scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Effect of initial pH and temperature of iron salt solutions on formation of magnetite nanoparticles

15 May 2007-Materials Chemistry and Physics (Elsevier)-Vol. 103, Iss: 1, pp 168-175
TL;DR: In this paper, the effect of initial pH and temperature of iron salt solutions on formation of magnetite (Fe3O4) nanoparticles during co-precipitation was reported.
About: This article is published in Materials Chemistry and Physics.The article was published on 2007-05-15. It has received 287 citations till now. The article focuses on the topics: Magnetite & Ferric.
Citations
More filters
Journal ArticleDOI
TL;DR: Nanoparticles with cores composed of inorganic materials such as noble, magnetic metals, their alloys and oxides, and semiconductors have been most studied and have vast potential for application in many different areas of biomedicine.

598 citations

Journal ArticleDOI
TL;DR: In this article, the size of the magnetite nanoparticles was carefully controlled by varying the reaction temperature and through surface modification, which significantly affected the particle size, the electrical conductivity, and the magnetic properties.
Abstract: Magnetite nanoparticles were synthesized via the chemical co-precipitation method using ammonium hydroxide as the precipitating agent. The size of the magnetite nanoparticles was carefully controlled by varying the reaction temperature and through the surface modification. Herein, the hexanoic acid and oleic acid were introduced as the coating agents during the initial crystallization phase of the magnetite. Their structure and morphology were characterized by the Fourier transform infrared spectroscopy (FTIR), the X-ray diffraction (XRD) and the field-emission scanning electron microscopy (FE-SEM). Moreover, the electrical and magnetic properties were studied by using a conductivity meter and a vibrating sample magnetometer (VSM), respectively. Both of the bare magnetite and the coated magnetite were of the cubic spinel structure and the spherical-shaped morphology. The reaction temperature and the surface modification critically affected the particle size, the electrical conductivity, and the magnetic properties of these particles. The particle size of the magnetite was increased through the surface modification and reaction temperature. In this study, the particle size of the magnetite nanoparticles was successfully controlled to be in the range of 10–40 nm, suitable for various biomedical applications. The electrical conductivity of the smallest particle size was 1.3 × 10−3 S/cm, within the semi-conductive materials range, which was higher than that of the largest particle by about 5 times. All of the magnetite nanoparticles showed the superparamagnetic behavior with high saturation magnetization. Furthermore, the highest magnetization was 58.72 emu/g obtained from the hexanoic acid coated magnetite nanoparticles.

589 citations

Journal ArticleDOI
TL;DR: Fe3O4 nanoparticles are promising potential adsorbents and exhibited remarkable reusability for metal ions removal in water and wastewater treatment.

527 citations

Journal ArticleDOI
TL;DR: Magnetite nanoparticles (Fe3O4) represent the most promising materials in medical applications and are incorporated into mesoporous materials to form a hybrid support with the consequent reduction of magnetization saturation to favor high-drug or enzyme loading.
Abstract: Magnetite nanoparticles (Fe₃O₄) represent the most promising materials in medical applications. To favor high-drug or enzyme loading on the nanoparticles, they are incorporated into mesoporous materials to form a hybrid support with the consequent reduction of magnetization saturation. The direct synthesis of mesoporous structures appears to be of interest. To this end, magnetite nanoparticles have been synthesized using a one pot co-precipitation reaction at room temperature in the presence of different bases, such as NaOH, KOH or (C₂H₅)₄NOH. Magnetite shows characteristics of superparamagnetism at room temperature and a saturation magnetization (Ms) value depending on both the crystal size and the degree of agglomeration of individual nanoparticles. Such agglomeration appears to be responsible for the formation of mesoporous structures, which are affected by the pH, the nature of alkali, the slow or fast addition of alkaline solution and the drying modality of synthesized powders.

465 citations


Cites background from "Effect of initial pH and temperatur..."

  • ...This effect has been reported, in great number, previously [26,28,29,31]....

    [...]

  • ...rate [27], digestion time [28], initial pH [29] and the presence or absence of a magnetic field [19,30] on particle size, morphology and resulting magnetic properties were also discussed....

    [...]

Journal ArticleDOI
TL;DR: The preparation of nanofluids by various techniques, methods of stabilization, stability measurement techniques, thermal conductivity and heat capacity studies, proposed mechanisms of heat transport, theoretical models on thermal Conductivity, factors influencing k and the effect of nanoinclusions in PCM are discussed in this review.

341 citations


Additional excerpts

  • ...Our studies on model soft micellar system of average size 2.5 to 7 nm with different head group charges show that the thermal conductivity of surfactant micelles follows EMT of poor thermal conductors....

    [...]

  • ...The observed k enhancement was above the EMT prediction....

    [...]

  • ...Recent studies shows that the stable nanofluids exhibits thermal conductivity within EMT prediction whereas aggregating nanofluids shows enhancement beyond EMT predictions....

    [...]

  • ...The EMT fit is shown in Fig.18 by a solid line....

    [...]

  • ...5.0 Theoretical Studies on Thermal Conductivity of Nanofluids Maxwell 183 derived an expression for the thermal conductivity of composite mixtures using Effective Medium Theory (EMT) by considering a spatially homogeneous electromagnetic AC C EP TE D M AN U SC R IP T response....

