13709-38-1Relevant articles and documents
Hydrothermal syntheses and crystal structure of NH4Ln3F10 (Ln = Dy, Ho, Y, Er, Tm)
Kang,Wang,You,Lin
, p. 358 - 362 (2001)
Ammonium rare earth fluorides NH4Ln3F10 (Ln = Dy, Ho, Y, Er, Tm) were synthesized by a hydrothermal method. Two polymorphs, of the hexagonal β-KYb3F10 and the cubic γ-KYb3F10 structure types, were formed under hydrothermal conditions for most of the rare earth fluorides except NH4Dy3F10, for which only the cubic γ-phase was obtained. The crystal structures of MLn3F10 (M = alkaline metal, NH4+ and Ln = rare earth) show a strong correlation to the ratio of ionic radii (RM/RLn), which has been expressed in a structure phase diagram of the ionic radii of univalent and rare earth cations.
Stabilization of a new superconducting phase by low temperature fluorination of La2CuO4
Chevalier, B.,Tressaud, A.,Lepine, B.,Amine, K.,Dance, J. M.,et al.
, (1990)
When La2CuO4 is treated with pure F2 gas at 200°C, the X-ray diffraction pattern of the resulting product is characteristic of a new single phase derived from the K2NiF4-type structure. An enhancement of the orthorhombic distortion relative to the starting oxide is observed with: a=5.342 angstrom; b=5.436 angstrom and c=13.192 angstrom. Both weight uptake and increase of the c unit cell constant could be consistent with an incorporation of fluorine atoms in the lattice. This new compound is superconducting at Tc=40 K with Hc1' 700 Oe and exhibits a strong diamagnetic susceptibility (Xg= -6.13 × 10-3 emu/g) at 6 K under an applied field of 1 Oe.
A thermal study of several lanthanide triflates
Yanagihara, Naohisa,Nakamura, Shin,Nakayama, Masayoshi
, p. 3625 - 3631 (1998)
Five lanthanide triflates, Ln(TfO)3·nH2O, where TfO-=CF3SO3-, Ln=La3, Nd3, Sm3, Gd3 and Yb3, and n=9 and 13, have been prepared and the thermal decomposition processes of these triflates up to 600°C were characterized by means of TG, DTA, XRD. The thermal studies have shown almost all the lanthanide triflates prepared in this study to exist as a stable nonahydrate. During the stepwise dehydration processes, it was found that mono-, di-, tri-, penta-, and heptahydrates were formed. Decompositions were found to be exothermic, and calcinations of these triflates at 600°C resulted in the formation of the corresponding LnF3. Crystal systems of the trifluorides thus obtained were hexagonal for La, Nd and Sm trifluorides, whereas those of Gd and Yb were found to be orthorhombic. The volatile decomposition products at 600°C were identified by MS, and it was revealed that the over all reaction scheme for the thermal decomposition proceeds as follows: Ln(OTf)3→LnF3+3SO2+CO2+CF 3OCF3.
Isolation of niobium, tantalum, and titanium complex fluoride salts with alkali metal cations
Nikolaev,Kirichenko,Rys'kina
, p. 1070 - 1075 (2009)
Fluoride and oxofluoride salts of niobium, tantalum, and titanium were isolated. They precipitated from aqueous solutions and upon washing of organic extracts with aqueous solutions of ammonium, potassium, and sodium salts. The compositions of the isolate
Solvent-assisted selective synthesis of NaLaF4 and LaF 3 fluorescent nanocrystals via a facile solvothermal approach
Wang, Zhe,Liu, Chenghui,Wang, Yucong,Li, Zhengping
, p. 1964 - 1968 (2011)
A facile solvothermal approach was developed to selectively synthesize water-soluble NaLaF4 or LaF3 nanocrystals (NCs) by tuning the solvent components. In ethonal/H2O media, high-quality LaF 3 NCs were prepared by using NaF and LaCl3 as the precursors. More interestingly, thermodynamically non-preferred NaLaF 4 nanorods could be obtained when ethylenediamide (EN) was introduced to the ethonal/H2O solvent. All of the products were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), and the crucial effects of EN on morphology and structure of the NCs were studied. Furthermore, by doping different lanthanide ions, these LaF3 and NaLaF4 NCs could emit intense upconversion (UC) or downconversion (DC) fluorescence, which showed potential applications in color displays, light-emitting diodes, optical storage and optoelectronics.
