Synthesis and crystal structure of Sr3Bi2O6 and structural change in the strontium-bismuth-oxide system

The crystal structures and their changing trend in the strontium-bismuth-oxide system are critical for the studies of the related systems and their applications. The crystal structure of Sr3Bi2O6 was obtained for the first time in the space group of R (3) over bar with a huge unit cell of a = b = 25.1146(19) angstrom and c = 18.3685(16) angstrom and all bismuth ions are Bi3+ forming [BiO3] trigonal pyramids. Sr3Bi2O6 is a key compound for the structural change trend in the SrO-Bi2O3 binary oxide system at 1000 degrees C. With a decrease in the bismuth content, its valence state changes from +3 to +5 and Bi-O polyhedra changes from connected to isolated before Bi(V) appearance. In the system, the boundary of the solid solution beta-phase (Sr1-xBixO1 vertical bar 0.5x) at 900 degrees C was also determined accurately as 0.770 <= x <= 0.862, experimentally.