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oai:docta.ucm.es:20.500.14352/182102024-09-03T14:04:21Zcom_20.500.14352_14col_20.500.14352_15

00925njm 22002777a 4500 dc López Sánchez, Jesús author McIntosh, G. author Osete López, María Luisa author Campo García, A. del author Villalain, J.J. author Pérez García, Lucas author Kovacheva, M. author Rodríguez De La Fuente, Óscar author 2017-07 The identification of epsilon iron oxide (-Fe2O3) as the low Curie temperature high coercivity stable phase (HCSLT) carrying the remanence in heated archeological samples has been achieved in samples from two archeological sites that exhibited the clearest evidence of the presence of the HCSLT. This uncommon iron oxide has been detected by Confocal Raman Spectroscopy (CRS) and characterized by rock magnetic measurements. Large numbers of -Fe2O3 microaggregates (in CO) or isolated clusters (in HEL) could be recognized, distributed over the whole sample, and embedded within the ceramic matrix, along with hematite and pseudobrookite and with minor amounts of anatase, rutile, and maghemite. Curie temperature estimates of around 170 degrees C for CO and 190 degrees C for HEL are lower than for pure, synthetic -Fe2O3 (227 degrees C). This, together with structural differences between the Raman spectra of the archeologically derived and synthetic samples, is likely due to Ti substitution in the -Fe2O3 crystal lattice. The -Fe2O3--Fe2O3--Fe2O3 transformation series has been recognized in heated archeological samples, which may have implications in terms of their thermal history and in the factors that govern the formation of -Fe2O3. 1525-2027 10.1002/2017GC006929 https://hdl.handle.net/20.500.14352/18210 http://dx.doi.org/10.1002/2017GC006929 http://onlinelibrary.wiley.com Epsilon iron oxide: Origin of the high coercivity stable low Curie temperature magnetic phase found in heated archeological materials