X-Ray Mapping and Interpretation of Scatter Diagrams

A fibrous herringbone-modified helicoidal architecture is identified within the exocuticle of an impact-resistant crustacean appendage. This previously unreported composite microstructure, which features highly textured apatite mineral templated by an alpha-chitin matrix, provides enhanced stress redistribution and energy absorption over the traditional helicoidal design under compressive loading. Nanoscale toughening mechanisms are also identified using high load nanoindentation and in-situ TEM picoindentation. A Sinusoidally-Architected Helicoidal BiocompositeBy Nicholas A. Yaraghi, Nicolás Guarín-Zapata, Lessa K. Grunenfelder, Eric Hintsala, Sanjit Bhowmick, Jon M. Hiller, Mark Betts, Edward L. Principe, Jae-Young Jung, Leigh Sheppard, Richard Wuhrer, Joanna McKittrick, Pablo D. Zavattieri Keywords: (Composites, Toughness, Impact, Biomineral, Ultrastructure) Submitted to 3 Biologically mineralized composites offer inspiration for the design of next generation structural materials due to their low density, high strength and toughness currently unmatched by engineering technologies. [1][2][3][4][5][6][7][8][9] Such properties are based on the ability for the organism to utilize structural organics and acidic proteins to guide and control the mineralization process to yield hierarchical architectures with well-defined compositional gradients.One notable example is the highly developed raptorial appendage, or dactyl, of the stomatopods, a group of aggressive marine crustaceans that use these structures for feeding upon hard-shelled and soft-bodied prey. [10][11][12][13][14] The dactyls of the "smashers", those that feed primarily on hard-shelled prey, (see Figure 1A) takes the form of a bulbous club ( Figure 1B), which is used to smash through mollusk shells, crab exoskeletons, and other tough mineralized structures with tremendous force and speed. [11][12][13][14][15][16] Achieving accelerations over 10,000g and reaching speeds of 23 m/s from rest, the dactyl strike is recognized as one of the fastest and most powerful impacting events observed in Nature. [11,12] The club is capable of delivering and subsequently enduring repetitive impact forces up to 1500 N and cavitation stresses without catastrophically failing, demonstrating its utility as an exceptionally damage-tolerant natural material.The origins of such a mechanical response lie in the structural design. Previous work identified the club as a multi-regional composite material containing an organic matrix composed of alpha-chitin fibers mineralized by amorphous forms of calcium carbonate and calcium phosphate as well as crystalline apatite. [17,18] These investigations revealed mechanisms responsible for providing damage-tolerance and impact-resistance to the club, which were largely attributed to the interior of the club (periodic region), identified as the primary energy-absorbing layer. [17,18] The combination of soft polymeric nanofibers and stiffer mineral provides a periodic modulus mismatch leading to crack deflection, which in co...

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“…X-ray maps were post-processed using the "Chemical Imaging" software package within the Moran Scientific Microanalysis System [48].…”

Section: X-ray Mappingmentioning

confidence: 99%

A Sinusoidally Architected Helicoidal Biocomposite

et al. 2016

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“…The combination of EDS and WDS produces a very powerful analytical technique also allowing for excellent quantitative X-ray mapping (QXRM) [1][2][3][4][5]. Traditionally, the EDS is used for fast elemental analysis to determine what elements are present and the WDS then utilised to acquire precise major and trace elemental quantitative analysis.…”

Section: Microanalysis (Eds and Wds)mentioning

confidence: 99%

A new life for the wavelength-dispersive X-ray spectrometer (WDS): incorporation of a silicon drift detector into the WDS for improved quantification and X-ray mapping

Wuhrer

Moran²

2018

IOP Conf. Ser.: Mater. Sci. Eng.

