Low temperature synthesis of LnOF rare-earth oxyfluorides through reaction of the oxides with PTFE

Journal Article · Thu Mar 15 04:00:00 EDT 2012 · Materials Research Bulletin

DOI:https://doi.org/10.1016/J.MATERRESBULL.2011.12.014· OSTI ID:22212459

Hirai, D.; Cava, R. J. ^[1]

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1. Department of Chemistry, Princeton University, Princeton, NJ 08544 (United States)

Highlights: Black-Right-Pointing-Pointer Low temperature synthesis of LnOF rare-earth oxyfluorides from Ln{sub 2}O{sub 3} and PTFE (CF{sub 2}). Black-Right-Pointing-Pointer Rhombohedral LnOF is the major phase and forms as nanocrystals, 29-103 nm. Black-Right-Pointing-Pointer Expected lanthanide contraction observed in lattice parameters and bond lengths. Black-Right-Pointing-Pointer TbOF orders antiferromagnetically at 10 K and has a metamagnetic transition at 1.8 T. Black-Right-Pointing-Pointer GdOF orders antiferromagnetically at 5 K, other LnOF are paramagnetic. -- Abstract: A low temperature solid-state synthesis route, employing polytetrafluoroethylene (PTFE) and the rare-earth oxides, for the formation of the LnOF rare-earth oxyfluorides (Ln = Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er), is reported. With the exception of LaOF, which forms in a tetragonal variant, rhomobohedral LnOF is found to be the major product of the reaction. In the case of PrOF, a transition from the rhombohedral to the cubic fluorite phase is observed on heating in air to 500 Degree-Sign C. X-ray diffraction shows the expected lanthanide contraction in the lattice parameters and bond lengths. Magnetic susceptibility measurements show antiferromagnetic-like ordering in TbOF, T{sub m} = 10 K, with a metamagnetic transition at a field {mu}{sub 0}H{sub t} = 1.8 T at 2 K. An antiferromagnetic transition, T{sub N} = 4 K, is observed in GdOF. Paramagnetic behavior is observed above 2 K in PrOF, NdOF, DyOF, HoOF and ErOF. The magnetic susceptibility of EuOF is characteristic of Van Vleck paramagnetism.

• OSTI ID: 22212459
• Journal Information: Materials Research Bulletin, Journal Name: Materials Research Bulletin Journal Issue: 3 Vol. 47; ISSN MRBUAC; ISSN 0025-5408
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ANTIFERROMAGNETISM
BOND LENGTHS
FLUORITE
LATTICE PARAMETERS
MAGNETIC SUSCEPTIBILITY
NANOSTRUCTURES
OXIDES
OXYFLUORIDES
PARAMAGNETISM
RARE EARTHS
SYNTHESIS
TEFLON
TRIGONAL LATTICES
X-RAY DIFFRACTION