Magnetic resonance and structural study of the cluster fluoride Nb6F15

• Published in: Physica. B, Condensed matter Vol. 381; no. 1-2; pp. 47 - 52
• Main Authors: KNOLL, R, SOKOLOVSKI, J, BENHAIM, Y, SHAMES, A. I, GOREN, S. D, SHAKED, H, THEPOT, J.-Y, PERRIN, C, CORDIER, S
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier 01-05-2006
• Subjects: Antiferromagnetics; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Magnetic properties and materials; Magnetic resonances and relaxations in condensed matter, mössbauer effect; Nuclear magnetic resonance and relaxation; Physics; Studies of specific magnetic materials; Antiferromagnetism; Curie point; Curie-Weiss law; X-ray diffraction; XRD; EMR; 19F NMR; Niobium fluoride; Line intensity; Monocrystals; Niobium fluorides; Magnetic order; Temperature effects; Nuclear magnetic resonance; Octahedral cluster; Crystal structure
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/j.physb.2005.12.253

In this work, we report updated structural data, obtained by single-crystal X-ray diffraction, on the binary fluoride Nb6F15 as well as measurements of 19F NMR over the temperature range 100-300K, and EMR measurements over the temperature range 4-300K. Nb6F15 is built up from octahedral cluster units sharing all apical fluorine ligands to form linear Nb-Fa-Nb interunit bridges (Fi: inner fluorine located in edge-bridging position, Fa: apical fluorine located in terminal position). The 19F NMR results showed two resonance lines. One line corresponds to the inner fluorine Fi in the (Nb6F12)-3 cluster core. The second 19F NMR line corresponds to the apical Fa. The shift of the NMR signal from Fi depends on the temperature and exhibits a Curie type behavior, while the position of the NMR signal from Fa is temperature independent. EMR measurements show a single Lorentzian line. The temperature dependence of the inverse of the intensity of the EMR line shows a Curie-Weiss behavior and an onset to an antiferromagnetic (AF) order at 5K.