Novel method for low temperature sintering of barium hexaferrite with magnetic easy-axis alignment

An, Guk-Hwan; Hwang, Tae-Yeon; Kim, Jongryoul; Kim, JinBae; Kang, Nam Lyong; Jeon, Kwang-Won; Kang, Min Kyu

doi:10.1016/j.jeurceramsoc.2013.10.027

Cited by 19 publications

(3 citation statements)

References 25 publications

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“…Similarly, when the weight fraction (x > 41) of NFO is increased, the composites tend to show a reduction in BaM grains. Barium ferrite itself tends to form hexagonal grains [ 23 ] and, with a tweak in the synthesis process, the particle shape can be made nearly spherical [ 24 ]. In our case, the processing has a large impact on the grain growth on these composites.…”

Section: Resultsmentioning

confidence: 99%

A Novel Spinel Ferrite-Hexagonal Ferrite Composite for Enhanced Magneto-Electric Coupling in a Bilayer with PZT

Saha,

Acharya,

Popov

et al. 2023

Sensors

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The magnetoelectric effect (ME) is an important strain mediated-phenomenon in a ferromagnetic-piezoelectric composite for a variety of sensors and signal processing devices. A bias magnetic field, in general, is essential to realize a strong ME coupling in most composites. Magnetic phases with (i) high magnetostriction for strong piezomagnetic coupling and (ii) large anisotropy field that acts as a built-in bias field are preferred so that miniature, ME composite-based devices can operate without the need for an external magnetic field. We are able to realize such a magnetic phase with a composite of (i) barium hexaferrite (BaM) with high magnetocrystalline anisotropy field and (ii) nickel ferrite (NFO) with high magnetostriction. The BNx composites, with (100 − x) wt.% of BaM and x wt.% NFO, for x = 0–100, were prepared. X-ray diffraction analysis shows that the composites did not contain any impurity phases. Scanning electron microscopy images revealed that, with an increase in NFO content, hexagonal BaM grains become prominent, leading to a large anisotropy field. The room temperature saturation magnetization showed a general increase with increasing BaM content in the composites. NFO rich composites with x ≥ 60 were found to have a large magnetostriction value of around −23 ppm, comparable to pure NFO. The anisotropy field HA of the composites, determined from magnetization and ferromagnetic resonance (FMR) measurements, increased with increasing NFO content and reached a maximum of 7.77 kOe for x = 75. The BNx composite was cut into rectangular platelets and bonded with PZT to form the bilayers. ME voltage coefficient (MEVC) measurements at low frequencies and at mechanical resonance showed strong coupling at zero bias for samples with x ≥ 33. This large in-plane HA acted as a built-in field for strong ME effects under zero external bias in the bilayers. The highest zero-bias MEVC of ~22 mV/cm Oe was obtained for BN75-PZT bilayers wherein BN75 also has the highest HA. The Bilayer of BN95-PZT showed a maximum MEVC ~992 mV/cm Oe at electromechanical resonance at 59 kHz. The use of hexaferrite–spinel ferrite composite to achieve strong zero-bias ME coupling in bilayers with PZT is significant for applications related to energy harvesting, sensors, and high frequency devices.

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Section: Resultsmentioning

confidence: 99%

A Novel Spinel Ferrite-Hexagonal Ferrite Composite for Enhanced Magneto-Electric Coupling in a Bilayer with PZT

Saha,

Acharya,

Popov

et al. 2023

Sensors

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“…Anisotropic barium hexaferrite is produced by adding NaCl salt during the sintering process at low sintering temperature. The addition of NaCl to the powder during the sintering process has proven to be an effective way in the alignment of particles along the magnetic easy-axis, but this method is limited to a certain low sintering temperature and also to a lengthy time-consumption [ 32 ]. So far, some permanent magnets coupled with SPS have been used in the alignment of sintered powders such as Sm-Co magnet with Curie temperature of 800 °C which was utilized during the sintering of Sm–Fe–N [ 33 ]; as well as Halbach magnet with a uniaxial magnetic field of 1T, which was used to assist spark plasma sintering of Co 80 Ni 20 nanowires [ 34 ]; also two commercial Sm 2 Co 17 bulk magnets (mµ0Br ≈1.10 T at 300 K, max working temperature (≈300 °C), which were utilized to assist anisotropic SPS-compacted MnBi magnets [ 35 ].…”

Section: Introductionmentioning

confidence: 99%

Process Optimization of In Situ Magnetic-Anisotropy Spark Plasma Sintering of M-Type-Based Barium Hexaferrite BaFe12O19

et al. 2021

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This paper introduces a new spark plasma sintering technique that is able to order crystalline anisotropy by in-series/in situ DC electric coupled magnetic field. The process control parameters have been investigated on the production of anisotropic BaFe12O19 magnets based on resulted remanence (Mr). Sintering holding time (H.T.), cooling rate (C.R.), pressure (P), and sintering temperature (S.T.) are optimized by Taguchi with L9 orthogonal array (OA). The remanent magnetization of nanocrystalline BaFe12O19 in parallel (Mrǁ) and perpendicular (MrꞱ) to the applied magnetic field was regarded as a measure of performance. The Taguchi study calculated optimum process parameters, which significantly improved the sintering process based on the confirmation tests of BaFe12O19 anisotropy. The magnetic properties in terms of Mrǁ and MrꞱ were greatly affected by sintering temperature and pressure according to ANOVA results. In addition, regression models were developed for predicting the Mrǁ as well as MrꞱ respectively.

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“…As a conventional permanent magnetic material, the sintering temperature of barium hexaferrites without additives could reach up to 1300º C [4], [5]. However, high temperature could increase the necking and grain growth of particles, and then degrade the magnetic properties [6]. And with the high-frequency, integrated and miniaturized development of microwave devices, more attentions to the next generation magnetic materials have been devoted to the low-temperature sintering, which is determined by the melting temperature of device's electrodes and various interdiffusion phenomena [7], [8].…”

Section: Introductionmentioning

confidence: 99%

Low-Temperature Sintering of Barium Hexaferrites With Bi<sub>2</sub>O<sub>3</sub>/CuO Additives

Zhong

et al. 2015

IEEE Trans. Magn.

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+CuO additives reach 1020º C and 920º C, respectively. As the amount of Bi 2 O 3 is 3.0wt%, the specimens of BaFe 12 O 19 show saturation magnetization (M s ) of 346kA/m, remanence (M r ) of 227kA/m and density (d) of 5.06g/cm 3 . Meanwhile, the combination of 3.0wt% Bi 2 O 3 and 3.0wt% CuO additives significantly promotes grain growth and sintering densification, with a high saturation magnetization of 371kA/m and density of 5.23g/cm 3 for BaFe 12 O 19 , which are pretty close to theoretical values (380kA/m, 5.28g/cm 3 ). Moreover, the corresponding remanence could also rise by 10% comparing to the sintered samples with 3.0wt% Bi 2 O 3 .

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Novel method for low temperature sintering of barium hexaferrite with magnetic easy-axis alignment

Cited by 19 publications

References 25 publications

A Novel Spinel Ferrite-Hexagonal Ferrite Composite for Enhanced Magneto-Electric Coupling in a Bilayer with PZT

A Novel Spinel Ferrite-Hexagonal Ferrite Composite for Enhanced Magneto-Electric Coupling in a Bilayer with PZT

Process Optimization of In Situ Magnetic-Anisotropy Spark Plasma Sintering of M-Type-Based Barium Hexaferrite BaFe12O19

Low-Temperature Sintering of Barium Hexaferrites With Bi<sub>2</sub>O<sub>3</sub>/CuO Additives

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