Structural rationale for the occurrence of the elbow twins in cassiterite and rutile

Nespolo, M.; Souvignier, B.

doi:10.2465/jmps.150123

Cited by 9 publications

(6 citation statements)

References 29 publications

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“…An orientation variation of 68° was measured between the twin and the main orientation of the centimetric grain (Fig. A), which is close to 70°, the ideal structure (Nespolo & Souvignier, ).…”

Section: Resultssupporting

confidence: 52%

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A multimodal microcharacterisation of trace‐element zonation and crystallographic orientation in natural cassiterite by combining cathodoluminescence, EBSD, EPMA and contribution of confocal Raman‐in‐SEM imaging

Lerouge

Schmidt²

2018

Journal of Microscopy

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In cassiterite, tin is associated with metals (titanium, niobium, tantalum, indium, tungsten, iron, manganese, mercury). Knowledge of mineral chemistry and trace-element distribution is essential for: the understanding of ore formation, the exploration phase, the feasibility of ore treatment, and disposal/treatment of tailings after the exploitation phase. However, the availability of analytical methods make these characterisations difficult. We present a multitechnical approach to chemical and structural data that includes scanning electron microscopy (SEM)-based imaging and microanalysis techniques such as: secondary and backscattered electrons, cathodoluminescence (CL), electron probe microanalyser (EPMA), electron backscattered diffraction (EBSD) and confocal Raman-imaging integrated in a SEM (RISE). The presented results show the complementarity of the used analytical techniques. SEM, CL, EBSD, EPMA provide information from the interaction of an electron beam with minerals, leading to atomistic information about their composition, whereas RISE, Raman spectroscopy and imaging completes the studies with information about molecular vibrations, which are sensitive to structural modifications of the minerals. The correlation of Raman bands with the presence/absence of Nb, Ta, Fe (heterovalent substitution) and Ti (homovalent substitution) is established at a submicrometric scale. Combination of the different techniques makes it possible to establish a direct link between chemical and crystallographic data of cassiterite.

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Section: Resultssupporting

confidence: 52%

“…A similar change is observed also in the EBSD image, providing evidence of mono‐oriented grains with twinning. Twinning is well known in cassiterite as the ‘elbow twin’ (Nespolo & Souvignier, ). An orientation variation of 68° was measured between the twin and the main orientation of the centimetric grain (Fig.…”

Section: Resultsmentioning

confidence: 99%

A multimodal microcharacterisation of trace‐element zonation and crystallographic orientation in natural cassiterite by combining cathodoluminescence, EBSD, EPMA and contribution of confocal Raman‐in‐SEM imaging

Lerouge

Schmidt²

2018

Journal of Microscopy

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“…In cassiterite with the rutile-type structure, TBs along {101} planes occur frequently, while twins on {301} are seldom (Nespolo & Souvignier, 2015;Hahn & Klapper, 2006;Ramdohr, 1969). The angle between [010] axes of the domains in twinned orientation may be used to distinguish between the two twin types.…”

Section: General Characterization Of the Microstructuresmentioning

confidence: 99%

“…Hahn & Klapper, 2006). Reflection twins across the (101) plane in rutile-type structures are known as elbow or knee twins; they occur in both of the most common minerals with the rutiletype structure, rutile (TiO 2 ) and cassiterite (SnO 2 ) (Nespolo & Souvignier, 2015). Due to the four sets of equivalent {101} reflection planes (tetragonal prisms), different multiple twinning combinations are possible; they have been thoroughly described in rutile (Hahn & Klapper, 2006).…”

Section: Introductionmentioning

confidence: 99%

Twinning in SnO₂-based ceramics doped with CoO and Nb₂O₅: morphology of multiple twins revealed by electron backscatter diffraction

