7784-18-1Relevant articles and documents
Electron-beam induced crystallization transition in self-developing amorphous AIF3 resists
Chen,Boothroyd,Humphreys
, p. 170 - 172 (1996)
Transmission electron microscopy is used to investigate electron-induced crystallization of thermally evaporated amorphous AlF3(α-AlF3). It is shown that this material undergoes a very complicated crystallization process with three crystalline substances (Al, AlF3, and Al2O3) formed as the dose increases. The sequence of the crystallization is highly sensitive to the presence of water, which inhibits radiolytic dissociation of α-AlF3 into Al and fluorine, reduces the dose required for the crystallization of α-AlF3, and causes the transformation of AlF3 into Al2O3.
Characterization of four phase transitions in Pb5Al3F19, including a new transition at 670 K, by impedance and NMR spectroscopy
El Omari,Reau,Senegas,Ravez,Abrahams,Nadiri,Yacoubi
, p. 2896 - 2902 (1998)
X-ray diffraction, thermal, optical, and dielectric studies of Pb5Al3F19 undertaken previously between 100 and 400 K showed this material undergoes three phase transitions. The four known phases are ferroelectric phase V, with a transition to antiferroelectric phase IV at 270 K on heating, 140 K on cooling. The transition from phase IV to ferroelastic phase III is at 320 K on heating, 305 K on cooling; that from phase III to paraelastic phase II is at 360 K without thermal hysteresis. Impedance and NMR spectroscopy in the complementary temperature ranges 279-743 and 125-430 K characterized the influence of these phases on the ionic conductivity and F- ion diffusion properties in this material.
Reactivity of fluorinated γ-alumina and β-aluminium(III) fluoride surfaces towards hydrogen halides and tert-butyl chloride
Barclay, Christopher H.,Bozorgzadeh, Hamid,Kemnitz, Erhard,Nickkho-Amiry, Mahmood,Ross, Debbie E.M.,Skapin, Tomaz,Thomson, James,Webb, Geoffrey,Winfield, John M.
, p. 40 - 47 (2002)
The Lewis acids β-aluminium(III) fluoride and γ-alumina, fluorinated at room temperature with sulfur, tetrafluoride, both interact with hydrogen fluoride and chloride, as demonstrated by radiotracer measurements using [18F] and [36Cl
Zeolite catalysts for Halon conversion
Howe,Lee,Thomson,Kennedy,Yang,Dlugogorski
, p. 63 - 72 (2002)
The chemical states of Al and Ni in NiZSM-5 catalyst used for the pyrolysis and hydrodehalogenation with methane of Halon 1301 (CF3Br) were characterized using Al and Ni K-edge XANES and EXAFS experiments. Reaction products were CF4
Vibrational analysis study of aluminum trifluoride phases
Gross, Udo,Ruediger, Stephan,Kemnitz, Erhard,Brzezinka, Klaus-Werner,Mukhopadhyay, Sanghamitra,Bailey, Christine,Wander, Adrian,Harrison, Nicholas
, p. 5813 - 5819 (2007)
The vibrational modes of three solid AlF3 phases (α, β, and amorphous high surface area AlF3) are investigated. Calculations have been performed using hybrid exchange correlation functionals to determine the equilibrium geometries an
The effects of AlF3 coating on the performance of Li[Li 0.2 Mn0.54 Ni0.13 Co0.13]O 2 positive electrode material for lithium-ion battery
Zheng,Zhang,Wu,Dong,Zhu,Yang
, p. A775-A782 (2008)
Al F3 -coated Li [Li0.2 Mn0.54 Ni0.13 Co0.13] O2 materials have been synthesized as positive electrode materials for lithium-ion batteries. The pristine and Al F3 -coated Li [Li0.2 Mn0.54 Ni0.13 Co0.13] O2 materials were characterized by X-ray diffraction
AlF3-coating to improve high voltage cycling performance of Li[Ni1/3Co1/3Mn1/3]O2 cathode materials for lithium secondary batteries
Sun,Cho,Lee,Yoon,Amine
, p. A168-A172 (2007)
Li [Ni13 Co13 Mn13] O2 powders were modified by coating their surface with amorphous AlF3 as a new coating material. The AlF3 -coated Li [Ni13 Co13 Mn13] O2 electrode showed improved cycle performance and rate capability under a high cutoff voltage range of 4.5 and 4.6 V. AC impedance results showed that the AlF3 -coated Li [Ni13 Co13 Mn13] O2 has stable charge transfer resistance (Rct) regardless of the cycle number. Electron diffraction analysis also showed that no structural transition of the primary particles was observed for the AlF3 -coated electrode. Electrochemical impedance spectroscopy and electron microscopy indicate that AlF3 coating plays an important role of stabilizing the interface between cathode and electrolyte.
