Phase analyses of lanthanide oxide fluorides

Shinn, Dennis B.,Eick, Harry A.

, p. 232 - 235 (1969)

Approximate composition limits and lattice parameters of the rhombohedral and tetragonal phases observed in the system LnO1-xF1+2x (Ln = Nd, Gd, Er) are reported. Variation of the c/a ratio of the tetragonal phase with atomic number is noted and discussed. The rhombohedral to cubic transition temperatures of LnO1-xF1+2x (Ln = La, Nd, Sm, Eu, Gd, Tb, Dy, Y, Ho, and Er) determined from differential thermal analysis are reported and the transition is discussed. Thermal expansion data are reported for NdOF and its mode of thermal decomposition is indicated.

Synthesis and characterization of Ba1-xNdxF2+x (0.00 ≤ x ≤ 1.00)

Grover,Achary,Patwe,Tyagi

, p. 1101 - 1111 (2003)

A series of mixed fluorides with general composition Ba1-xNdxF2+x (0.00 ≤ x ≤ 1.00) was prepared by vacuum heat treatment of the mixture of starting fluorides, and analyzed by powder XRD. From the XRD analysis, the low temperature phase equilibria in BaF2-NdF3 system is elucidated. The initial compositions in this series, that is, up to the nominal composition Ba0.65Nd0.35F2.35 (x ≤ 0.35) exist as cubic fluorite-type solid solution. Beyond the solid solution limit, that is, x ≥ 0.35, a rhombohedral fluorite related ordered phase is observed. Further, NdF3-rich compositions (x ≥ 0.50) exist as a mixture of rhombohedral ordered phase and NdF3 (tysonite)-type phase. About 10 mol% of BaF2 could be retained in the NdF3 lattice, forming a tysonite-type solid solution, under the short annealed and slow cooled conditions.

Vicentini, G.,Zinner, L. B.,Chaparro, R. P.,Dunstan, P. O.

, p. 341 - 345 (1991)

Heterometallic Ln/Hg compounds with fluorinated thiolate ligands

Banerjee, Santanu,Emge, Thomas J.,Brennan, John G.

, p. 6307 - 6312 (2004)

The early lanthanide benzenefluorothiolates (Ln(SC6F 5)3; Ln = La, Ce, Pr, Nd, Sm, Gd) react with Hg(SC 6F5)2 in DME to form ionic heterometallic compounds with Ln cations and Hg anions. X-ray diffraction analyses of all compounds reveal an isostructural series with the general formula [(DME) 3Ln(SC6F5)2]2[Hg 2(SC6F5)6]. In the structures, a fluorothiolate ligand has been extracted from the Ln coordination sphere that is saturated with three neutral DME donor ligands and a dative interaction between one ortho fluorine and the Ln. Distances between Ln and F do not vary simply with Ln ionic radius. There are two Ln cations with charge balanced by a Hg 2(SC6F5)6 dianion composed of two distinctly nonideal Hg(II) tetrahedra, all connected through a series of π-π interactions that link cations with anions in a one-dimensional array and anions to anions in a more complex 2D network.

Spectroscopic characterization of Ho3+ ion-doped fluoride glass

Florez,Oliveira,Flórez,Gómez,Nunes

, p. 238 - 242 (2006)

Among the new optical materials available, fluoride glass, which has an extended transmission window, is emerging as an important material for use in optical fibers, lasers, sensors, etc. Here, we analyze the spectroscopic properties of Ho3+ ions in a fluoroindate glass based on absorption measurements. Ho3+-doped fluoroindate glass with the composition (40 - x)InF3-20SrF2-20ZnF2-16BaF2-2GdF3-2NaF-xHoF3, x = 1.0, 2.0, 2.5, 3.0, 4.0, 5.0, 6.0, 8.0 and 9.0 mol%, was prepared under an argon atmosphere. Absorption spectra in the range 300-2200 nm were then obtained. The experimental oscillator strength fExp. was calculated from the areas under absorption bands. Using Judd-Ofelt theory and least-squares fitting, the phenomenological intensity parameter Ωλ (λ = 2, 4, 6) and the theoretical oscillator strength fCal. were calculated. To evaluate potential applications and to analyze the properties of Ho3+ ions in these host glasses, the following spectroscopy parameters were calculated: the transition probability between multiplets AJJ′, the branching ratio βJJ′, the radiative lifetime τR, the peak cross-section for stimulated emission σp, and the emitting-level multiphonon rate WNR for each band. The results were compared with those reported in the literature for similar glasses of the same concentration.

