The copper ampoule: A new reactor for the solid-state synthesis of complexlanthanide fluorides

For the first time, copper ampoules have been used as reactors for the soli d-state synthesis of complex lanthanide fluorides under vacuum. The high du ctility of copper allows for high-vacuum tight sealing of the ampoules by c old welding. Furthermore, no chemical reactivity of copper toward solid flu orides has been observed, Thus, for an examination in view of optical upcon version properties, the superstructure phases Ba4-xY3+xF17+x (x approximate to 0.08) and Pb4+/-xY3+/-xF17+/-x (x less than or equal to 0.2) have been synthesized by annealing of mixtures of binary fluorides in evacuated coppe r ampoules. (C) 1999 Academic Press.