Investigation of the systems KAlF4-M3AlF6 (M=Rb, Cs)
Chen,Zhang
, p. 117 - 120 (2000)
Phase relations in the systems KAlF4-Rb3AlF6 and KAlF4-Cs3AlF6 were investigated by DTA and XRD methods for the purpose of finding a low melting, non-corrosive aluminum flux. In each system, congruent compounds Rb3AlF6·2KAlF4 and 2Cs3AlF6·3KAlF4 were observed, respectively. Eutectics located at 46 mol% Rb3AlF6 and 511°C, 25 mol% Rb3AlF6 and 512°C for the former system, and 48 mol% Cs3AlF6 and 550°C, 25 mol% Cs3AlF6 and 480°C in the latter were confirmed. The phase α-2Cs3AlF6·3KAlF4 was XRD indexed as having an orthorhombic cell a=10.401±0.003, b=10.078±0.006, c=8.792±0.006 A?. (C) 2000 Elsevier Science B.V.
Tossing and turning: Guests in the flexible frameworks of metal(III) dicarboxylates
Vougo-Zanda, Marie,Huang, Jin,Anokhina, Ekaterina,Wang, Xiqu,Jacobson, Allan J.
, p. 11535 - 11542 (2008)
Single crystals of Ga(OH)(C8H4O4) ·0.74C8H6O4 (2) and Ga(OH,F)(C 8H4O4)·0.74C8H 6O4 (3) were obtained under hydrothermal conditions. The structures of 2 and 3 have the same topological framework as the previously reported aluminum 1,4-benzenedicarboxylate (BDC), Al(OH)(C8H 4O4)·0.7C8H6O4 (1). The frameworks are built by interconnecting M-OH-M chains (M = Al, Ga) with BDC anions to form large diamond-shaped one-dimensional channels filled with additional H2BDC guest molecules occupying disordered positions in the channels. Upon removal of H2BDC, other guest molecules such as H2O and pyridine can be inserted. In this work, we present a study of the intercalation of aromatic guests (BDC and pyridine) into frameworks of 1-3 by liquid and vapor diffusion into the empty channels of 1 and by single-crystal-to-single-crystal solvothermal guest exchange for 2 and 3. In the case of Al(OH)BDC and Ga(OH,F)BDC, two interconvertible, guest-concentration- dependent phases with different orientations of the pyridine guests have been observed, while only one pyridine orientation is found in Ga(OH)BDC.
Structural insights into aluminum chlorofluoride (ACF)
Krahl, Thoralf,Stoesser, Reinhard,Kemnitz, Erhard,Scholz, Gudrun,Feist, Michael,Silly, Gilles,Buzare, Jean-Yves
, p. 6474 - 6483 (2003)
The structure of the very strong solid Lewis acid aluminum chlorofluoride (ACF, AlClxF3-x = 0.05-0.3) was studied by IR, ESR, Cl K XANES, 19F MAS NMR, and 27Al SATRAS NMR spectroscopic methods and compared with amorphous aluminum fluoride conventionally prepared by dehydration of α-AlF3·3H2O. The thermal behavior of both compounds was investigated by DTA and XRD. In comparison to ACF, amorphous AlF3 prepared in a conventional way is not catalytically active for the isomerization reaction of 1,2-dibromohexafluoropropane, which requires a very strong Lewis acid. Both compounds are mainly built up of corner-sharing AlF6 octahedra forming a random network. The degree of disorder in ACF is higher than in amorphous AlF3. Terminal fluorine atoms were detected in ACF by 19F NMR. The chlorine in ACF does not exist as a separate, crystalline AlCl3 phase. Additionally, chlorine-containing radicals, remaining from the synthesis, are trapped in cavities of ACF. These radicals are stable at room temperature but do not take part in the catalytic reaction.
Pitton, O.,Jorgensen, C. K.,Berthou, H.