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Abstract. The wavelength-dispersive X-ray spectrometer (WDS) has been around for a long time and the design has not changed much since its original development. The electron microprobe operator using WDS has to be meticulous in monitoring items such as gas flow, gas purity, gas pressure, noise levels of baseline and window, gas flow proportional counter (GFPC) voltage levels, count rate suppression, anode wire contamination and other detector parameters. Recent development and improvements of silicon drift detectors (SDD's) has allowed the incorporation of a SDD as the X-ray detector in place of the proportional counter (PC) and/or gas flow proportional counter (GFPC). This allows minimal mechanical alteration and no loss of movement range. The superiority of a WDS with a SDD, referred to as SD-WDS, is easily seen once in operation. The SD-WDS removes many artefacts including the worse of all high order diffraction, thus allowing more accurate analysis. The incorporation of the SDD has been found to improve the light and mid element range and consequently improving the detection limit for these elements. It is also possible to obtain much more reliable results at high count rates with almost no change in resolution, gain and zero-peak characteristics of the energy spectrum. IntroductionThe electron probe microanalyser (EPMA) instrument has been around for a long time, which utilises the X-ray microanalysis techniques of wavelength-dispersive and energy-dispersive X-ray spectrometry (WDS and EDS). The WDS design has not changed much since its original development. WDS exhibits far better spectral resolution than the conventional EDS. The combination of EDS and WDS produces a very powerful analytical technique allowing for excellent quantitative X-ray mapping (QXRM). However, the electron microprobe operator using WDS has to be meticulous in monitoring items such as gas flow, gas purity, gas pressure, noise levels of baseline and window, gas flow proportional counter (GFPC) voltage levels, count rate suppression, anode wire contamination and other detector parameters.Over the last couple of years we have been developing and testing alternative configuration WD spectrometers, using Amptek PIN (p-intrinsic-n type diode) and silicon drift detectors (SDD's) in place of the sealed proportional counter (SPC) and gas flow proportional counters (GFPC's) respectively.

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“…Quantitative x-ray mapping (QXRM) enables reliable quantitative results that can be an order of magnitude better than traditional analysis and is also far superior to regions of interest xray maps (ROIM) where low levels of an element or elemental overlaps are present [2]. The use of scatter diagrams, rotational scatter diagrams, pseudo colouring and filtering techniques has been presented before by the authors [2][3][4]. Other information that can be obtained, which is very important and gives the user even more important information about the microstructure of their sample, is theoretical BSE maps, elemental ratio maps, atomic number-absorption-fluorescence maps (ZAF) and totals mapping.…”

mentioning

confidence: 99%

Post Processing of X-Ray Maps - Theoretical BSE Mapping, Totals Mapping and Ratio Mapping

Moran

Wuhrer

2010

Microsc Microanal

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Scanning electron microscopy (SEM), wavelength dispersive spectroscopy (WDS) and energy dispersive spectroscopy (EDS), and the combination of these techniques through x-ray mapping (XRM) has become an excellent tool for characterizing the distribution of elements and phases [1].There is so much more information that can be obtained from full spectrum maps other than just a regions of interest elemental map (ROIM). The full spectrum maps can be processed to determine important information about the microstructure and properties of the material. To obtain a better understanding of a material's chemical and microstructural properties a number of post-processing methods can be employed. This includes generating ZAF corrected quantitative x-ray maps (QXRM maps (Fig. 1). Quantitative x-ray mapping (QXRM) enables reliable quantitative results that can be an order of magnitude better than traditional analysis and is also far superior to regions of interest xray maps (ROIM) where low levels of an element or elemental overlaps are present [2]. The use of scatter diagrams, rotational scatter diagrams, pseudo colouring and filtering techniques has been presented before by the authors [2][3][4]. Other information that can be obtained, which is very important and gives the user even more important information about the microstructure of their sample, is theoretical BSE maps, elemental ratio maps, atomic number-absorption-fluorescence maps (ZAF) and totals mapping.When generating elemental x-ray maps, the computer can easily calculate the theoretical BSE coefficient by looking at the quantitative data and using this generate the BSE coefficient for each point on the map (Fig. 2). The theoretical BSE map (or image) gives us information on what is going on just below the surface of the sample. We can also ratio the real BSE to the generated BSE to pick up problems such as quantification errors, interaction problems and ZAF correction problems.Most users are aware that traditional quantitative standards based analysis involves totals in the range (99-101) which gives them an idea of accuracy of the results. This also applies to x-ray mapping. Through x-ray mapping, the totals at each point of the map can be calculated and mapped (Fig. 2). These total maps then give us an idea of the quality of the analysis and also make it easy to determine problem areas within the analysis area.Elemental ratio mapping is a powerful technique that helps to reveal subtle chemical variations in a sample and is similar to a scatter diagram for these two elements. Scatter diagrams give you correlation between one element and another in the form of an intensity histogram. Whereas, a ratio map between two elements shows the spatial distribution of this correlation (Fig. 3). Ratio maps can also be created from different combinations of elements and from the different background regions near elements of the spectra. Background ratio mapping near absorption edges can aid in determining absorption differences and is very powerful.

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X-Ray Mapping and Interpretation of Scatter Diagrams

Cited by 30 publications

References 4 publications

A Sinusoidally Architected Helicoidal Biocomposite

A Sinusoidally Architected Helicoidal Biocomposite

A new life for the wavelength-dispersive X-ray spectrometer (WDS): incorporation of a silicon drift detector into the WDS for improved quantification and X-ray mapping

Post Processing of X-Ray Maps - Theoretical BSE Mapping, Totals Mapping and Ratio Mapping

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