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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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Hysteresis curves, indicating the values of Ms and Hc for each sample.
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f6-sensors-12-10086: Hysteresis curves, indicating the values of Ms and Hc for each sample.

Mentions: Figure 6 shows the hysteresis curves of the samples. The values of 81–82 A.m2/kg for the saturation magnetization (Ms) are close to the reference sample (around 78 A.m2/kg) and are in good agreement with other works in literature [13,22]. The sample with 0.35% Bi2O3 presented the highest values of Ms and the sample with 0.45% Bi2O3, sintered at 900 °C, presented the highest coercive field (Hc). The values of Hc are influenced by the fractions of second phases and porosity, as well as the grain size; the lower sintering temperature of 900 °C probably resulted in a smaller grain size, which contributed to increasing the coercivity.


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)

Hysteresis curves, indicating the values of Ms and Hc for each sample.
© Copyright Policy
Related In: Results  -  Collection

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

f6-sensors-12-10086: Hysteresis curves, indicating the values of Ms and Hc for each sample.
Mentions: Figure 6 shows the hysteresis curves of the samples. The values of 81–82 A.m2/kg for the saturation magnetization (Ms) are close to the reference sample (around 78 A.m2/kg) and are in good agreement with other works in literature [13,22]. The sample with 0.35% Bi2O3 presented the highest values of Ms and the sample with 0.45% Bi2O3, sintered at 900 °C, presented the highest coercive field (Hc). The values of Hc are influenced by the fractions of second phases and porosity, as well as the grain size; the lower sintering temperature of 900 °C probably resulted in a smaller grain size, which contributed to increasing the coercivity.

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