Hard magnetic colloidal nanoplates with tunable size for magneto-optical applications

We have synthesized highly anisotropic plate-like nanoparticles of aluminum-substituted strontium hexaferrite via the crystallization of 4Na 2 O × 9SrO × 5.5Fe 2 O 3 × 4.5Al 2 O 3 × 4B 2 O 3 glass, achieving tunable sizes by adjusting the annealing temperature (650-750 °C). Particle sizes range from...

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Bibliographic Details
Published in:Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2024-09, Vol.12 (37), p.14865-14875
Main Authors: Chen, Jianing, Duan, Jingtong, Anokhin, Evgeny O, Xia, Zitian, Svetogorov, Roman D, Semina, Anastasia A, Nygaard, Roy R, Eliseev, Artem A, Gorbachev, Evgeny A, Trusov, Lev A
Format: Article
Language:English
Subjects:
Aluminum
Anisotropic plates
Anisotropy
Coercivity
Colloids
Crystallization
Ferrofluids
Light modulation
Magnetic fields
Magnetic properties
Motion stability
Nanoparticles
Optical properties
Particle size
Remanence
Viscoelasticity
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Summary:We have synthesized highly anisotropic plate-like nanoparticles of aluminum-substituted strontium hexaferrite via the crystallization of 4Na 2 O × 9SrO × 5.5Fe 2 O 3 × 4.5Al 2 O 3 × 4B 2 O 3 glass, achieving tunable sizes by adjusting the annealing temperature (650-750 °C). Particle sizes range from 39 nm × 4.5 nm to 90 nm × 7.1 nm. Aluminum substitution significantly increases the coercivity of the colloid particles up to 5600 Oe. These nanoparticles form stable aqueous colloids in the pH range of 2-4. The ferrofluids exhibit a strong "jalousie effect" of adjustable optical transmission in external magnetic fields. The transmission difference rises with increasing nanoplate diameter and anisotropy factor. The high remanence of the hexaferrite particles allows them to be manipulated by weak magnetic fields, providing high-frequency particle motion with available electromagnets. Tunable particle sizes facilitate specific applications: smaller particles offer higher relaxation frequencies and better stability, while larger particles provide superior light scattering and induced mechanical momentum. These properties make the nanoparticles suitable for microfluidic stirring, mechanical impacting for cancer treatment, high-frequency light modulation, optical probing of magnetic fields, and micrometer-scale viscoelasticity sensing. A method for producing highly anisotropic plate-like hexaferrite colloidal nanoparticles with tunable diameters is proposed.
ISSN:2050-7526
2050-7534
DOI:10.1039/d4tc02684e