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Magnetic iron oxides from a tuffite from Alto Paranaíba, state of Minas Gerais, Brazil

The Mössbauer analysis along with the structural Rietveld refinement based on powder X-ray data for the magnetic fraction (saturation magnetization, sigma = 19 J T-1 kg-1) separated from a tuffite material from Alto Paranaíba, state of Minas Gerais, Brazil, reveal that a (Ti, Mg)-rich maghemite (deduced sigma = 17 J T-1 kg-1) and, for the first time observed in this lithodomain, magnesioferrite (characteristic sigma = 21 J T-1 kg-1) respond for the magnetization of the rock material. Consistent models for the ionic distribution in these iron-rich spinel structures are proposed.

magnesioferrite; Rietveld; Mössbauer


Sociedade Brasileira de Química Instituto de Química, Universidade Estadual de Campinas (Unicamp), CP6154, 13083-0970 - Campinas - SP - Brazil
E-mail: quimicanova@sbq.org.br