Comparing Highly Ordered Monolayers of Nanoparticles Fabricated Using Electrophoretic Deposition: Cobalt Ferrite Nanoparticles versus Iron Oxide Nanoparticles

Abstract

Ordered assemblies of nanoparticles remain challenging to fabricate, yet could open the door to many potential applications of nanomaterials. Here, we demonstrate that locally ordered arrays of nanoparticles, using electrophoretic deposition, can be extended to produce long-range order among the constituents. Voronoi tessellations along with multiple statistical analyses show dramatic increases in order compared with previously reported assemblies formed through electric field-assisted assembly. Based on subsequent physical measurements of the nanoparticles and the deposition system, the underlying mechanisms that generate increased order are inferred. Ordered systems of nanoparticles (superlattices) have attracted interest in the research and industry due to their potential application in a wide variety of devices.1-4 Many emerging techniques have been proposed to fabricate these superlattices, including evaporative selfassembly, spin-casting, and ligand-mediated self-assembly, and more recently, electrophoretic deposition. [5][6][7][8] The eventual applicability of nanoparticle (NP) superlattices in a device depends on how well arranged (ordered, glassy, disordered, etc.) the constituent particles are, how cost-effective the process to produce the array is, and how dependent the proposed device applications are on the existing order. Comparably, just as macroscopic crystals behave differently from their amorphous counter parts, and the spectrum of atomic arrangement of amorphous to perfect crystalline has a continuum of properties, similar phenomena occur for supercrystals. 4 The degree of ordering of supercrystals can deeply affect the physical characteristics of the supercrystals and, thus, the applications in which they may be incorporated.Electrophoretic deposition (EPD) is an advantageous technique for the assembly of nanoparticles because of its ease of application, scalability, and rapid performance.10-16 A recently developed EPD technique has been able to create locally ordered monolayers of NPs. [16][17][18][19][20][21] Understanding the mechanisms that create the ordering could allow one to tune the ordering to create supercrystals using EPD. In this light, recently developed statistical measurement tools have been demonstrated to be effective in quantifying the degree of ordering within monolayers of nanoparticles. 19,20 Motivated by this work, this article explores the application of these tools to two different systems (iron oxide and cobalt ferrite nanoparticles) and the observation of markedly different degrees of order in the systems. Based on physical measurements of the NP systems, the mechanisms behind the ordering in each system are deduced. ExperimentalSuspension preparation and characterization.-Cobalt ferrite NPs were synthesized via a modified process of the thermal decom- * Electrochemical Society Active Member.z E-mail: jdickerson@bnl.gov position of Fe(acac) 3 and Co(acac) 2 in benzyl ether (BE), where acac is acetylacetonate. 22 A solution of Fe(acac) 3 (1.0 mmol), Co(acac) 2 (0.5 m...

Development of europium doped core-shell silica cobalt ferrite functionalized nanoparticles for magnetic resonance imaging

“…3C). These particle physicochemical characteristics are consistent with CF nanoparticles produced by other methods, suggesting that the solvothermal process used did not cause morphological changes to the nanoparticles [48–50]. To further characterize the synthesized magnetite particles, HR-TEM and SAED diffraction analysis was performed.…”

Development of Feasible and Economic Electrochemical Sensor Based on Manganese Ferrite Nanoparticles (Mn0.2Fe2.8O4) for Determination of a Platelet Aggregation Inhibitor Ticagrelor Drug in Formulations and Human Blood

“…31 Replacing Fe ions in interstitial sites with different metal ions such as Mn, Zn, Ga, Ni, Co or Cu will improve Fe 3 O 4 unique physical z E-mail: hanaa_eldesoky@Science.tanta.edu.eg; mhmubark@Science.tanta.edu.eg properties which originate from electrons hopping between Fe 2+ and Fe 3+ ions. [32][33][34][35][36] Xu et al, 25 reported that doping Mn Fe 3 O 4 NPs could provide a synergistic effect with Fe species for higher electrochemical reactivity.…”

0‐3 magnetic nanocomposites via EPD: Current status for power component fabrication and future directions

“…1-2 μm. [49][50][51][52][53][54] Recently, through several iterations and designs of experiments, new EPD parameters for successful iron oxide nanoparticle thick film fabrication (approximately 10 μm) were achieved. 29 Parameters such as particle concentration, molarity of the EPD bath solution, electrode-electrode distance, and deposition time were varied in order to obtain films that were sufficiently thick and crack free.…”

“…For 0‐3 magnetic nanocomposites for power component applications, there is a need for a robust, novel modification to the method in order to deposit magnetic nanoparticles via EPD into micron‐thick films. Previously, the EPD of magnetic oxide nanoparticles was not utilized to fabricate magnetic nanocomposites, due to a focus on monolayer film formation, and the fact that these were often not able to achieve film thicknesses above 1–2 μm 49–54 . Recently, through several iterations and designs of experiments, new EPD parameters for successful iron oxide nanoparticle thick film fabrication (approximately 10 μm) were achieved 29 …”