Crystal Growth and Optical Properties of the Polar Hydrated Pentaborates Rb[B5O6(OH)4] . 2H2O and NH4[B5O6(OH)4] . 2H2O and Structure Redetermination of the Ammonium Compound

✍ Scribed by P. Becker; P. Held; L. Bohatý

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 260 KB
• Volume: 35
• Category: Article
• ISSN: 0232-1300
• DOI: 10.1002/1521-4079(200011)35:11/12<1251::aid-crat1251>3.0.co;2-c

✦ Synopsis

Large single crystals of the polar, hydrated pentaborates Me[B 5 O 6 (OH) 4 ]•2H 2 O (Me = Rb, NH 4 ) were grown from aqueous solutions. The structure of NH 4 [B 5 O 6 (OH) 4 ]•2H 2 O was redetermined and proved to be orthorhombic (space group Aba2 (No. 41) with a = 11.3192(7) Å, b = 11.0261(8) Å, c = 9.2316(5) Å, V = 1152.2(1) Å 3 , D x = 1.569 Mgm -3 , Z = 4, M = 272.15 gmol -1 , R(F) = 0.0369 for 1266 unique reflections (I ≥ 4σ (I)), isomorphous with the potassium and rubidium compounds. Refractive indices between 365 nm and 1100 nm as well as unpolarized absorption spectra of NH 4 [B 5 O 6 (OH) 4 ]•2H 2 O and Rb[B 5 O 6 (OH) 4 ]•2H 2 O were determined and phase-matching curves for second-harmonic generation were calculated. Both compounds allow type I and type II phase-matching at wavelengths from about 450 nm to the near infrared region.