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

Abstract

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 R3[combining macron] with a huge unit cell of a = b = 25.1146(19) Å and c = 18.3685(16) Å 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 °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 β-phase (Sr1-xBixO1+0.5x) at 900 °C was also determined accurately as 0.770 ≤ x ≤ 0.862, experimentally.