Jacobsite is a relatively rare mineral of composition MnFe2O4, found in Urandi (Bahia State) in Brazil. It is also a common species in the deep-sea manganese nodules, attracting the interest of many mineral-extracting companies. Because of its spinel constitution similar to magnetite, Jacobsite is commonly called a manganese-ferrite. However, the manganese/iron content may vary substantially according to its origin, demanding specific studies in each case. The Jacobsite mineral inspired our laboratory synthesis of the analogous manganese ferrite nanoparticles. The direct synthesis by the coprecipitation method has not been successful; however, it can be carried in the presence of citrate ions, yielding strongly magnetic nanoparticles, with a maximum magnetization of 45.6 emu.g1. Although they were structurally identical to Jacobsite, the mineral from Bahia exhibited a rather weak magnetism, because it involves a ferrimagnetic coupling. For this reason, the synthetic method seems to provide a better way of obtaining strongly magnetic manganese ferrites. These magnetic nanoparticles have been investigated in detail, including their interaction with diatoms, providing interesting magnetic bio-silicate carriers in drug delivery.
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http://dx.doi.org/10.1590/0001-3765202420240234 | DOI Listing |
An Acad Bras Cienc
September 2024
Universidade de São Paulo, Instituto de Química, Av. Prof. Lineu Prestes, 748, Cidade Universitária, 05508-000 São Paulo, SP, Brazil.
Jacobsite is a relatively rare mineral of composition MnFe2O4, found in Urandi (Bahia State) in Brazil. It is also a common species in the deep-sea manganese nodules, attracting the interest of many mineral-extracting companies. Because of its spinel constitution similar to magnetite, Jacobsite is commonly called a manganese-ferrite.
View Article and Find Full Text PDFSpectrochim Acta A Mol Biomol Spectrosc
March 2021
Department of Analytical Chemistry, Faculty of Science and Technology, University of the Basque Country UPV/EHU, Leioa, Spain; Unesco Chair on Cultural Landscape and Heritage, University of the Basque Country UPV/EHU, Vitoria‑Gasteiz, Spain.
This work summarizes the spectroscopic-assisted archaeometric study of the most important terracotta statue of Poseidonia-Paestum (Italy), the so-called Zeus Enthroned (VI sec. BC). The selected analytical strategy combines the mineralogical and molecular information provided by X-Ray diffraction (XRD) and Raman analysis with the elemental data obtained from X-Ray fluorescence (XRF) and Scanning Electron Microscopy coupled to Energy Dispersive Spectrometry (SEM/EDS).
View Article and Find Full Text PDFMicroscopy (Oxf)
December 2020
Institute of Classical Archaeology, University of Texas at Austin, 3925 W Braker Lane R1500, Austin, TX 78759, USA.
Sherds of ancient ceramics potteries, dating back to the seventh century BC and excavated from southern Italy, were analyzed in terms of microstructure and porosity (SEM), elemental composition (EDX), chemical bonding and mineralogical components (FTIR) in order to establish correlation with firing temperature, firing condition and provenance. Si/Al ratio from EDX analysis showed three major categories of raw materials (illite/montmorillonite, kaolinite and mullite), suggesting difference in provenance. Uniformly sized silica nanoparticle (0.
View Article and Find Full Text PDFMicrosc Microanal
June 2018
8Museu Nacional de Arte Antiga (MNAA),Rua das Janelas Verdes,1249-017 Lisboa,Portugal.
This work explores the combination of µ-Raman spectroscopy and scanning electron microscopy with X-ray energy dispersive spectrometry (SEM-EDS) for the study of the glazes in 15th-16th century Hispano-Moresque architectural tiles. These are high lead glazes that can be tin-opacified or transparent, and present five colors: tin-white, cobalt-blue, copper-green, iron-amber, and manganese-brown. They are generally homogenous and mineral inclusions are mostly concentrated in the glaze-ceramic interface.
View Article and Find Full Text PDFJ Colloid Interface Sci
June 2013
The University of Texas Pan-American, Department of Chemistry, Edinburg, TX 78539, United States.
Removal of chromium(III) or (VI) from aqueous solution was achieved using Fe3O4, and MnFe2O4 nanomaterials. The nanomaterials were synthesized using a precipitation method and characterized using XRD. The size of the nanomaterials was determined to be 22.
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