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The elusive ettringite under the high‐vacuum SEM – a reflection based on natural samples, the use of Monte Carlo modelling of EDS analyses and an extension to the ettringite group minerals
Author(s) -
THIÉRY VINCENT,
TRINCAL VINCENT,
DAVY CATHERINE A.
Publication year - 2017
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1111/jmi.12589
Subject(s) - ettringite , scanning electron microscope , energy dispersive x ray spectroscopy , monte carlo method , spectroscopy , cement , mineralogy , chemistry , materials science , chemical engineering , metallurgy , composite material , physics , engineering , portland cement , statistics , mathematics , quantum mechanics
Summary Ettringite, Ca 6 Al 2 (SO 4 ) 3 (OH) 12 .26H 2 O, or C 6 A S ¯ 3 H 32 as it is known in cement chemistry notation, is a major phase of interest in cement science as an hydration product and in polluted soil treatment since its structure can accommodate with many hazardous cations. Beyond those anthropogenic features, ettringite is first of all a naturally occurring mineral (although rare). An example of its behaviour under the scanning electron microscope and during energy dispersive spectroscopy (EDS) qualitative analysis is presented, based on the study of natural ettringite crystals from the N'Chwaning mine in South Africa. Monte Carlo modelling of the electron‐matter interaction zone at various voltages is presented and confronted with actual, observed beam damage on crystals, which burst at the analysis spot. Finally, theoretical energy dispersive spectroscopy spectra for all the ettringite group minerals have been computed as well as Monte Carlo modelling of the electron‐matter interaction zone. The knowledge of the estimation of the size of this zone may thus be helpful for the understanding of energy dispersive spectroscopy analysis in cement pastes or ettringite‐remediated soils.