Synthesis and characterization of LnF(HF)(BF4)2 (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, and Dy), and crystal structures of LnF(HF)(BF4)2 (Ln = Pr, Nd) and La(BF4) 3

Mazej, Zoran,Goreshnik, Evgeny,Hironaka, Kohei,Katayama, Yasushi,Hagiwara, Rika

, p. 2309 - 2315 (2009)

Rare earth trifluorides (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, and Dy) react with boron trifluoride in anhydrous hydrogen fluoride (aHF) at room temperature. Products were found to be only sparingly soluble in aHF where the solubility decreases from lantha

Hydrofluoride synthesis of fluorides of some rare-earth elements

Kalinnikov,Makarov,Tikhomirova,Elizarova,Kuznetsov

, p. 1760 - 1764 (2002)

Thermal gravimetric, X-ray phase, IR spectroscopic, and chemical analyses were applied to study the reaction of yttrium and neodymium oxides with NH 4HF2.

Phase relation studies in Pb1-xM′xF 2+x systems (0.0≤x≤1.0; M′=Nd3+, Eu 3+ and Er3+)

Tyagi,Patwe,Achary,Mallia

, p. 1746 - 1757 (2004)

In this communication we report the synthesis and characterization of a series of compounds with the general composition Pb1-xM′ xF2+x, (0.0≤x≤1.0; M′=Nd3+, Eu 3+ and Er3+) to elucidate the detailed phase relations between PbF2 and M′F3. These three rare-earth fluorides were selected so as to delineate the effect of ionic size on the phase relations. In all the three systems, fluorite-type solid solutions are formed at the PbF2 rich end. The solid solubility limits of NdF 3, EuF3 and ErF3 in the PbF2 lattice, as observed from this study, are 30, 25 and 15mol%, respectively. In PbF2-NdF3 system, beyond the fluorite-type solid solutions, NdF3 phase is observed. However, in both PbF 2-EuF3 and PbF2-ErF3 systems, certain fluorite related ordered phases, namely, a rhombohedral phase with about 40mol% of EuF3 or ErF3 in PbF2, and a tetragonal phase with 45-50mol% of ErF3 in PbF2, are observed. In all the three systems, no solubility of the PbF2 in the hexagonal or orthorhombic rare-earth fluoride lattice is observed. This is the first report on phase relation in these three systems under short annealed and slow cooled condition.

X-ray magnetic circular dichroism (XMCD) study of a methoxide-bridged DyIII-CrIII cluster obtained by fluoride abstraction from cis-[CrIIIF2(phen)2]+

Dreiser, Jan,Pedersen, Kasper S.,Birk, Torben,Schau-Magnussen, Magnus,Piamonteze, Cinthia,Rusponi, Stefano,Weyhermueller, Thomas,Brune, Harald,Nolting, Frithjof,Bendix, Jesper

, p. 7842 - 7847 (2012/09/22)

An isostructural series of dinuclear chromium(III)-lanthanide(III) clusters is formed by fluoride abstraction of cis-[CrF2(phen) 2]+ by Ln3+ resulting in LnF3 and methoxide-bridged Cr-Ln clusters (Ln = Nd (1), Tb (2), Dy (3)) of formula [CrIII(phen)2(μ-MeO)2Ln(NO3) 4]?xMeOH (x = 2-2.73). In contrast to fluoride, methoxide bridges in a nonlinear fashion, which facilitates chelation. For 3, X-ray magnetic circular dichroism (XMCD) provides element-specific magnetization curves that are compared to cluster magnetization and susceptibility data acquired by SQUID magnetometry. The combination of XMCD and SQUID is able to resolve very small magnetic coupling values and reveals a weak Cr III-DyIII coupling of j = -0.04(3) cm-1. The DyIII ion has a ground-state Kramers doublet of mJ = ±13/2, and the first excited doublet is found to be mJ = ±11/2 at an energy of δ = 57(21) cm-1. The Cr III ion exhibits a uniaxial anisotropy of DCr = -1.7(1.0) cm-1. Further, we observe that a weak anisotropic coupling of dipolar origin is sufficient to model the data, suggesting that methoxide bridges do not play a significant role in the magnetic coupling for the present systems.

The versatility of solid-state metathesis reactions: From rare earth fluorides to carboiimides

Unverfehrt, Leonid,Glaser, Jochen,Stroebele, Markus,Tragl, Sonja,Gibson, Katharina,Meyer, H.-Juergen

, p. 479 - 483 (2009/06/17)

The new carbodiimide compounds LaF(CN2) and LiPr 2F3(CN2)2 were obtained as crystalline powders by solid-state metathesis reactions from 1:1 molar ratios of REF3 (RE = rare earth) and Lisu