Download Abstracts Book - DF-UFPE Pessoal
Download Abstracts Book - DF-UFPE Pessoal
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POSTER CONTRIBUTIONS<br />
Hematite sub-micron hollow spheres: Thermal formation and<br />
magnetic properties<br />
Luis De Los Santos Valladares 1,2 , L. León-Félix. 3,4 , A. Bustamante 3 , M. Espinoza Suárez 3 , J.<br />
Albino Aguiar 2<br />
1<br />
Cavendish Laboratory, Department of Physics, University of Cambridge, J.J. Thomson<br />
Avenue, Cambridge CB3 0HE, United Kingdom.<br />
2<br />
Laboratório de Supercondutividade e Materiais Avançados, Departamento de Física,<br />
Universidade Federal de Pernambuco 50760-901, Recife, Brazil.<br />
3<br />
Laboratorio de Cerámicos y Nanomateriales, Facultad de Ciencias Físicas, Universidad<br />
Nacional Mayor de San Marcos, Ap. Postal 14-0149, Lima, Perú.<br />
4 Núcleo de Física Aplicada, Instituto de Física, Universidade de Brasília, Brasília, <strong>DF</strong> 70910-<br />
900, Brazil.<br />
In this work, we report the thermal formation and magnetic properties of α-Fe 2 O 3 submicron<br />
hollow spheres. X-ray diffraction analysis confirms the formation of the α-Fe 2 O 3<br />
phase after sintering at 773, 823 and 823 K. Scanning electron microscopy images<br />
reveal the formation of hollow spheres after the sintering at 823 K. The evolution of the<br />
Morin transition is studied by magnetic measurements. Mössbauer spectroscopy<br />
measurements at room temperature and 77 K show that the hyperfine parameters depend<br />
on the temperature of annealing and indicate the occurrence of the Morin transition in<br />
the hollow spheres.<br />
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