Coexistence of Rutile and Trirutile Phases in a Natural Tapiolite Sample

Kinast, Éder Júlio; Zawislak, Luci Irene; Cunha, J.B.M. da; Antonietti, Volmir; Vasconcellos, M.A.Z.; Santos, Carlos Alberto dos

doi:10.1006/jssc.2001.9395

Cited by 10 publications

(7 citation statements)

References 14 publications

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“…Hyperfine parameters are: ␦ = 1.10(1), 1.06(1) and 1.14(2) mm/s and = 3.02(1), 2.52(1) and 1.85(2) mm/s, respectively. Hyperfine parameters are similar to those presented by Kinast et al (2002). At least three additional doublets of Fe 3+ in octahedral coordination could be fitted, but their hyperfine parameters vary, depending on the specific fit model (more fit models are possible owing to complex overlaps within the range 0 to 1.5 mm/s of the spectra and low Mössbauer response of our samples).…”

Section: Chemical Composition Mössbauer Spectroscopy and X-ray Powdesupporting

confidence: 73%

FERROTAPIOLITE AS A PSEUDOMORPH OF STIBIOTANTALITE FROM THE LASTOVICKY LEPIDOLITE PEGMATITE, CZECH REPUBLIC; AN EXAMPLE OF HYDROTHERMAL ALTERATION AT CONSTANT Ta/(Ta + Nb)

Novák

Černý

Cempírek

et al. 2004

The Canadian Mineralogist

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Dark brown porous ferrotapiolite is a dominant product of alteration in pseudomorphs after primary stibiotantalite from the lepidolite pegmatite at Laštovičky, western Moravia, Czech Republic. Two compositionally distinct varieties of ferrotapiolite were recognized, a volumetrically dominant Fe 3+ -rich phase and a very rare Sb-rich phase. Niobium-rich ferrotapiolite, with up to 17.51 wt.% Nb 2 O 5 (0.61 apfu), is highly heterogeneous, with Ta/(Ta + Nb) of 0. 3 Fe 2+ -2 R 5+ -1 dans la seconde variété pourrait exprimer une solution solide vers le pôle SbTaO 4 , c'est-à-dire la stibiotantalite; toutefois, il est probable que le déplacement en composition est dû à la présence de reliques microscopiques de stibiotantalite primaire dans la ferrotapiolite, cachées sous la surface des échantillons polis. La stibiotantalite est remplacée par la ferrotapiolite le long de fractures distribuées de façon irrégulière selon la réaction hypothétique 2Sb(Ta,Nb)O 4 + Fe(OH) 2 + 2H 2 O = Fe(Ta,Nb) 2 O 6 + 2Sb(OH) 3 . Un tel enrichissement important en fer (stibiotantalite transformée en ferrotapiolite), documenté par la présence d'une abondance de ferrotapiolite secondaire à Laštovičky, est exceptionnelle parmi les produits du remplacement des oxydes primaires de (Nb,Ta) dans les pegmatites granitiques. Les teneurs élevées en Fe 2 O 3 de la ferrotapiolite indiquent des niveaux élevés mais variables de f(O 2 ) au cours de l'altération. Les valeurs de Ta/(Ta + Nb) dans la stibiotantalite primaire et la ferrotapiolite secondaire sont presqu'égales, ce qui fait penser que le Nb et le Ta ont une mobilité très faible. L'absence de fractionnement hydrothermal de Nb par rapport au Ta dans les pegmatites granitiques et la faible mobilité de Ta et Nb, établie ici et dans d'autres travaux, soulignent l'importance des processus magmatiques dans le fractionnement du Ta par rapport au Nb dans la croûte. (Traduit par la Rédaction)Mots-clés: ferrotapiolite, stibiotantalite, altération hydrothermale, fractionnement du Ta par rapport au Nb, pegmatite granitique à lépidolite, Laštovičky, République Tchèque.

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Section: Chemical Composition Mössbauer Spectroscopy and X-ray Powdesupporting

confidence: 73%

FERROTAPIOLITE AS A PSEUDOMORPH OF STIBIOTANTALITE FROM THE LASTOVICKY LEPIDOLITE PEGMATITE, CZECH REPUBLIC; AN EXAMPLE OF HYDROTHERMAL ALTERATION AT CONSTANT Ta/(Ta + Nb)

Novák

Černý

Cempírek

et al. 2004

The Canadian Mineralogist

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“…The Li 0.5 FeF 3 trirutile structure is characterized by edge-sharing among Li + F 6 , Fe 2+ F 6 , and Fe 3+ F 6 octahedra, with a distinct Li + –Fe 2+ –Fe 3+ cationic ordering along the c -axis (Figure b). This creates tunnels that facilitate Li + extraction/insertion from/into the host lattice. ,,, Also, the minor peaks of an impurity FeF 2 phase, seen in the diffraction patterns (Figures S1b and a), are verified as 2.53 wt % by the Rietveld analysis.…”

Section: Resultsmentioning

confidence: 99%

“…This creates tunnels that facilitate Li + extraction/insertion from/into the host lattice. 29,31,35,65 Also, the minor peaks of an impurity FeF 2 phase, seen in the diffraction patterns (Figures S1b and 1a), are verified as 2.53 wt % by the Rietveld analysis.…”