Padrón‐Navarta

Barou

Daneu

2020

Acta Crystallogr B Struct Sci Cryst Eng Mater

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Electron backscatter diffraction (EBSD) was used for the analysis of multiple cyclic twins in cassiterite (SnO2), which form during sintering of SnO2 with small additions of CoO and Nb2O5. Grain misorientation analysis has shown that about one third of all grains contain {101} twin boundaries (TBs). The majority of these grains are contact twins, whereas a small fraction of grains are multiple, mainly cyclic twins. A procedure was developed in MTEX [Bachmann, Hielscher & Schaeben (2010). Solid State Phenom. 160, 63–88] for automated identification of crystallographically different types of cyclic twins and found two main types: coplanar twins composed of three or four domains with a common [010] axis and alternating twins composed of three to seven domains oriented along the [111] axis. Both types of cyclic twins have a characteristic common origin (nucleus) of all TBs, which is positioned eccentric relative to the grain section and the cycle is closed with a shorter non-crystallographic contact between the first and the last twin domain. The morphology of cyclic twins suggests that they form by nucleation in the initial stages of grain growth. The average size of twinned grains increases with the number of twin domains indicating the influence of TBs formation on the growth of composite grains.

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“…Here, the matrices M i are taken following the choice of ITA (Table 5. The usefulness of these unconventional settings may seem questionable at first sight. As an example of application, we may quote the elbow twins in cassiterite and rutile (Nespolo & Souvignier, 2015), where the maximal subgroup of the crystal space group compatible with the twin lattice is of type B2 1 /e (unconventional setting of No. 13) with a monoclinic angle of 91.41 , which in the standard P2 1 /n setting (unique axis b, cell choice 2) becomes 100.83 (other cell choices correspond to an even larger angle), making the orthorhombic pseudosymmetry of the twin lattice undetected.…”

Section: Alternative Settings Of Space Groupsmentioning

confidence: 99%

The crystallographic chameleon: when space groups change skin

Nespolo

Aroyo

2016

Acta Cryst Sect A

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Volume A of International Tables for Crystallography is the reference for space-group information. However, the content is not exhaustive because for many space groups a variety of settings may be chosen but not all of them are described in detail or even fully listed. The use of alternative settings may seem an unnecessary complication when the purpose is just to describe a crystal structure; however, these are of the utmost importance for a number of tasks, such as the investigation of structure relations between polymorphs or derivative structures, the study of pseudo-symmetry and its potential consequences, and the analysis of the common substructure of twins. The aim of the article is twofold: (i) to present a guide to expressing the symmetry operations, the Hermann-Mauguin symbols and the Wyckoff positions of a space group in an alternative setting, and (ii) to point to alternative settings of space groups of possible practical applications and not listed in Volume A of International Tables for Crystallography.

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Structural rationale for the occurrence of the elbow twins in cassiterite and rutile

Cited by 9 publications

References 29 publications

A multimodal microcharacterisation of trace‐element zonation and crystallographic orientation in natural cassiterite by combining cathodoluminescence, EBSD, EPMA and contribution of confocal Raman‐in‐SEM imaging

A multimodal microcharacterisation of trace‐element zonation and crystallographic orientation in natural cassiterite by combining cathodoluminescence, EBSD, EPMA and contribution of confocal Raman‐in‐SEM imaging

Twinning in SnO₂-based ceramics doped with CoO and Nb₂O₅: morphology of multiple twins revealed by electron backscatter diffraction

The crystallographic chameleon: when space groups change skin

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Structural rationale for the occurrence of the elbow twins in cassiterite and rutile

Cited by 9 publications

References 29 publications

A multimodal microcharacterisation of trace‐element zonation and crystallographic orientation in natural cassiterite by combining cathodoluminescence, EBSD, EPMA and contribution of confocal Raman‐in‐SEM imaging

A multimodal microcharacterisation of trace‐element zonation and crystallographic orientation in natural cassiterite by combining cathodoluminescence, EBSD, EPMA and contribution of confocal Raman‐in‐SEM imaging

Twinning in SnO2-based ceramics doped with CoO and Nb2O5: morphology of multiple twins revealed by electron backscatter diffraction

The crystallographic chameleon: when space groups change skin

Contact Info

Product

Resources

About

Twinning in SnO₂-based ceramics doped with CoO and Nb₂O₅: morphology of multiple twins revealed by electron backscatter diffraction