EU-03 Growth Mechanism of One-Dimensional Assemblies Consisting of Silica-Coated Magnetic Nanoparticles
Creators: Chiemi Oka
Takumi Shiojima
Junpei Sakurai and Seiichi Hata
Publisher: name: IEEE
Year: 2025

Magnetic nanoparticles (MNPs) with a high aspect ratio have attracted attention in fields such as cancer treatment, magnetic recording, and magnetic fluids because of their magnetic anisotropy, but their synthesis requires vacuum, reduction, and/or high temperature conditions. Hence, we have focused on one-dimensional (1D) assemblies of MNPs, which are expected to exhibit magnetic anisotropy as well as the high-aspect-ratio MNPs, and we have manufactured the 1D assemblies of MNPs under atmospheric pressure and room temperature conditions by silica coating of MNPs in a chain-like alignment under a uniform magnetic field [1]. In the present study, we investigated a mechanism of the growth of the 1D assemblies with the duration of the magnetic field application for the chain alignment. We calculated the length of 1D assemblies of MNPs without silica coating using MagChain [2] and compared it with the length of our 1D assemblies with silica coating. Fig. 1 shows the results of experimental and calculated lengths of 1D assemblies of MNPs with and without silica coating, respectively, depending on the duration of magnetic field application. The experimental and calculated lengths are in relatively good agreement up to 240 s, but after 240 s, the experimental length possesses larger values than the calculated length. This would be because the MNP alignment and the silica deposition occur simultaneously in addition to the experimental length including the thickness of the silica coating. Under conditions where the magnetic field application time is relatively long, as shown in Fig. 2, the 1D assemblies of MNPs coated with silica are connected leading to the form of long 1D assemblies. Therefore, since the experimental length includes the thickness of silica not only at the surface but also at gaps between short MNP chains, the length would be larger than the calculated length.References: [1] T. Shiojima et al., Japanese Journal of Applied Physics, Vol. 63, 03SP77 (2024) [2] J.S. Andreu et al., Physical Review E, Vol. 85, 036709 (2012)
Magnetic nanoparticles (MNPs) with a high aspect ratio have attracted attention in fields such as cancer treatment, magnetic recording, and magnetic fluids because of their magnetic anisotropy, but their synthesis requires vacuum, reduction, and/or high temperature conditions. Hence, we have focused on one-dimensional (1D) assemblies of MNPs, which are expected to exhibit magnetic anisotropy as well as the high-aspect-ratio MNPs, and we have manufactured the 1D assemblies of MNPs under atmospheric pressure and room temperature conditions by silica coating of MNPs in a chain-like alignment under a uniform magnetic field [1]. In the present study, we investigated a mechanism of the growth of the 1D assemblies with the duration of the magnetic field application for the chain alignment. We calculated the length of 1D assemblies of MNPs without silica coating using MagChain [2] and compared it with the length of our 1D assemblies with silica coating. Fig. 1 shows the results of experimental and calculated lengths of 1D assemblies of MNPs with and without silica coating, respectively, depending on the duration of magnetic field application. The experimental and calculated lengths are in relatively good agreement up to 240 s, but after 240 s, the experimental length possesses larger values than the calculated length. This would be because the MNP alignment and the silica deposition occur simultaneously in addition to the experimental length including the thickness of the silica coating. Under conditions where the magnetic field application time is relatively long, as shown in Fig. 2, the 1D assemblies of MNPs coated with silica are connected leading to the form of long 1D assemblies. Therefore, since the experimental length includes the thickness of silica not only at the surface but also at gaps between short MNP chains, the length would be larger than the calculated length.References: [1] T. Shiojima et al., Japanese Journal of Applied Physics, Vol. 63, 03SP77 (2024) [2] J.S. Andreu et al., Physical Review E, Vol. 85, 036709 (2012)