Study of the growth process of magnetic nanoparticles obtained via the non-aqueous sol–gel method

Masthoff, I.-C.; Kraken, M.; Mauch, Daniel; Menzel, D.; Munévar, J.; Baggio-Saitovitch, E.; Litterst, F. J.; Garnweitner, Georg

doi:10.1007/s10853-014-8160-0

Cited by 35 publications

(20 citation statements)

References 30 publications

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“…In the thermal decomposition route, such partial reduction of Fe 3+ to Fe 2+ is favored by the presence of the mild‐reducing agent 1,2‐hexadecanediol . On the contrary, we can associate the slight Co deficiency in SV NPs to the presence of a small number of vacancies because the solvothermal route lacks of reducing conditions …”

Section: Resultsmentioning

confidence: 95%

Internal Structure and Magnetic Properties in Cobalt Ferrite Nanoparticles: Influence of the Synthesis Method

Lavorato

Alzamora

Contreras

et al. 2019

Part & Part Syst Charact

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The design of novel nanostructured magnetic materials requires a good understanding of the variation in the magnetic properties due to different synthesis conditions. In this work, four different procedures for fabricating Co‐ferrite nanoparticles with similar sizes between 7 and 10 nm are compared by studying their structural and magnetic properties. Non‐aqueous methods based on the thermal decomposition of metal acetylacetonates at high temperatures, either with or without surfactants, provide highly crystalline nanoparticles with large saturation magnetization values and a coherent reversal of the magnetic moment. However, variations in the density of defects and in the shape of the nanocrystals determine the distribution of switching fields and the effective magnetic anisotropy, which reaches up to ≈1 × 107 erg cm−3 for oleic acid‐capped 9 nm nanoparticles. It is shown that the saturation magnetization values for nanoparticles produced by different methods are in the range between 49 and 95 emu g−1 due to differences in the stoichiometry, in the cation occupancy, in the magnetic disorder and in the spin canting of the magnetic sub‐lattices, the latter evaluated by in‐field Mössbauer spectroscopy.

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Section: Resultsmentioning

confidence: 95%

Internal Structure and Magnetic Properties in Cobalt Ferrite Nanoparticles: Influence of the Synthesis Method

Lavorato

Alzamora

Contreras

et al. 2019

Part & Part Syst Charact

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“…29,30 Detailed investigations have revealed that the iron oxide particles under the used conditions typically form as mixed magnetite–maghemite nanocrystals both in hydrophobic and hydrophilic organic reaction media. 31,32…”

Section: Results and Discussionmentioning

confidence: 99%

Spray-Dried Hierarchical Aggregates of Iron Oxide Nanoparticles and Their Functionalization for Downstream Processing in Biotechnology

et al. 2019

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In this work, the structuring of iron oxide nanoparticles via spray-drying (SD) of aqueous suspensions is investigated, leading to micrometer-sized aggregates with saturation magnetization comparable to that of the individual nanoparticles. Interestingly, the superparamagnetic behavior is retained despite the multicore structure. Modification of the aggregates via the addition of silica nanoparticles to the suspension allows for control of the resulting magnetization by adjusting the iron oxide content. Moreover, the morphology of the produced aggregates is gradually shifted from irregular inflated-like shapes in case of pure iron oxide aggregates to reach spherical structures when bringing the silica content to only 20%. The aggregates with different magnetization can be effectively separated in a simple column with an attached permanent magnet. Functionalization of pure iron oxide aggregates with a previously coupled ligand holding a nitrilotriacetic acid (NTA)-like moiety and subsequent loading with Ni2+ ions leads to the ability to bind 6-histidine (His6)-tagged target proteins via chelation complexes for magnetic separation. The application of the presented system for the purification of recombinant protein A in multiple cycles is shown. The recyclability of the separation system in combination with the high degree of magnetic separation is promising for future applications in the field of preparative in situ protein purification.

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“…Therefore, it was easily possible to obtain particles with ac ertain size, crystallinity and thusc ustomized magnetic properties. [254] Af ollow-up study of the growth of iron oxide nanoparticles in TEG confirmed that in af irst step an amorphous network was formed, which, upon expulsion of organic compounds,s lowly crystallized and grew into hydrophilic iron oxide nanoparticles of about 8nmi nd iameter. [255] Accordingly,particle formation in benzyl alcoholf ollowed ac lassical nucleation and growth model, while in TEG as ol-gel reaction with an intermediate gel-like network occurred.…”

Section: Crystallization Mechanismsmentioning

confidence: 89%

“…Indeed, the authors found a direct correlation of the crystallinity of the nanoparticles with their magnetic properties. Therefore, it was easily possible to obtain particles with a certain size, crystallinity and thus customized magnetic properties . A follow‐up study of the growth of iron oxide nanoparticles in TEG confirmed that in a first step an amorphous network was formed, which, upon expulsion of organic compounds, slowly crystallized and grew into hydrophilic iron oxide nanoparticles of about 8 nm in diameter .…”

Section: Crystallization Mechanismsmentioning

confidence: 95%

Mechanistic Aspects in the Formation, Growth and Surface Functionalization of Metal Oxide Nanoparticles in Organic Solvents

Deshmukh

Niederberger

2017

Chemistry A European J

106

112

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The synthesis of metal oxide nanoparticles in organic solvents, so-called nonaqueous (or nonhydrolytic) processes represent powerful alternatives to aqueous approaches and have become an independent research field. 10 Years ago, when we published our first review on organic reaction pathways in nonaqueous sol-gel approaches, the number of examples was relatively limited. Nowadays, it is almost impossible to provide an exhaustive overview. Here we review the development of the last few years, without neglecting pioneering examples, which help to follow the historical development. The importance of a profound understanding of mechanistic aspects of nanoparticle crystallization and formation mechanisms can't be overestimated, when it comes to the design of rational synthesis concepts under minimization of trial-and-error experiments. The main reason for the progress in mechanistic understanding lies in the availability of characterization tools that make it possible to monitor chemical reactions from the dissolution of the precursor to the nucleation and growth of the nanoparticles, by ex situ methods involving sampling after different reaction times, but more and more also by in situ studies. After a short introduction to experimental aspects of nonaqueous sol-gel routes to metal oxide nanoparticles, we provide an overview of the main and basic organic reaction pathways in these approaches. Afterwards, we summarize the main characterization methods to study formation mechanisms, and then we discuss in great depth the chemical formation mechanisms of many different types of metal oxide nanoparticles. The review concludes with a paragraph on selected crystallization mechanisms reported for nonaqueous systems and a few illustrative examples of nonaqueous sol-gel concepts applied to surface chemistry.

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Study of the growth process of magnetic nanoparticles obtained via the non-aqueous sol–gel method

Cited by 35 publications

References 30 publications

Internal Structure and Magnetic Properties in Cobalt Ferrite Nanoparticles: Influence of the Synthesis Method

Internal Structure and Magnetic Properties in Cobalt Ferrite Nanoparticles: Influence of the Synthesis Method

Spray-Dried Hierarchical Aggregates of Iron Oxide Nanoparticles and Their Functionalization for Downstream Processing in Biotechnology

Mechanistic Aspects in the Formation, Growth and Surface Functionalization of Metal Oxide Nanoparticles in Organic Solvents

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