(ORDO NEWS) — A team of scientists from the Chinese Academy of Sciences used aberration-corrected transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS), and scanning transmission electron microscopy (STEM) to study the nano/atomic scale microstructure and chemical composition of 25 soil grains (size 1- 3 µm) from lunar sample CE5C0400YJFM00507 (1.5 g).
The sample mainly contains the minerals olivine, pyroxene, anorthite and glass beads. To avoid possible chemical contamination and amorphization caused by ion bombardment, the team did not use a focused ion beam (FIB) to cut bulk samples, with the exception of a glass bead.
The scientists identified nanoparticles of wustite FeO instead of nanophase Fe, which are embedded in amorphous SixOy rims outside the olivine grains.
Considering that nanophase Fe is the final decomposition product of olivine Fe2SiO4, the researchers suggest that wustite FeO can serve as an intermediate state of the thermal decomposition process, and then FeO can be transformed into nanophase Fe under the influence of cosmic radiation or solar flares.
For pyroxene and anorthite, the chemical composition of the surface areas is identical to the inner parts. Meanwhile, no traces of solar flares and extraneous volatile elements were found on the surface or inside olivine and other minerals.
The results of the study indicate that the studied samples are not subject to severe space weathering.
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