Section: Resultsmentioning

confidence: 99%

Phase Evolution of Trirutile Li_0.5FeF₃ for Lithium-Ion Batteries

et al. 2021

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Extensive studies on the trirutile Li0.5FeF3 phase have been commissioned in the context of Li-Fe-F system for Li-ion batteries. However, progress in electrochemical and structural studies have been greatly encumbered by the low electrochemical reactivity of this material. In order to advance this class of materials, a comprehensive study into the mechanisms of this phase is necessary. Therefore, herein, we report for the first-time overall reaction mechanisms of the ordered trirutile Li0.5FeF3 at elevated temperatures of 90 °C with the aid of a thermally stable ionic liquid electrolyte. The ordered trirutile Li0.5FeF3 is prepared by highenergy ball milling combined with heat treatment followed by electrochemical tests, X-ray diffraction, and X-ray absorption spectroscopic analyses. Our results reveal that a reversible topotactic Li + extraction/insertion from/into the trirutile structure occurs in a twophase reaction with a minor volume change (1.09 % between Li0.5FeF3 and Li0.11FeF3) in the voltage range of 3.2−4.3 V. Extension of the lower cut-off voltage to 2.5 V results in a conversion reaction to LiF and rutile FeF2 during discharging. The subsequent charge triggers the formation of the Li/Fe disordered trirutile structure at 4.3 V without showing the reconversion from LiF and rutile FeF2 to the ordered trirutile Li0.5FeF3 or FeF3.

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“…A crystal fragment was powdered and submitted to two heat treatments: one part was heated in air, while the other was heated in vacuum (P ' 10 À5 Pa). In order to compare with earlier published results (Kinast et al, 2002;, all the samples were heated at 1320 K for 48 h and subsequently slowly cooled at 15 K h À1 . This cooling rate has been retained since it is considered adequate for cation ordering, e.g.…”

Section: Methodsmentioning

confidence: 90%

“…The tantalitecolumbites are sometimes referred to simply as columbite when the Nb content is larger than that of Ta, and tantalite when the Ta concentration is larger than that of Nb. The coexistence of phases in a natural tapiolite sample has been investigated by different techniques including Mö ssbauer spectroscopy, X-ray diffraction and microprobe analysis (dos Santos et al, 2001;Kinast et al, 2002;Tarantino et al, 2003). These minerals are economically important since they are the major source of tantalum.…”

Section: Introductionmentioning

confidence: 99%

A new approach for the determination of multiple cation locations and ordering, using the example of natural and heat-treated columbites

Kinast¹,

Isnard²,

Cunha³

et al. 2011

J Appl Cryst

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A new approach is proposed to determine unambiguously the location of four cations within the crystal structure of a natural AB 2 O 6 columbite-type compound and derivatives, when submitted to order-disorder transitions caused by heat treatments. This method is based on the successive use of electron microprobe analysis to determine the cation concentration, Mö ssbauer spectroscopy to identify the Fe occupation, and a crystal structure determination of the samples combining Rietveld refinements of both neutron and X-ray diffraction. This approach is tested successfully to investigate (Fe, Mn, Nb, Ta) natural minerals as well as oxides obtained by heat treatment of the initial AB 2 O 6 columbite-type compound.

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Coexistence of Rutile and Trirutile Phases in a Natural Tapiolite Sample

Cited by 10 publications

References 14 publications

FERROTAPIOLITE AS A PSEUDOMORPH OF STIBIOTANTALITE FROM THE LASTOVICKY LEPIDOLITE PEGMATITE, CZECH REPUBLIC; AN EXAMPLE OF HYDROTHERMAL ALTERATION AT CONSTANT Ta/(Ta + Nb)

FERROTAPIOLITE AS A PSEUDOMORPH OF STIBIOTANTALITE FROM THE LASTOVICKY LEPIDOLITE PEGMATITE, CZECH REPUBLIC; AN EXAMPLE OF HYDROTHERMAL ALTERATION AT CONSTANT Ta/(Ta + Nb)

Phase Evolution of Trirutile Li_0.5FeF₃ for Lithium-Ion Batteries

A new approach for the determination of multiple cation locations and ordering, using the example of natural and heat-treated columbites

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Coexistence of Rutile and Trirutile Phases in a Natural Tapiolite Sample

Cited by 10 publications

References 14 publications

FERROTAPIOLITE AS A PSEUDOMORPH OF STIBIOTANTALITE FROM THE LASTOVICKY LEPIDOLITE PEGMATITE, CZECH REPUBLIC; AN EXAMPLE OF HYDROTHERMAL ALTERATION AT CONSTANT Ta/(Ta + Nb)

FERROTAPIOLITE AS A PSEUDOMORPH OF STIBIOTANTALITE FROM THE LASTOVICKY LEPIDOLITE PEGMATITE, CZECH REPUBLIC; AN EXAMPLE OF HYDROTHERMAL ALTERATION AT CONSTANT Ta/(Ta + Nb)

Phase Evolution of Trirutile Li0.5FeF3 for Lithium-Ion Batteries

A new approach for the determination of multiple cation locations and ordering, using the example of natural and heat-treated columbites

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Phase Evolution of Trirutile Li_0.5FeF₃ for Lithium-Ion Batteries