scholarly journals Influence of Magnetite Nanoparticles Shape and Spontaneous Surface Oxidation on the Electron Transport Mechanism

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5241
Author(s):  
Adrian Radoń ◽  
Mariola Kądziołka-Gaweł ◽  
Dariusz Łukowiec ◽  
Piotr Gębara ◽  
Katarzyna Cesarz-Andraczke ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Magnetite Nanoparticles ◽  
Average Particle Size ◽  
Electric Energy ◽  
Low Frequency ◽  
Surface Oxidation ◽  
Average Particle ◽  
Organic Modifiers ◽  
Magnetic And Electrical Properties

The spontaneous oxidation of a magnetite surface and shape design are major aspects of synthesizing various nanostructures with unique magnetic and electrical properties, catalytic activity, and biocompatibility. In this article, the roles of different organic modifiers on the shape and formation of an oxidized layer composed of maghemite were discussed and described in the context of magnetic and electrical properties. It was confirmed that Fe3O4 nanoparticles synthesized in the presence of triphenylphosphine could be characterized by cuboidal shape, a relatively low average particle size (9.6 ± 2.0 nm), and high saturation magnetization equal to 55.2 emu/g. Furthermore, it has been confirmed that low-frequency conductivity and dielectric properties are related to surface disordering and oxidation. The electric energy storage possibility increased for nanoparticles with a disordered and oxidized surface, whereas the dielectric losses in these particles were strongly related to their size. The cuboidal magnetite nanoparticles synthesized in the presence of triphenylphosphine had an ultrahigh electrical conductivity (1.02 × 10−4 S/cm at 10 Hz) in comparison to the spherical ones. At higher temperatures, the maghemite content altered the behavior of electrons. The electrical conductivity can be described by correlated barrier hopping or overlapping large polaron tunneling. Interestingly, the activation energies of electrons transport by the surface were similar for all the analyzed nanoparticles in low- and high-temperature ranges.

scholarly journals Effect of the polymeric coating over Fe3O4 particles used for magnetic separation

2010 ◽  
Vol 8 (5) ◽  
pp. 1041-1046 ◽  
Author(s):  
Raúl Reza ◽  
Carlos Martínez Pérez ◽  
Claudia Rodríguez González ◽  
Humberto Romero ◽  
Perla García Casillas
Keyword(s):  
Particle Size ◽  
Magnetite Nanoparticles ◽  
Average Particle Size ◽  
Spherical Shape ◽  
Polymeric Coating ◽  
Average Particle ◽  
Synthesis Conditions ◽  
Aging Conditions ◽  
Magnetite Particles ◽  
Average Size

AbstractIn this work, the synthesis of magnetite nanoparticles by two variant chemical coprecipitation methods that involve reflux and aging conditions was investigated. The influence of the synthesis conditions on particle size, morphology, magnetic properties and protein adsorption were studied. The synthesized magnetite nanoparticles showed a spherical shape with an average particle size directly influenced by the synthesis technique. Particles of average size 27 nm and 200 nm were obtained. When the coprecipitation method was used without reflux and aging, the smallest particles were obtained. Magnetite nanoparticles obtained from both methods exhibited a superparamagnetic behavior and their saturation magnetization was particle size dependent. Values of 67 and 78 emu g−1 were obtained for the 27 nm and 200 nm magnetite particles, respectively. The nanoparticles were coated with silica, aminosilane, and silica-aminosilane shell. The influence of the coating on protein absorption was studied using Bovine Serum Albumin (BSA) protein.

scholarly journals High Yield Synthesis and Application of Magnetite Nanoparticles (Fe3O4)

2020 ◽  
Vol 6 (2) ◽  
pp. 22 ◽  
Author(s):  
Charles Wroblewski ◽  
Tunde Volford ◽  
Blake Martos ◽  
Jurek Samoluk ◽  
Perry Martos
Keyword(s):  
Magnetite Nanoparticles ◽  
De Novo ◽  
Average Particle Size ◽  
Total Iron ◽  
High Yield ◽  
Chemical Compositions ◽  
Average Particle ◽  
Iron Salt ◽  
Mechanical Agitation ◽  
Aqueous Synthesis

Magnetite nanoparticles (Fe3O4), average particle size of 12.9 nm, were synthesized de novo from ferrous and ferric iron salt solutions (total iron salt concentration of 3.8 mM) using steady-state headspace NH3(g), 3.3% v/v, at room temperature and pressure, without mechanical agitation, resulting in >99.9% yield. Nanoparticles size distributions were based on enumeration of TEM images and chemical compositions analyzed by: XRD, EDXRF, and FT-IR; super-paramagnetic properties were analyzed by magnetization saturation (74 emu/g). Studies included varying headspace [NH3(g)] (1.6, 3.3, 8.4% v/v), and total iron concentrations (1.0 mM, 3.8 mM, 10.0 mM, and >>10 mM). An application of the unmodified synthesized magnetite nanoparticles included analyses of tetracycline’s (50, 100, 200, 300, and 400 ppb) in aqueous, which was compared to the same tetracycline concentrations prepared in aqueous synthesis suspension with >97% extraction, analyzed with LC-MS/MS.

