oxo-carbonates, MF[CO3], as solution-born precursor materials that crystallize with a bastnaesite-type structure, easy access is now possible by mild thermal decomposition. Synthetic details, investigations on the phase purity and the presence of the oxocarbonate anion [CO3](2-) proved by IR measurements as well as from X-ray powder diffraction data are given in this paper for the example of bulk LaF[CO3] and Eu3+-doped samples. The latter (LaF|CO3}:Eu3+) shows a bright orange-red luminescence that is stronger than that of the product of its thermal decomposition: trimorphic LaOF:Eu3+. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)