Mössbauer Assessment of Cation Disorder in Columbite–Tantalite Minerals

Augsburger, M. S.; Pedregosa, J. C.; Sosa, Graciela; Mercader, R. C.

doi:10.1006/jssc.1998.8090

Cited by 7 publications

(6 citation statements)

References 5 publications

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“…The problem is how to assess the degree of cation order. For columbite samples, there is Ercit's formula (11) based on the a and c unit cell parameters and a MoK ssbauer-based parameter recently proposed by Augsburger et al (13),…”

Section: Resultsmentioning

confidence: 99%

“…It is obvious that MS probes exclusively Fe cation ordering. However, assuming equal f-factors for both sites of the trirutile structure (supported by the MS measurements at 80 K) and the same probability for site occupancy of both Fe and Mn, Augsburger et al (13) were able to propose the cation order degree parameters given above for columbite samples, which can also be used for tapiolite ones.…”

Section: Discussionmentioning

confidence: 96%

“…Therefore, according to these authors, a quick and simple means of determining the degree of order in this kind of material is not yet available. Recently it has been demonstrated that MoK ssbauer spectroscopy (MS) is a very e$cient tool to investigate order}disorder phenomena in the orthorhombic series (9,12,13). As long as hyper"ne interactions are very sensitive to change of the near-nearest environment, MS enables us to easily di!erentiate Fe on the A site from Fe on the B site.…”

Section: Introductionmentioning

confidence: 99%

“…The cation order parameter proposed by Augsburger et al (13) for columbite samples will be used here to quantify the cation order percentage.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Coexistence of Rutile and Trirutile Phases in a Natural Tapiolite Sample

Kinast

Zawislak

Cunha

et al. 2002

Journal of Solid State Chemistry

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

“…The cation order parameter proposed by Augsburger et al (13) for columbite samples will be used here to quantify the cation order percentage.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Coexistence of Rutile and Trirutile Phases in a Natural Tapiolite Sample

Kinast

Zawislak

Cunha

et al. 2002

Journal of Solid State Chemistry

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“…Experimental determinations of the degree of order in natural columbites were also obtained by Augsburger et al (1999) by means of Mössbauer spectroscopy data, and they are too in good agreement with the Equation 1. The aim of this study was to fully characterize the mechanism of formation of solid solution and cation-ordering behavior in the system MnNb 2 O 6 -FeNb 2 O 6 .…”

Section: Mixing and Ordering Behavior In Manganocolumbite-ferrocolumbmentioning

confidence: 88%

Mixing and ordering behavior in manganocolumbite-ferrocolumbite solid solution: A single-crystal X-ray diffraction study

Tarantino

Zema

2005

American Mineralogist

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The structural changes upon cation substitution in natural AB 2 O 6 columbites have been studied by means of single-crystal X-ray diffraction. Most of the structural variations across the MnNb 2 O 6 -FeNb 2 O 6 solid solution in completely ordered samples can be simply understood in terms of ionic radii. The substitution of Fe for the larger Mn cation causes a linear decrease of all unit-cell parameters. Going from manganocolumbite to ferrocolumbite the site A is reduced in volume and becomes less distorted. The oxygen cage around the cation assumes a more regular arrangement since the mismatch between A and B chains decreases. At the same time, the divalent cation moves toward the barycenter of the polyhedron. The B site, which is not involved in the Fe-Mn cation substitution, maintains its geometry unchanged. Ordering of divalent cations at A sites and pentavalent cations at B sites causes linear variations of a and c cell parameters. A non-linear behavior is shown by the b cell parameter that shows a minimum at order parameter Q m ∼ 0.7. A discontinuity at this Q m value is also shown by other structural parameters. Cation ordering also causes volume variations of the two octahedral sites as a consequence of the different ionic radii of the various species. Octahedral bond-length distortion parameters show that the B site is in general more distorted than the A site; distortion of the B site increases with ordering due to higher cation-cation repulsion along the B octahedral chain and to the second-order Jahn-Teller (SOJT) effect. Octahedral chains respond to modifi cations of the polyhedra by folding along the common edge.

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Room temperature Mössbauer characterization of ferrites with spinel structure

Wang

Yang

et al. 2008

Materials Characterization

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Mössbauer Assessment of Cation Disorder in Columbite–Tantalite Minerals

Cited by 7 publications

References 5 publications

Coexistence of Rutile and Trirutile Phases in a Natural Tapiolite Sample

Coexistence of Rutile and Trirutile Phases in a Natural Tapiolite Sample

Mixing and ordering behavior in manganocolumbite-ferrocolumbite solid solution: A single-crystal X-ray diffraction study

Room temperature Mössbauer characterization of ferrites with spinel structure

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