, p. 357 - 361 (1976)
Hypothetical AlF3 crystal structures
Le Bail, Armel,Calvayrac, Florent
, p. 3159 - 3166 (2006)
Applying a structure prediction computer programme (GRINSP=Geometrically Restrained INorganic Structure Prediction), the occurrence of 6-connected 3D networks was investigated, through AlF6 octahedra exclusive corner sharing. The five known AlF3 varieties were reproduced (α-, β-, η-, κ- and τ-AlF3) and seven hypothetical models were predicted. Among these still to be synthesized AlF3 phases, one can recognize two known structure types (TlCa2Ta5O15, Ba4CoTa10O30) and some easy to imagine intergrowths; however, a few others are completely unexpected, though simple. A comparison of the ab initio total energies of all the structures is provided, leading to the conclusion that the virtual models could well be viable.
Infrared Surface Characterization of AlF3
Morterra, C.,Cerrato, G.,Cuzzato, P.,Masiero, A.,Padovan, M.
, p. 2239 - 2250 (1992)
Three specimens of crystalline AlF3, coming from different preparation routes, have been examined: no major differences were found in the spectral region of the (ν3) fundamental mode, whereas the preparation process was observed to introduce appreciable differences in the background spectra that were ascribed to different bulk and surface impurities.Oxidic islands exist both in the bulk and at the surface of all preparations and when AlF3 is derived from non-oxygen-containing precursors.In the latter case, species containing NHx moieties exist, both in the bulk and at the surface.The surface hydrated layer of AlF3 is made up of an extensive 'regular' component (i.e. a large amount of undissociated water molecules, coordinated to unsaturated surface AlVI cations), and not an 'anomalous' component (i.e. some OH groups that are eliminated upon vacuum activation at relatively low temperatures).The adsorption of pyridine on samples activated by vacuum treatment at temperatures in the range 300-673 K indicates that on all specimens there are variable amounts of 'irregular' surface cations , some of which are strong enough as Lewis-acidic centres to adsorb CO at ambient temperature.Coordinatively unsaturated surface Al ions with the 'regular' octahedral coordination are very weakly acidic, as revealed by the end-on adsorption of CO2 at 300 K and by CO uptake at ca. 78 K.
SMARTER crystallography of the fluorinated inorganic-organic compound Zn3Al2F12·[HAmTAZ]6
Martineau, Charlotte,Cadiau, Amandine,Bouchevreau, Boris,Senker, Juergen,Taulelle, Francis,Adil, Karim
, p. 6232 - 6241 (2012/06/15)
We present in this paper the structure resolution of a fluorinated inorganic-organic compound - Zn3Al2F12· [HAmTAZ]6 - by SMARTER crystallography, i.e. by combining powder X-ray diffraction crystallography, NMR crystallography and chemical modelling of crystal (structure optimization and NMR parameter calculations). Such an approach is of particular interest for this class of fluorinated inorganic-organic compound materials since all the atoms have NMR accessible isotopes (1H, 13C, 15N, 19F, 27Al, 67Zn). In Zn3Al2F 12·[HAmTAZ]6, 27Al and high-field 19F and 67Zn NMR give access to the inorganic framework while 1H, 13C and 15N NMR yield insights into the organic linkers. From these NMR experiments, parts of the integrant unit are determined and used as input data for the search of a structural model from the powder diffraction data. The optimization of the atomic positions and the calculations of NMR parameters (27Al and 67Zn quadrupolar parameters and 19F, 1H, 13C and 15N isotropic chemical shifts) are then performed using a density functional theory (DFT) based code. The good agreement between experimental and DFT-calculated NMR parameters validates the proposed optimized structure. The example of Zn 3Al2F12·[HAmTAZ]6 shows that structural models can be obtained in fluorinated hybrids by SMARTER crystallography on a polycrystalline powder with an accuracy similar to those obtained from single-crystal X-ray diffraction data.
Highly selective metal fluoride catalysts for the dehydrohalogenation of 3-chloro-1,1,1,3-tetrafluorobutane
Teinz, Katharina,Wuttke, Stefan,Boerno, Fabian,Eicher, Johannes,Kemnitz, Erhard
, p. 175 - 182 (2011/10/18)
For the first time, dehydrochlorination and dehydrofluorination reactions are studied on the same substrate, 3-chloro-1,1,1,3-tetrafluorobutane, employing nanoscopic metal fluorides AlF3, MgF2, CaF2, SrF2, and BaF2 as catalysts that are prepared according the fluorolytic sol-gel synthesis. AlF3 is exclusively selective toward dehydrofluorination, whereas BaF2 is 100% selective toward dehydrochlorination. The acid-base character of the catalysts is investigated and, as a result, mechanistic proposals for the dehydrofluorination and the dehydrochlorination are given. Thus, at high conversion level, selective catalysts for both dehydrofluorination and dehydrochlorination on the same substrate have been developed.