Artigo
Crystal structures and luminescence properties of La3Zr4F25 and α-LaZr3F15
Fecha
1998-12-01Registro en:
Journal of Materials Chemistry, v. 8, n. 4, p. 1043-1050, 1998.
0959-9428
10.1039/A708080H
2-s2.0-0003419387
6446047463034654
0000-0003-3286-9440
Autor
CEMES CNRS
Universidade Estadual Paulista (Unesp)
Université Biaise Pascal
Resumen
During a study of the LaF3-ZrF4 system, both La3Zr4F25 and α-LaZr3F15 compounds have been evidenced. Their crystal structures have been determined from single-crystal X-ray diffraction data. La3Zr4F25 crystallises in the cubic system with a = 12.384 Å and 143d space group (no. 220). Its crystal structure is built up of (ZrF6)2- octahedra and (LaF8)5- dodecahedra sharing corners. The low temperature form, α, of LaZr3F15 is orthorhombic (space group Pmmn, no. 59) with a = 15.721 Å, b = 16.299 Å, c = 8.438 Å. Its structure is built of corner-sharing tricaped trigonal prisms surrounding the La3+ ions and both octahedra and monocapped trigonal prisms encompassing the Zr4+ ions. This structure is characterised by dynamically disordered (ZrF6)2- complex anions. The Eu3+ luminescence properties of these phases have been investigated and are discussed in relationship with their crystal structures.