Crystalline Li3ThF7 : X-Ray Diffraction and NMR Studies

✍ Scribed by Sandra Helena Pulcinelli; Regina Helena de Almeida Santos; Jean Senegas

• Book ID: 104150679
• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 392 KB
• Volume: 42
• Category: Article
• ISSN: 0022-1139
• DOI: 10.1016/s0022-1139(00)83965-2

✦ Synopsis

A crystal structure determination of Li3ThF7 has been performed on a tetragonal single crystal by X-ray diffraction : a = 6.200 (1) i; c = 12.937 (2) A" ; Z = 4 ; P4/ncc. The structure 1s characterized by layers of monocappeo antiprism IThFgl polyhedra sharing 4 corners in the a,b plane. The lithium atoms are localized between these layers and bridge lThFgl polyhedra along the c-axis. There is a 1:3 disorder of lithium atoms in the Wyckoff sites 8f and 169. NMR studies show that the rapid exchange of the lithium ions between non equivalent sites modulates the electric field gradient seen by individual lithium atoms and can explain the behavior of the 7Li quadrupolar effect observed in crystal11 ne phases. Calculations of the main component of the electric field gradients tensor according to the different sites of the lithium atoms indicate a partial covalent character of the Th-F bond.