Influence of heat-treatment environment on Ni-ferrite nanoparticle formation from coconut water precursor

• Published in: Journal of materials science Vol. 48; no. 4; pp. 1543 - 1554
• Main Authors: Muniz, E. P., Proveti, J. R. C., Pereira, R. D., Segatto, B., Porto, P. S. S., Nascimento, V. P., Schettino, M. A., Passamani, E. C.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01-02-2013; Springer; Springer Nature B.V
• Subjects: Annealing; Boron nitride; Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Crystal structure; Crystallography and Scattering Methods; Heat treatment; High temperature; Iron compounds; Materials Science; Mossbauer spectroscopy; Nanocomposites; Nanomaterials; Nanoparticles; Nanostructure; Nanotechnology; Nickel ferrites; Polymer Sciences; Sol-gel processes; Solid Mechanics; Spinel; Spinel group; NiFe2O4 Nanoparticles; NiFe2O4; Bear Nitrate Powder; Coconut Water; Nickel Ferrite
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-012-6910-4

The kinetics of formation of NiFe
2
O
4
nanoparticles were investigated where the nanoparticles were produced by the proteic-sol–gel method using coconut water followed by annealing in (i) air, (ii) air in the presence of boron nitride (BN), or (iii) nitrogen. The sample dried at 473 K for 5.5 h was composed of small disordered NiFe
2
O
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nanoparticles in a superparamagnetic state as determined from Mössbauer spectroscopy. In general, heat treatment at high temperature leads to a nanocomposite rich in NiFe
2
O
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. In air, annealing at 1173 K for 8 h favored the formation of the magnetically ordered NiFe
2
O
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inverse spinel structure, with bulk characteristics and average crystal sizes of approximately 66 nm. In a nitrogen atmosphere and in compacted BN powder under air atmosphere, the NiFe
2
O
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spinel structure stabilized for temperatures up to 873 and 773 K, respectively, however, decomposition of the NiFe
2
O
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phase into other undesired structures was observed above 873 K.