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Application of synchrotron through-the-substrate microdiffraction to crystals in polished thin sections.

Rius J, Vallcorba O, Frontera C, Peral I, Crespi A, Miravitlles C - IUCrJ (2015)

Bottom Line: The synchrotron through-the-substrate X-ray microdiffraction technique (tts-μXRD) is extended to the structural study of microvolumes of crystals embedded in polished thin sections of compact materials [Rius, Labrador, Crespi, Frontera, Vallcorba & Melgarejo (2011 ▸).J.Synchrotron Rad. 18, 891-898].Thanks to its versatility and experimental simplicity, this method-ology should be useful for disciplines as disparate as petrology, materials science and cultural heritage.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institut de Ciència de Materials de Barcelona, CSIC, Campus de la Universitat Autònoma de Barcelona, Bellaterra, Catalonia 08193, Spain.

ABSTRACT
The synchrotron through-the-substrate X-ray microdiffraction technique (tts-μXRD) is extended to the structural study of microvolumes of crystals embedded in polished thin sections of compact materials [Rius, Labrador, Crespi, Frontera, Vallcorba & Melgarejo (2011 ▸). J.Synchrotron Rad. 18, 891-898]. The resulting tts-μXRD procedure includes some basic steps: (i) collection of a limited number of consecutive two-dimensional patterns (frames) for each randomly oriented crystal microvolume; (ii) refinement of the metric from the one-dimensional diffraction pattern which results from circularly averaging the sum of collected frames; (iii) determination of the reciprocal lattice orientation of each randomly oriented crystal microvolume which allows assigning the hkl indices to the spots and, consequently, merging the intensities of the different frames into a single-crystal data set (frame merging); and (iv) merging of the individual crystal data sets (multicrystal merging) to produce an extended data set suitable for structure refinement/solution. Its viability for crystal structure solution by Patterson function direct methods (δ recycling) and for accurate single-crystal least-squares refinements is demonstrated with some representative examples from petrology in which different glass substrate thicknesses have been employed. The section of the crystal microvolume must be at least of the same order of magnitude as the focus of the beam (15 × 15 µm in the provided examples). Thanks to its versatility and experimental simplicity, this method-ology should be useful for disciplines as disparate as petrology, materials science and cultural heritage.

No MeSH data available.


Related in: MedlinePlus

General description of the tts-μXRD technique applied to multiple crystal microvolumes. (a) After collecting the data from all crystal microvolumes, refining the global metric, orienting the multiple crystals and merging the sequential ϕ scans of each individual crystal (frame merging), the final data set results from merging the individual data sets (multicrystal merging). To consider possible gauge volume variations, a double scaling process is carried out (the first by scaling each frame during frame merging and the second by scaling each crystal data set during multicrystal merging, as detailed in the text). (b) The strategy for data collection for each crystal microvolume. Sequential (partially overlapping) ϕ scans are centred at the offset angles ϕi (= iΔϕ) with 2Δϕ widths. The substrate thickness limits the number of ϕ scans.
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fig2: General description of the tts-μXRD technique applied to multiple crystal microvolumes. (a) After collecting the data from all crystal microvolumes, refining the global metric, orienting the multiple crystals and merging the sequential ϕ scans of each individual crystal (frame merging), the final data set results from merging the individual data sets (multicrystal merging). To consider possible gauge volume variations, a double scaling process is carried out (the first by scaling each frame during frame merging and the second by scaling each crystal data set during multicrystal merging, as detailed in the text). (b) The strategy for data collection for each crystal microvolume. Sequential (partially overlapping) ϕ scans are centred at the offset angles ϕi (= iΔϕ) with 2Δϕ widths. The substrate thickness limits the number of ϕ scans.

Mentions: In a typical tts-μXRD experiment dealing with crystal microvolumes, the X-ray diffraction information is obtained by rotating the thin section with the selected microvolume at the origin (Fig. 2 ▸). Each ϕ scan is defined by its centre ϕi (offset angle) and the corresponding angular increment (Δϕ) (mostly between 5 and 10°). If multiple scans at different offset angles are needed, the corresponding rotation limits for a given offset angle ϕi will be [ϕi − Δϕ, ϕi + Δϕ], which for the particular choice reduce to This choice of ϕi ensures that each diffraction spot is measured twice and that a spot lying at the border of one ϕ scan falls within the neighbouring ϕ scan (Fig. 2 ▸b). Data are collected for a limited number of microvolumes of different crystals (j = 1 to N) of the same compound. According to this schema, each frame is uneqivocally characterized by the (j, Δϕ, i) triplet.


