Preparation and crystallization of hollow α-Fe2O3 microspheres following the gas-bubble template method

L. De Los Santos Valladares; L. León Félix; S. M. Espinoza Suarez; A. G. Bustamante Dominguez; T. Mitrelias; S. Holmes; N. O. Moreno; J. Albino Aguiar; C. H.W. Barnes

doi:10.1016/j.matchemphys.2015.11.021

Preparation and crystallization of hollow α-Fe₂O₃ microspheres following the gas-bubble template method

L. De Los Santos Valladares, L. León Félix, S. M. Espinoza Suarez, A. G. Bustamante Dominguez, T. Mitrelias, S. Holmes, N. O. Moreno, J. Albino Aguiar, C. H.W. Barnes

Research output: Contribution to journal › Article › peer-review

16 Scopus citations

Abstract

In this work we report the formation of hollow α-Fe₂O₃ (hematite) microspheres by the gas-bubble template method. This technique is simple and it does not require hard templates, surfactants, special conditions of atmosphere or complex steps. After reacting Fe(NO₃)₃.9H₂O and citric acid in water by sol-gel, the precursor was annealed in air at different temperatures between 180 and 600 °C. Annealing at 550 and 600 °C generates bubbles on the melt which crystallize and oxidizes to form hematite hollow spheres after quenching. The morphology and crystal evolution are studied by means of X-ray diffraction and scanning electron microscopy. We found that after annealing at 250-400 °C, the sample consist of a mixture of magnetite, maghemite and hematite. Single hematite phase in the form of hollow microspheres is obtained after annealing at 550 and 600 °C. The crystallization and crystal size of the hematite shells increase with annealing temperature. A possible mechanism for hollow sphere formation is presented.

Original language	English
Pages (from-to)	21-27
Number of pages	7
Journal	Materials Chemistry and Physics
Volume	169
DOIs	https://doi.org/10.1016/j.matchemphys.2015.11.021
State	Published - 1 Feb 2016
Externally published	Yes

Bibliographical note

Publisher Copyright:
© 2015 Published by Elsevier B.V.

Keywords

Crystal growth
Magnetic materials
Nanostructures
Oxides
X-ray diffraction

Access to Document

10.1016/j.matchemphys.2015.11.021

Cite this

Valladares, L. D. L. S., León Félix, L., Espinoza Suarez, S. M., Bustamante Dominguez, A. G., Mitrelias, T., Holmes, S., Moreno, N. O., Albino Aguiar, J., & Barnes, C. H. W. (2016). Preparation and crystallization of hollow α-Fe₂O₃ microspheres following the gas-bubble template method. Materials Chemistry and Physics, 169, 21-27. https://doi.org/10.1016/j.matchemphys.2015.11.021

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abstract = "In this work we report the formation of hollow α-Fe2O3 (hematite) microspheres by the gas-bubble template method. This technique is simple and it does not require hard templates, surfactants, special conditions of atmosphere or complex steps. After reacting Fe(NO3)3.9H2O and citric acid in water by sol-gel, the precursor was annealed in air at different temperatures between 180 and 600 °C. Annealing at 550 and 600 °C generates bubbles on the melt which crystallize and oxidizes to form hematite hollow spheres after quenching. The morphology and crystal evolution are studied by means of X-ray diffraction and scanning electron microscopy. We found that after annealing at 250-400 °C, the sample consist of a mixture of magnetite, maghemite and hematite. Single hematite phase in the form of hollow microspheres is obtained after annealing at 550 and 600 °C. The crystallization and crystal size of the hematite shells increase with annealing temperature. A possible mechanism for hollow sphere formation is presented.",

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AU - León Félix, L.

AU - Espinoza Suarez, S. M.

AU - Bustamante Dominguez, A. G.

AU - Mitrelias, T.

AU - Holmes, S.

AU - Moreno, N. O.

AU - Albino Aguiar, J.

AU - Barnes, C. H.W.

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N2 - In this work we report the formation of hollow α-Fe2O3 (hematite) microspheres by the gas-bubble template method. This technique is simple and it does not require hard templates, surfactants, special conditions of atmosphere or complex steps. After reacting Fe(NO3)3.9H2O and citric acid in water by sol-gel, the precursor was annealed in air at different temperatures between 180 and 600 °C. Annealing at 550 and 600 °C generates bubbles on the melt which crystallize and oxidizes to form hematite hollow spheres after quenching. The morphology and crystal evolution are studied by means of X-ray diffraction and scanning electron microscopy. We found that after annealing at 250-400 °C, the sample consist of a mixture of magnetite, maghemite and hematite. Single hematite phase in the form of hollow microspheres is obtained after annealing at 550 and 600 °C. The crystallization and crystal size of the hematite shells increase with annealing temperature. A possible mechanism for hollow sphere formation is presented.

AB - In this work we report the formation of hollow α-Fe2O3 (hematite) microspheres by the gas-bubble template method. This technique is simple and it does not require hard templates, surfactants, special conditions of atmosphere or complex steps. After reacting Fe(NO3)3.9H2O and citric acid in water by sol-gel, the precursor was annealed in air at different temperatures between 180 and 600 °C. Annealing at 550 and 600 °C generates bubbles on the melt which crystallize and oxidizes to form hematite hollow spheres after quenching. The morphology and crystal evolution are studied by means of X-ray diffraction and scanning electron microscopy. We found that after annealing at 250-400 °C, the sample consist of a mixture of magnetite, maghemite and hematite. Single hematite phase in the form of hollow microspheres is obtained after annealing at 550 and 600 °C. The crystallization and crystal size of the hematite shells increase with annealing temperature. A possible mechanism for hollow sphere formation is presented.

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KW - Magnetic materials

KW - Nanostructures

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