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Magnetic properties of liquid-phase sintered CoFe₂O₄ for application in magnetoelastic and magnetoelectric transducers.

de Brito VL, Cunha SA, Lemos LV, Nunes CB - Sensors (Basel) (2012)

Bottom Line: Bi(2)O(3) was added to the ferrite in amounts ranging from 0.25 mol% to 0.45 mol% and samples were sintered at 900 °C and 950 °C.It was observed the presence of Bi-containing particles in the microstructure of the sintered samples and the magnetostriction results indicated microstructural anisotropy.It was verified that it is possible to get dense cobalt ferrites, liquid-phase sintered, with relative densities higher than 90% and with magnetostriction values very close to samples sintered without additives.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Estudos Avançados, Rodovia dos Tamoios, km 5,5, Putim, São José dos Campos, SP 12228-001, Brazil. vlobrito@ieav.cta.br

ABSTRACT
Cobalt ferrite is a ferrimagnetic magnetostrictive ceramic that has potential application in magnetoelastic and magnetoelectric transducers. In this work, CoFe(2)O(4) was obtained using a conventional ceramic method and Bi(2)O(3) was used as additive in order to obtain liquid-phase sintered samples. Bi(2)O(3) was added to the ferrite in amounts ranging from 0.25 mol% to 0.45 mol% and samples were sintered at 900 °C and 950 °C. It was observed the presence of Bi-containing particles in the microstructure of the sintered samples and the magnetostriction results indicated microstructural anisotropy. It was verified that it is possible to get dense cobalt ferrites, liquid-phase sintered, with relative densities higher than 90% and with magnetostriction values very close to samples sintered without additives.

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Microstructures of the liquid-phase sintered ferrites (a–d) and (e) reference sample. The Bi-containing particles are indicated by the red circles.
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f2-sensors-12-10086: Microstructures of the liquid-phase sintered ferrites (a–d) and (e) reference sample. The Bi-containing particles are indicated by the red circles.

Mentions: The microstructures of the samples that attained D > 90% are shown on Figure 2, together with that of the reference sample. The liquid-phase sintered ferrites presented a non-uniform grain size and the presence of white second-phase particles was observed. The results from EDX analysis, which was carried out in one white particle per sample, are shown on Figure 3. They indicate that these particles contain Fe, Co, and Bi, that probably crystallized from the additive liquid state. The Bi fraction of the particle analyzed in the sample sintered at 900 °C was undoubtedly higher than the fractions found in the samples sintered at 950 °C. In this sample sintered at lower temperature, it is possible that some Bi2O3, which is a diamagnetic substance [18], remained after sintering.


Magnetic properties of liquid-phase sintered CoFe₂O₄ for application in magnetoelastic and magnetoelectric transducers.

de Brito VL, Cunha SA, Lemos LV, Nunes CB - Sensors (Basel) (2012)

Microstructures of the liquid-phase sintered ferrites (a–d) and (e) reference sample. The Bi-containing particles are indicated by the red circles.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3472817&req=5

f2-sensors-12-10086: Microstructures of the liquid-phase sintered ferrites (a–d) and (e) reference sample. The Bi-containing particles are indicated by the red circles.
Mentions: The microstructures of the samples that attained D > 90% are shown on Figure 2, together with that of the reference sample. The liquid-phase sintered ferrites presented a non-uniform grain size and the presence of white second-phase particles was observed. The results from EDX analysis, which was carried out in one white particle per sample, are shown on Figure 3. They indicate that these particles contain Fe, Co, and Bi, that probably crystallized from the additive liquid state. The Bi fraction of the particle analyzed in the sample sintered at 900 °C was undoubtedly higher than the fractions found in the samples sintered at 950 °C. In this sample sintered at lower temperature, it is possible that some Bi2O3, which is a diamagnetic substance [18], remained after sintering.

Bottom Line: Bi(2)O(3) was added to the ferrite in amounts ranging from 0.25 mol% to 0.45 mol% and samples were sintered at 900 °C and 950 °C.It was observed the presence of Bi-containing particles in the microstructure of the sintered samples and the magnetostriction results indicated microstructural anisotropy.It was verified that it is possible to get dense cobalt ferrites, liquid-phase sintered, with relative densities higher than 90% and with magnetostriction values very close to samples sintered without additives.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Estudos Avançados, Rodovia dos Tamoios, km 5,5, Putim, São José dos Campos, SP 12228-001, Brazil. vlobrito@ieav.cta.br

ABSTRACT
Cobalt ferrite is a ferrimagnetic magnetostrictive ceramic that has potential application in magnetoelastic and magnetoelectric transducers. In this work, CoFe(2)O(4) was obtained using a conventional ceramic method and Bi(2)O(3) was used as additive in order to obtain liquid-phase sintered samples. Bi(2)O(3) was added to the ferrite in amounts ranging from 0.25 mol% to 0.45 mol% and samples were sintered at 900 °C and 950 °C. It was observed the presence of Bi-containing particles in the microstructure of the sintered samples and the magnetostriction results indicated microstructural anisotropy. It was verified that it is possible to get dense cobalt ferrites, liquid-phase sintered, with relative densities higher than 90% and with magnetostriction values very close to samples sintered without additives.

Show MeSH