Gram-scale synthesis of superparamagnetic Fe₃O₄nanocrystal clusters with long-term charge stability for highly stable magnetically responsive photonic crystals

Abstract

We report the gram-scale hydrothermal synthesis of superparamagnetic FeO CNCs with superior long-term charge stability, which are suitable building blocks for magnetically responsive photonic crystals (MRPCs) with widely, rapidly and reversibly tunable diffractions across the visible and near IR range, as well as long-term stability of photonic performances. The scalable synthesis of FeO CNCs with excellent long-term colloidal stability will facilitate their wide application in photonics, biomedicine, catalysis and other areas.

A Two-Step Strategy for Fabrication of Biocompatible 3D Magnetically Responsive Photonic Crystals

“…It was also clearly indicated they were consistent with the standard sample of nanocrystalline Fe 3 O 4 or γ-Fe 2 O 3 , and the crystallinity was satisfied. The primary crystallite size was 11.3 nm calculated from the Scherrer equation (Zhang et al, 2008; Holzwarth and Gibson, 2011; Yang et al, 2016) based on the strongest (311) peak which was smaller than that of the critical size of the superparamagnetic-ferromagnetic transition (30 nm for Fe 3 O 4 ). That is the main reason for maintaining the superparamagnetic property of the SMNs to increase their magnetic response and magnetic interaction.…”

Preparation and Application of Iron Oxide Nanoclusters

“…Iron oxide nanoclusters have been explored for numerous applications [3,28], including rapid magnetic separation [29], MRI contract agents with enhanced sensitivity [30], nanocarriers with high drug loading capacity [16], and magnetically responsive photonic crystals [6,9,31]. The following section will discuss these applications of magnetic nanoclusters in detail to present their potentials as functional materials with improved performance.…”

“…Under magnetic fields, these nanoclusters assemble into chain-like structures and diffract visible light. Therefore, these nanoclusters are used as building blocks to develop magnetically controlled photonic crystals [6,9,31]. The color of diffracted light can be tuned through adjustments to nanocluster size, interspacing between nanoclusters, and the strength of the applied magnetic fields.…”

Selective magnetometry of superparamagnetic iron oxide nanoparticles in liquids

“…[9][10][11][12][13] The majority of these studies, however, were performed on dry nanoparticles, which greatly simplifies the estimation of particle size, chemical composition and magnetic properties. However, in a suspension, the native environment for colloidal synthesis and storage of superparamagnetic iron oxide nanoparticles (SPION), 14,15 this approach is insufficient due to the uncertainty in separation of paramagnetic response of small particles from that of the diamagnetic background of carrier liquid. Therefore, it is usually not possible to determine the density of the smallest particles.…”

“…[16][17][18] Hence, it is clear that the analysis of in situ magnetization of SPION in suspensions is needed for accurately ascertaining the functionality of magnetic liquids. 5,6,14,15,[19][20][21][22][23][24] In response to these needs, several new methods based on photon scattering and resonant spectroscopies have recently been developed. [25][26][27][28][29][30] In parallel, methodology for the interpretation of volume magnetic data has advanced significantly and become indispensable for the precise determination of particle size distribution.…”