Application of synchrotron through-the-substrate microdiffraction to crystals in polished thin sections.

Rius J, Vallcorba O, Frontera C, Peral I, Crespi A, Miravitlles C - IUCrJ (2015)

General description of the tts-μXRD technique applied to multiple crystal microvolumes. (a) After collecting the data from all crystal microvolumes, refining the global metric, orienting the multiple crystals and merging the sequential ϕ scans of each individual crystal (frame merging), the final data set results from merging the individual data sets (multicrystal merging). To consider possible gauge volume variations, a double scaling process is carried out (the first by scaling each frame during frame merging and the second by scaling each crystal data set during multicrystal merging, as detailed in the text). (b) The strategy for data collection for each crystal microvolume. Sequential (partially overlapping) ϕ scans are centred at the offset angles ϕi (= iΔϕ) with 2Δϕ widths. The substrate thickness limits the number of ϕ scans.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4491317&req=5

fig2: General description of the tts-μXRD technique applied to multiple crystal microvolumes. (a) After collecting the data from all crystal microvolumes, refining the global metric, orienting the multiple crystals and merging the sequential ϕ scans of each individual crystal (frame merging), the final data set results from merging the individual data sets (multicrystal merging). To consider possible gauge volume variations, a double scaling process is carried out (the first by scaling each frame during frame merging and the second by scaling each crystal data set during multicrystal merging, as detailed in the text). (b) The strategy for data collection for each crystal microvolume. Sequential (partially overlapping) ϕ scans are centred at the offset angles ϕi (= iΔϕ) with 2Δϕ widths. The substrate thickness limits the number of ϕ scans.
Mentions: In a typical tts-μXRD experiment dealing with crystal microvolumes, the X-ray diffraction information is obtained by rotating the thin section with the selected microvolume at the origin (Fig. 2 ▸). Each ϕ scan is defined by its centre ϕi (offset angle) and the corresponding angular increment (Δϕ) (mostly between 5 and 10°). If multiple scans at different offset angles are needed, the corresponding rotation limits for a given offset angle ϕi will be [ϕi − Δϕ, ϕi + Δϕ], which for the particular choice reduce to This choice of ϕi ensures that each diffraction spot is measured twice and that a spot lying at the border of one ϕ scan falls within the neighbouring ϕ scan (Fig. 2 ▸b). Data are collected for a limited number of microvolumes of different crystals (j = 1 to N) of the same compound. According to this schema, each frame is uneqivocally characterized by the (j, Δϕ, i) triplet.

Bottom Line: The synchrotron through-the-substrate X-ray microdiffraction technique (tts-μXRD) is extended to the structural study of microvolumes of crystals embedded in polished thin sections of compact materials [Rius, Labrador, Crespi, Frontera, Vallcorba & Melgarejo (2011 ▸).J.Synchrotron Rad. 18, 891-898].Thanks to its versatility and experimental simplicity, this method-ology should be useful for disciplines as disparate as petrology, materials science and cultural heritage.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institut de Ciència de Materials de Barcelona, CSIC, Campus de la Universitat Autònoma de Barcelona, Bellaterra, Catalonia 08193, Spain.

ABSTRACT
The synchrotron through-the-substrate X-ray microdiffraction technique (tts-μXRD) is extended to the structural study of microvolumes of crystals embedded in polished thin sections of compact materials [Rius, Labrador, Crespi, Frontera, Vallcorba & Melgarejo (2011 ▸). J.Synchrotron Rad. 18, 891-898]. The resulting tts-μXRD procedure includes some basic steps: (i) collection of a limited number of consecutive two-dimensional patterns (frames) for each randomly oriented crystal microvolume; (ii) refinement of the metric from the one-dimensional diffraction pattern which results from circularly averaging the sum of collected frames; (iii) determination of the reciprocal lattice orientation of each randomly oriented crystal microvolume which allows assigning the hkl indices to the spots and, consequently, merging the intensities of the different frames into a single-crystal data set (frame merging); and (iv) merging of the individual crystal data sets (multicrystal merging) to produce an extended data set suitable for structure refinement/solution. Its viability for crystal structure solution by Patterson function direct methods (δ recycling) and for accurate single-crystal least-squares refinements is demonstrated with some representative examples from petrology in which different glass substrate thicknesses have been employed. The section of the crystal microvolume must be at least of the same order of magnitude as the focus of the beam (15 × 15 µm in the provided examples). Thanks to its versatility and experimental simplicity, this method-ology should be useful for disciplines as disparate as petrology, materials science and cultural heritage.

No MeSH data available.


Related in: MedlinePlus