A New Family of Lithium Rare-Earth Oxyborates, LiLn6O5(BO3)3 (Ln=Pr–Tm): Crystal Structure of the Gadolinium Phase LiGd6O5(BO3)3

✍ Scribed by Jean-Pierre Chaminade; Pierre Gravereau; Veronique Jubera; Claude Fouassier

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 455 KB
• Volume: 146
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1999.8331

✦ Synopsis

A new family of lithium rare earth oxyborates of formula LiLn 6 O 5 (BO 3 ) 3 (Ln ‫؍‬ Pr+Tm) has been discovered in the ternary-phase diagrams Li 2 O+Ln 2 O 3 +B 2 O 3 . Single crystals of LiGd 6 O 5 (BO 3 ) 3 were grown by the 6ux method. The structure of the oxyborate was solved using a data collection with a fourcircle automatic di4ractometer (CAD-4) and with MoK radiation. The cell is monoclinic (space group P2 1 /c, Z ‫؍‬ 4) with a ‫؍‬ 8.489(4) A s , b ‫؍‬ 15.706(3) A s , c ‫؍‬ 12.117(6) A s , ‫,3)2(72.231؍‬ and V‫)1(5911؍‬ A s 3 . Re5nement of 198 parameters using 4402 independent re6ections having intensity I > 3 (I) led to R ‫؍‬ 0.037 (wR ‫؍‬ 0.087). The structure of LiGd 6 O 5 (BO 3 ) 3 can be described as a three-dimensional framework, (Gd 6 O 14 ) 10؊ , of Gd polyhedra connected by common edges and corners, forming cavities where Li and B atoms are inserted. Some oxygen atoms share only Gd polyhedra, justifying the oxyborate label.