X‐Ray micro‐Computed Tomography and micro X‐ray Fluorescence mapping of synthetic emerald by using a laboratory polycapillary optics X‐ray tube layout

Abstract

This paper relates the X-ray micro-Computed Tomography and micro X-ray Fluorescence 2D mapping of a\ud synthetic emerald performed by a conventional X-ray source matched with polycapillary optics. The investigated\ud crystals were synthesized in 1888 by Hautefeuille and Perrey starting from a stochiometric oxide mixture and using\ud LiMoO4 as a flux; Cr was added to the system to give the green-color to the resulting crystals. Preliminary scanning\ud electron microscope-backscattered electron images, coupled with wavelength-dispersive spectrometry microanalyses,\ud showed a peculiar ‘hourglass’ distribution of Cr across the beryl crystals. In this contribution, we show the\ud capability of a laboratory polycapillary lenses/X-ray tubes layout to characterize at the micrometric scale; the 3D spatial\ud distribution of Cr in these emerald crystals. Actually, this technique offers many opportunities to characterize natural and\ud technological materials where zoning of particular chemical elements occur at the micron or sub-micron scale

FTIR imaging in diffusion studies: CO2 and H2O in a synthetic sector-zoned beryl

“…Batches of these syntheses are currently kept in the mineralogical collection of Muséum National d'Histoire Naturelle in Paris (MNHN), and some grains were kindly donated to us to be used for scientific research. The batch consists of fairly large (up to 1.0 × 0.5 mm) emerald-green prismatic crystals; preliminary SEM-BSE analyses typically showed a particular hourglass zoning of Cr ( Figure 1B, see also Liedl et al, 2015), a feature that had already been described by Bellatreccia et al (2008) for grains coming from a different batch kept at the Museum of Mineralogy of University La Sapienza (Rome).…”

“…Figure 3B indicates that, as already discussed above, the hourglass zoning is essentially visible due to the Cr 3+ distribution across the crystal; in particular comparing Figures 3A,B it is possible to observe that the Cr 3+ zoning is also mainly responsible for the difference in birefringence in the different sides of the grain: higher birefringence (darker-yellow colors in Figure 3A) is associated with higher Cr content, while a lower Cr content is associated with a lower birefringence (pale yellow/white in Figure 3A). Such a distribution has been recently characterized in 3D by Liedl et al (2015) on a crystal from the same batch and later used for microchemical analyses (see below) using μ-CT X-ray tomography.…”

Raman and Photoluminescence Mapping of Gem Materials

“…While this article has focused on several gemological applications and scientific research using Raman and PL mapping, other applications on gem materials not recounted here have also been studied [78][79][80][81][82][83][84]. Additionally, similar research aims have involved other mapping technologies such as IR absorption mapping [85][86][87][88][89], cathodoluminescence mapping [90][91][92][93][94][95], chemical analysis using LIBS [96] or X-ray fluorescence [97], electron paramagnetic resonance (EPR) imaging [98], and fluorescence decay (luminescence lifetime) mapping [99,100]. In the future, we expect that instrumentation will be able to integrate these various technologies together.…”

Advanced channeling technologies for X-ray applications

“…As known based on X-ray channeling inside hollow tubes polyCO technology has been developed since the middle of 1980 s. PolyCO presently is one of the most powerful X-ray instrument to handle X-ray beams (shaping and focusing). The optics has shown high efficiency once applied in optimized X-ray experiments (Hampai et al, 2008(Hampai et al, , 2009(Hampai et al, , 2011(Hampai et al, , 2013a(Hampai et al, , 2013b(Hampai et al, , 2015(Hampai et al, , 2017Allocca et al, 2010;Marchitto et al, 2013Marchitto et al, , 2015Polese et al, 2014;Liedl et al, 2015;Bonfigli et al, 2016;Cherepennikov et al, 2017). For instance, one should underline a high potentiality in applications for X-ray fluorescence and diffraction analyses, for X-ray imaging, etc.…”