FRACTAL GROWTH PATTERNS AND OSCILLATIONS IN POTENTIAL DURING ELECTROPOLYMERIZATION OF ANILINE WITH MONO- AND MIXED SURFACTANTS

Fractals ◽  
2011 ◽  
Vol 19 (03) ◽  
pp. 317-328 ◽  
Author(s):  
ISHWAR DAS ◽  
NAMITA R. AGRAWAL ◽  
RINKI CHOUDHARY ◽  
SANJEEV KUMAR GUPTA
Keyword(s):  
Electrical Conductivity ◽  
Average Particle Size ◽  
Sodium Dodecyl ◽  
Electrical Potential ◽  
Growth Patterns ◽  
Ammonium Bromide ◽  
Average Particle ◽  
Diffusion Limited Aggregation ◽  
Fractal Growth ◽  
Potential Oscillations

Fractal growth patterns of polyaniline were developed during electropolymerization of aniline using the surfactants sodium dodecyl sulphate (NaDS) and NaDS containing cetyl trimethyl ammonium bromide (CTAB). Growth kinetics was studied and electric potential oscillations were monitored as a function of time. On addition of CTAB polymer growth was inhibited due to coordination of CTAB with the growing polyaniline chain. The average particle size of the polymer aggregate obtained from aniline- NaDS-H2O system was ~150 nm as evident by Transmission Electron Microscopy (TEM) results. Polymer aggregates were characterized by electrical conductivity measurements, X-ray diffraction (XRD) and Thermogravimetric (TG) studies. An interaction between NaDS and aniline was observed in the absence of electric field as evident by (i) electrical conductivity of aqueous solution of NaDS in the absence and presence of aniline, and (ii) their crystallization patterns on microslides. A mechanism for the development of fractal patterns and electrical potential oscillations is proposed on the basis of diffusion limited aggregation process.

Evaluation of the Antimicrobial Activity of Citric Acid Functionalized Magnetite Nanoparticles

2020 ◽  
Vol EJMM29 (4) ◽  
pp. 143-149
Author(s):  
Ahmed M. El-Khawaga ◽  
Ayman A. Farrag ◽  
Ahmed I. El-Batal ◽  
Mohamed A. Elsayed
Keyword(s):  
Antimicrobial Activity ◽  
Citric Acid ◽  
Magnetite Nanoparticles ◽  
Pathogenic Bacteria ◽  
Average Particle Size ◽  
Maximum Activity ◽  
Precipitation Method ◽  
Average Particle ◽  
Effective Prevention ◽  
Fe3o4 Nps

Background: Antimicrobial resistance (AMR) has emerged as one of the principal public health problems of the 21st century that threatens the effective prevention and treatment of an ever-increasing range of infections caused by bacteria no longer susceptible to the common medicines used to treat them. Objectives: To development of Fe3O4 NPs with specific sizes and shapes Potential as a new antibacterial agent. Methodology: In this study magnetite nanoparticles (Fe3O4 NPs) were synthesized through an aqueous co-precipitation method and functionalized with citric acid for outstanding their antimicrobial potential. Fe3O4 NPs were characterized by XRD, TEM, SEM, EDX and FTIR to analyze crystallinity, average particle size, morphology and functional groups, respectively. Antimicrobial activity was investigated against pathogenic bacteria as zone of inhibition (ZOI) and minimum inhibitory concentration (MIC). Results: Antimicrobial results showed that CA- Fe3O4 NPs owns maximum activity against Staphylococcus aureus and E. coli by 18.0 and 15.0mm ZOI, respectively. Conclusion: It should be noted that (CA-Fe3O4) NPs are also active upon Gram-positive than Gram- negative bacteria. The synthesized (CA-Fe3O4) NPs are promising for potential applications as antimicrobial agent and in drug delivery fields.

Effect Of Surface Oxidation On Magnetic And Electrical Properties of nc-Ni Particles

2008 ◽  
Author(s):  
Soumen Kar ◽  
N. K. Kishore ◽  
V. Srinivas ◽  
Amitabha Ghoshray ◽  
Bilwadal Bandyopadhyay
Keyword(s):  
Electrical Properties ◽  
Surface Oxidation ◽  
Effect Of Surface ◽  
Magnetic And Electrical Properties

Electrical Properties of Silver Paste Prepared from Nanoparticles and Lead-Free Frit

2007 ◽  
Vol 7 (11) ◽  
pp. 3917-3919 ◽  
Author(s):  
Sung Hyun Park ◽  
Dong Seok Seo ◽  
Jong Kook Lee
Keyword(s):  
Silver Nanoparticles ◽  
Electrical Properties ◽  
Screen Printing ◽  
Chemical Reduction ◽  
Silver Powder ◽  
Average Particle Size ◽  
Average Particle ◽  
Chemical Reduction Method ◽  
Silver Paste ◽  
Thermal And Electrical Properties

Recently, PbO containing glass systems in commercial silver paste have been used due to their low glass transition temperature, good thermal and electrical properties. However, PbO is a hazardous material to both health and the environment. In this study, Pb-free silver paste was prepared by mixing commercial silver powder and silver nanoparticles. The commercial powder has an average particle size of 1.6 μm. The silver nanoparticles with particles size of 20–50 nm were synthesized by a chemical reduction method using surfactant. Pb-free frit was added into the mixed silver powder as the amounts of 3, 6 and 9 wt%. Using the obtained paste, thick films were fabricated by a screen printing on alumina substrate and the films were fired at temperature from 400 to 550 °C. The films had thickness of 6–11 μm and sheet resistivity of about 4–11 μΩ cm.

Preparation and Sintering Behavior of Au Conductor Pastes for LTCC Substrate

2005 ◽  
Vol 475-479 ◽  
pp. 1763-1766 ◽  
Author(s):  
Yan Wang ