Synthesis and Crystal Structure of a New Mixed-Valence Terbium Fluoride, KTbIIITbIV2F12, and Related KLnIIIMIV2F12Compounds (MIV=Tb, Zr, Hf;LnIII=Ce–Lu)
1998; Elsevier BV; Volume: 139; Issue: 2 Linguagem: Inglês
10.1006/jssc.1998.7837
ISSN1095-726X
AutoresE. Largeau, Malika El‐Ghozzi, Daniel Avignant,
Tópico(s)Luminescence Properties of Advanced Materials
ResumoDuring a phase relationship study of the system KF–TbF3–TbF4, carried out using X-ray diffraction on samples synthesized under a fluorine atmosphere, a new mixed-valence terbium fluoride, KTb3F12, was brought out. Its crystal structure was determined from single-crystal X-ray diffraction data and refined to a conventionalR=0.031(Rw=0.057) for 920 independent reflections withF>4σ(F). It crystallizes in the tetragonal system with space groupI4/m(No. 87) and unit cell parametersa=7.715(1) Å,c=7.530(1) Å,Z=2. The crystal-structure analysis revealed a perfect ordering between Tb3+and Tb4+cations. The structure is built of chains of edge-sharing [TbF8]4−dodecahedra further linked by [TbF8]5−cubes alternating along the [001] direction with K+ions in 12-coordination. A series of homologous compounds, KLnIIIMIV2F12(MIV=Tb, Zr, Hf;Ln=Ce–Lu), was also evidenced.
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