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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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Magnetostriction of the liquid-phase sintered samples. Red curves: λ//; blue curves: λ⊥.
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f4-sensors-12-10086: Magnetostriction of the liquid-phase sintered samples. Red curves: λ//; blue curves: λ⊥.

Mentions: Figure 4 shows the magnetostriction vs. applied field results of the liquid-phase sintered ferrite samples. The λ// values obtained are in the range from −122 ppm to −172 ppm and are in good agreement with the result of −131 to −165 ppm obtained in [13], although the present results vary within a slightly wider range. In Table 2, the values of (λ//)s, (λ⊥)s, λtot and (λ//)s /(λ⊥)s are compiled together. The parameter λtot of the liquid-phase sintered samples ranged from −194 to −234 ppm and the reference sample had a λtot of −228 ppm, which is within this range. The total magnetostriction λtot is directly related to the saturation magnetostriction λs, which is an intrinsic material property, through the relation λtot = 3/2 λs. From the results on Table 2, we conclude that the addition of 0.35% of Bi2O3 and sintering temperature of 950 °C during 3 h, resulted in the highest intrinsic magnetostriction value.


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)

Magnetostriction of the liquid-phase sintered samples. Red curves: λ//; blue curves: λ⊥.
© Copyright Policy
Related In: Results  -  Collection

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

f4-sensors-12-10086: Magnetostriction of the liquid-phase sintered samples. Red curves: λ//; blue curves: λ⊥.
Mentions: Figure 4 shows the magnetostriction vs. applied field results of the liquid-phase sintered ferrite samples. The λ// values obtained are in the range from −122 ppm to −172 ppm and are in good agreement with the result of −131 to −165 ppm obtained in [13], although the present results vary within a slightly wider range. In Table 2, the values of (λ//)s, (λ⊥)s, λtot and (λ//)s /(λ⊥)s are compiled together. The parameter λtot of the liquid-phase sintered samples ranged from −194 to −234 ppm and the reference sample had a λtot of −228 ppm, which is within this range. The total magnetostriction λtot is directly related to the saturation magnetostriction λs, which is an intrinsic material property, through the relation λtot = 3/2 λs. From the results on Table 2, we conclude that the addition of 0.35% of Bi2O3 and sintering temperature of 950 °C during 3 h, resulted in the highest intrinsic magnetostriction value.

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