Preparation and Crystal Structure Analysis of Ba2BiGa11O20

✍ Scribed by T.R. Wagner; T.J. Styranec

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 398 KB
• Volume: 138
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1998.7790

✦ Synopsis

X-ray structure investigations of ternary BaO-Ga 2 O 3 crystals grown in a Bi 2 O 3 flux led to discovery of a quaternary compound of ideal composition Ba 2 BiGa 11 O 20 . Single-crystal X-ray diffraction indicates a monoclinic unit cell with parameters a ‫؍‬ 14.9283(14) A s , b ‫؍‬ 11.7046(8) A s , c ‫؍‬ 5.1170(5) A s , and ‫؍‬ 91.137(7)°. The structure is similar to that of Ba 3 TiAl 10 O 20 and related compounds. Three different refinement trials were completed, involving different treatments of positioning of bismuth or gallium atoms shifted from normal barium and gallium sites. The refinement selected as representing the best model has only one bismuth atom positioned near a barium site at a displacement of 0.495 A > . A crystal chemical analysis based on the X-ray data suggests that the displacement of bismuth atoms is due to the stereochemical activity of the 6s 2 lone pair. X-ray refinement was carried out by full-matrix least squares on F 2 on all data, to give R 1 ‫؍‬ 0.0689 and wR 2 ‫؍‬ 0.1802 for 104 parameters and 1361 independent reflections. The final position assignments were analyzed via bond valence sum calculations.