The Copper Ampoule: A New Reactor for the Solid-State Synthesis of Complex Lanthanide Fluorides

For the first time, copper ampoules have been used as reactors for the solid-state synthesis of complex lanthanide fluorides under vacuum. The high ductility of copper allows for high-vacuum tight sealing of the ampoules by cold welding. Furthermore, no chemical reactivity of copper toward solid fluorides has been observed. Thus, for an examination in view of optical upconversion properties, the superstructure phases Ba4-xY3+xF17+x(x0.08) and Pb4xY3±xF17±x(x<0.2) have been synthesized by annealing of mixtures of binary fluorides in evacuated copper ampoules.