Synthesis of Bi 2 Ge 3 O 9

— We have studied conditions for the preparation of the Bi 2 Ge 3 O 9 compound via accelerated crystallization of a stoichiometric melt and demonstrated the feasibility of acelerated preparation of the Bi 2 Ge 3 O 9 compound from a preprepared amorphous material (glass) by heat treatment in a solid state. Annealing at 670°C or a higher temperature for a short time (30 min) ensures a transition of the amorphous material to stable Bi 2 Ge 3 O 9 (98–99 wt %), with very small amounts of two impurity phases present in the material: metastable ή-Bi 2 GeO 5 and stable Bi 4 Ge 3 O 12 . Raising the annealing temperature to 950°C and increasing the holding time to 360 min ensures a complete transition of the glass to Bi 2 Ge 3 O 9 .