title: Trigonal structures of ABe2BO3F2 (A = Rb, Cs, Tl) crystals.
abstract: Several interesting fluoroberyllium borates were synthesized hydrothermally and characterized by single-crystal X-ray diffraction. The crystal structures of RbBe(2)BO(3)F(2) (RBBF; rubidium fluoroberyllium borate) and CsBe(2)BO(3)F(2) (CBBF; caesium fluoroberyllium borate), previously determined in the space group C2, were reinvestigated for higher symmetry and found to have more suitable solutions in the space group R32. TlBe(2)BO(3)F(2) (TBBF; thallium fluoroberyllium borate) was synthesized as a novel compound also having this trigonal structure type. Details of the space-group determination and unique structural features are discussed. These crystal structures were compared with that of KBe(2)BO(3)F(2), revealing interesting structural trends within this family of compounds that are also discussed. A crystallographic explanation of the physical morphology is postulated.
authors.affiliation: Department of Chemistry and Center for Optical Materials Science and Engineering Technologies, Clemson University, Clemson, SC 29634, USA.
authors.forename: Colin D
authors.initials: CD
authors.lastname: McMillen
authors.forename: Jia
authors.initials: J
authors.lastname: Hu
authors.forename: Donald
authors.initials: D
authors.lastname: VanDerveer
authors.forename: Joseph W
authors.initials: JW
authors.lastname: Kolis