Electrochemical fluorination of La2CuO4: A mild "chimie douce" route to superconducting oxyfluoride materials
Delville,Barbut,Wattiaux,Bassat,Menetrier,Labrugere,Grenier,Etourneau
, p. 7962 - 7969 (2009)
The fluorination of La2CuO4 was achieved for the first time under normal conditions of pressure and temperature (1 MPa and 298 K) via electrochemical insertion in organic fluorinated electrolytes and led to lanthanum oxyfluorides of general formula La2CuO4F x. Analyses showed that, underneath a very thin layer of LaF 3 (a few atomic layers), fluorine is effectively inserted in the material's structure. The fluorination strongly modifies the lanthanum environment, whereas very little modification is observed on copper, suggesting an insertion in the La2O2 blocks of the structure. In all cases, fluorine insertion breaks the translation symmetry and introduces a long-distance disorder, as shown by electron spin resonance. These results highlight the efficiency of electrochemistry as a new "chimie douce" type fluorination technique for solid-state materials. Performed at room temperature, it additionally does not require any specific experimental care. The choice of the electrolytic medium is crucial with regard to the fluorine insertion rate as well as the material deterioration. Successful application of this technique to the well-known La2CuO4 material provides a basis for further syntheses from other oxides.
Synthesis of lanthanum fluoride nanocrystals and modification of their surface
Safronikhin,Ehrlich,Lisichkin
, p. 277 - 281 (2011)
The LaF3 nanoparticles were synthesized in the presence of citric acid and glycine. The products were characterized by X-ray phase analysis, transmission electron microscopy, dynamic light scattering, and infrared spectroscopy. In the presence of organic acids the synthesis was shown to result in a decrease in size of the formed particles. The IR spectroscopic studies revealed that citric acid and glycine acted as modifiers of the surface of LaF3 particles forming a chemical bond with the surface ions La3+. A suggestion was advanced on the structure of the grafted surface layer. The features of the colloidal behavior of the systems were investigated.
PHENOMENOLOGICAL COMPARISON OF SOME HEAVY METAL FLUORIDE GLASSES IN WATER ENVIRONMENTS.
Robinson,Drexhage
, p. 1101 - 1112 (1983)
The details of corrosive attack by water on several heavy metal fluoride glasses are given. The glasses studied contained either ZrF//4 or HfF//4 as primary constituents, or, were composed of the fluorides of zinc, thorium, barium and either yttrium or ytterbium. Polished specimens were subjected either to room temperature (RT) liquid water or to 100% relative humidity at room temperature. The degree of surface corrosion was correlated with the preparatory and compositional effects. Thermogravimetric analysis (TGA) was utilized to determine the extent of corrosion as a function of temperature and as a function of time at constant temperature in an atmosphere of RT helium saturated with water.
Infrared spectra and quantum chemical calculations of the bridge-bonded HC(F)LnF2 (Ln = La-Lu) complexes
Gong, Yu,Wang, Xuefeng,Andrews, Lester,Chen, Mingyang,Dixon, David A.
, p. 4443 - 4452 (2011)
Lanthanide metal atoms, produced by laser ablation, were condensed with CHF3 (CDF3) in excess argon or neon at 4 K, and new infrared absorptions are assigned to the oxidative addition product fluoromethylene lanthanide difluoride complex on the basis of deuterium substitution and density functional theory frequency calculations. Two dominant bands in the 500 cm-1 region are identified as metal-fluorine stretching modes. A band in the mid-600 cm-1 region is diagnostic for the unusual fluorine bridge bond C-(F)-Ln. Our calculations show that most of the bridged HC(F)LnF2 structures are 3-6 kcal/mol lower in energy than the open CHF-LnF2 structures, which is in contrast to the open structures observed for the corresponding CH2-LnF2 methylene lanthanide difluorides. Argon-to-neon matrix shifts are 15-16 cm -1 to the blue for stretching of the almost purely ionic Ln-F bonds, as expected, but 10 cm-1 to the red for the bridge C-(F)-Ln stretching mode, which arises because Ar binds more strongly to the electropositive Ln center, decreasing the bridge bonding, and thus allowing a higher C-F stretching frequency.
Phase transition and compressibility of LaF3 under pressures up to 40 GPa
Dyuzheva,Lityagina,Demishev,Bendeliani
, p. 59 - 61 (2002)
The compressibility of LaF3 (tysonite) has been studied up to 40 GPa using X-ray diffraction in a diamond anvil cell. A phase transition from tysonite to an orthorhombic phase (Cmma, No. 67) was observed at a pressure of 19 GPa at room temperature. The volume discontinuity was ΔV/V0 = -0.077 at the transition point. The cell parameters of the high-pressure phase are a=8.221(6) A?, b=8.589(9) A?, c=5.231(6) A?, Z=8 at p=16 GPa, which is accepted conventionally as equilibrium. The bulk moduli and pressure derivatives calculated by fitting V(p) data to the Birch-Murnagan equation of state are presented for both phases.
