β-Sr10Ga6O19: an oxygen deficient perovskite containing [Ga6O19]-polyanions

摘要: Abstract A novel modification of hexagallium decastrontium oxide, β -Sr 10 Ga 6 O 19 , has been prepared from a non-stoichiometric melt composition 4SrO : 2 3 in the temperature range between 1490 to 1600 °C. The crystal structure was determined at 25 °C single X-ray diffraction data (orthorhombic, space group Pbcn =34.3163(21) A, b =7.8918(4) c =15.9558(7) A, V =4321.1(4) A Z =8, R 1 =0.036, wR =0.076 for 1839 observed reflections with I >2 σ ( )). It contains highly puckered unbranched six-membered oligogroups [Ga ] 20− . oligomers are located 6.5 A wide slabs oriented perpendicular [0 0 1] and connected via Sr-ions residing within as well slabs. Alternatively, can be described 8×2×4 superstructure perovskite AB 20.8% vacancies oxygen sublattice. From 64 B -sites unit cell 25% occupied by Sr- 75% Ga-cations, whereas corresponding exclusively Sr. Therefore, relationship expressed following chemical formula: Sr(Ga 3/4 Sr 1/4 )(O 19/8 □ 5/8 ).