A B S T R A C T:Eight illites were studied by M6ssbauer spectroscopy at room temperature and 4.2 K. On the basis of their Fe contents, these illites can be divided into an Fe-rich (>5 wt% Fe) and an Fe-poor (<1 to -3 wt% Fe) group. M6ssbauer spectroscopy showed that the Fe-rich illites had lower proportions of divalent Fe than their Fe-poor counterparts. Slow paramagnetic relaxation was observed in the Fe-poor illites and must be accounted for when fitting the spectra. Two samples contained iron oxides that were superparamagnetic and thus, although contributing to the Fe 3+ doublets, escaped detection at room temperature. Structural Fe 3+ had a temperature-independent quadrupole splitting that was lower for the Ferich illites (0.59 mm/s) than that of the Fe-poor illites (0.73 mm/s). The Fe 2 § quadrupole splittings were higher at 4.2 K than at room temperature, but the Fe-rich illites again had lower Fe 2+ quadrupole splittings both at room temperature (2.69 vs. 2.88 mm/s) and at 4.2 K (2.96 mm/s vs. 3.08 mm/s). Distinction of Fe sites in the illites with cis-and trans-OH coordination was not possible. The presence of tetrahedral Fe 3+ was observed only in the most Fe-rich sample (8.4 wt% Fe).
Figure 1. Graphic model of our sustained, interdisciplinary, regional study for attaining a holistic understanding of Sicán ceramic production. "Actors' Vision" refers to the ideas and observations of those physically carrying out the manufacturing in the replication experiments. Diagram by Izumi Shimada and Steve Mueller.
www.mrs.org/publications/bulletin
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.