Improved Single Crystal Growth of the Boron Sillenite “Bi24B2O39” and Investigation of the Crystal Structure

✍ Scribed by M. Burianek; P. Held; M. Mühlberg

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 253 KB
• Volume: 37
• Category: Article
• ISSN: 0232-1300
• DOI: 10.1002/1521-4079(200208)37:8<785::aid-crat785>3.0.co;2-r

✦ Synopsis

Improved Single Crystal Growth of the Boron Sillenite "Bi 24 B 2 O 39 " and Investigation of the Crystal Structure

The boron sillenite, up to now known as the 12:1 compound Bi 24 B 2 O 39 in the system Bi 2 O 3 -B 2 O 3 and crystallizing in the space group I23, melts incongruently at 655 °C only about 25 K above the eutectic tie line and corresponding to a steep liquidus line. Single crystals with dimensions larger then 1 cm 3 have been successfully grown in [100], [110], and [111] direction by an improved Top Seeded Solution Growth (TSSG) technique equipped with crucible weighing, accelerated crystal rotation technique and air-cooled pulling rod. The structure of the boron sillenite was analyzed by X-ray diffraction method, which was possible due to the high crystalline quality achieved. A defect-free sublattice corresponding to a Bi-O framework is isostructural with all sillenites, but a 2 Å environment around the origin is occupied by different cations with different population coefficients. The best calculation results in the formula Bi 24.5 BO 38.25 which is more Bi-rich than the 12:1 assumption.