Synthesis of IR phosphors based on germanatoborate Gd 14 Ge 2 B 6 O 34

Processes of the formation of germanatoborates Gd 14 B 6 Ge 2 O 34 and Gd 13.02 Nd 0.98 B 6 Ge 2 O 34 have been studied using different methods of synthesis (solid-state interaction, direct and inverse co-precipitation, self-propagating high-temperature synthesis (SHS)). It has been established that the synthesis of germanatoborates Gd 14 B 6 Ge 2 O 34 and Gd 13.02 Nd 0.98 B 6 Ge 2 O 34 using the inverse precipitation and SHS methods occurs with the formation of an intermediate apatite-like phase, which upon heating to above 1100°С is reconstructed into the Ln 14 B 6 Ge 2 O 34 (Ln = Gd, Nd) structure. The germanatoborates synthesized crystallize in the trigonal system (space group P 3 1 ). The lattice parameters of Gd 13.02 Nd 0.98 B 6 Ge 2 O 34 are a = 9.746(4) Å and c = 25.795(13) Å. The thermal stability of the Gd 14 B 6 Ge 2 O 34 and Gd 13.02 Nd 0.98 B 6 Ge 2 O 34 germanatoborates has been studied. The obtained materials of composition Gd 13.02 Nd 0.98 B 6 Ge 2 O 34 show luminescence properties and can be employed as infrared phosphors.