Surface segregation in SnO2-Fe2O3 nanopowders and effects in mossbauer spectroscopy - Castro, Ricardo Hauch Ribeiro de; Hidalgo Falla, Maria del Pilar; Coaquira, José Antonio Huamaní; Bettini, Jefferson; Zanchet, Daniela; Gouvêa, Douglas (European Journal Inorganic Chemistry, 2005)