Hydrothermal Syntheses and Crystal Structure of NH4Ln3F10 (Ln=Dy, Ho, Y, Er, Tm)

✍ Scribed by Z.J. Kang; Y.X. Wang; F.T. You; J.H. Lin

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 420 KB
• Volume: 158
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.2001.9131

✦ Synopsis

Ammonium rare earth 6uorides NH 4 Ln 3 F 10 (Ln ‫؍‬ Dy, Ho, Y, Er, Tm) were synthesized by a hydrothermal method. Two polymorphs, of the hexagonal -KYb 3 F 10 and the cubic -KYb 3 F 10 structure types, were formed under hydrothermal conditions for most of the rare earth 6uorides except NH 4 Dy 3 F 10 , for which only the cubic -phase was obtained. The crystal structures of MLn 3 F 10 (M ‫؍‬ alkaline metal, NH ؉ 4 and Ln ‫؍‬ rare earth) show a strong correlation to the ratio of ionic radii (R M /R Ln ), which has been expressed in a structure phase diagram of the ionic radii of univalent and rare earth cations.