    [...]

References
More filters
Book
01 Jun 1972
TL;DR: In this paper, the authors present materials at the practical rather than theoretical level, allowing for a physical, quantitative, measurement-based understanding of magnetism among readers, be they professional engineers or graduate-level students.
Abstract: Introduction to Magnetic Materials, 2nd Edition covers the basics of magnetic quantities, magnetic devices, and materials used in practice. While retaining much of the original, this revision now covers SQUID and alternating gradient magnetometers, magnetic force microscope, Kerr effect, amorphous alloys, rare-earth magnets, SI Units alongside cgs units, and other up-to-date topics. In addition, the authors have added an entirely new chapter on information materials. The text presents materials at the practical rather than theoretical level, allowing for a physical, quantitative, measurement-based understanding of magnetism among readers, be they professional engineers or graduate-level students.

6,573 citations


"Effect of initial pH and temperatur..." refers background in this paper

  • ...The reported saturation magnetization values for magnetite and maghemite are about 90 and 80, respectively [37]....

    [...]

  • ...In maghemite, unequal distribution of Fe3+ ions in tetrahedral and octahedral sites leads to a net magnetization [37]....

    [...]

Journal ArticleDOI
TL;DR: This work is able to synthesize as much as 40 g of monodisperse nanocrystals in a single reaction, without a size-sorting process, and the particle size could be controlled simply by varying the experimental conditions.
Abstract: The development of nanocrystals has been intensively pursued, not only for their fundamental scientific interest, but also for many technological applications. The synthesis of monodisperse nanocrystals (size variation <5%) is of key importance, because the properties of these nanocrystals depend strongly on their dimensions. For example, the colour sharpness of semiconductor nanocrystal-based optical devices is strongly dependent on the uniformity of the nanocrystals, and monodisperse magnetic nanocrystals are critical for the next-generation multi-terabit magnetic storage media. For these monodisperse nanocrystals to be used, an economical mass-production method needs to be developed. Unfortunately, however, in most syntheses reported so far, only sub-gram quantities of monodisperse nanocrystals were produced. Uniform-sized nanocrystals of CdSe (refs 10,11) and Au (refs 12,13) have been produced using colloidal chemical synthetic procedures. In addition, monodisperse magnetic nanocrystals such as Fe (refs 14,15), Co (refs 16-18), gamma-Fe(2)O(3) (refs 19,20), and Fe(3)O(4) (refs 21,22) have been synthesized by using various synthetic methods. Here, we report on the ultra-large-scale synthesis of monodisperse nanocrystals using inexpensive and non-toxic metal salts as reactants. We were able to synthesize as much as 40 g of monodisperse nanocrystals in a single reaction, without a size-sorting process. Moreover, the particle size could be controlled simply by varying the experimental conditions. The current synthetic procedure is very general and nanocrystals of many transition metal oxides were successfully synthesized using a very similar procedure.

3,704 citations

Journal ArticleDOI
Shouheng Sun1, Hao Zeng1, David B. Robinson1, Simone Raoux1, Philip M. Rice1, Shan X. Wang1, Guanxiong Li1 
TL;DR: As-synthesized iron oxide nanoparticles have a cubic spinel structure as characterized by HRTEM, SAED, and XRD and can be transformed into hydrophilic ones by adding bipolar surfactants, and aqueous nanoparticle dispersion is readily made.
Abstract: High-temperature solution phase reaction of iron(III) acetylacetonate, Fe(acac)3, with 1,2-hexadecanediol in the presence of oleic acid and oleylamine leads to monodisperse magnetite (Fe3O4) nanoparticles. Similarly, reaction of Fe(acac)3 and Co(acac)2 or Mn(acac)2 with the same diol results in monodisperse CoFe2O4 or MnFe2O4 nanoparticles. Particle diameter can be tuned from 3 to 20 nm by varying reaction conditions or by seed-mediated growth. The as-synthesized iron oxide nanoparticles have a cubic spinel structure as characterized by HRTEM, SAED, and XRD. Further, Fe3O4 can be oxidized to Fe2O3, as evidenced by XRD, NEXAFS spectroscopy, and SQUID magnetometry. The hydrophobic nanoparticles can be transformed into hydrophilic ones by adding bipolar surfactants, and aqueous nanoparticle dispersion is readily made. These iron oxide nanoparticles and their dispersions in various media have great potential in magnetic nanodevice and biomagnetic applications.

3,244 citations

PatentDOI
04 Jun 2001-Science
TL;DR: A method of constructing <30-nanometer structures in close proximity with precise spacings is presented that uses the step-by-step application of organic molecules and metal ions as size-controlled resists on predetermined patterns, such as those formed by electron-beam lithography.
Abstract: The present invention is a method and apparatus relating to manufacturing nanostructure patterns and components using molecular science. The method includes overlaying a multilayer organic molecule resist on at least a portion of a parent structure selectively deposited on a substrate, depositing a layer over the parent structure and in contact with at least a portion of the multilayer organic resist, and removing the multilayer organic molecule resist to leave a residual structure.

2,301 citations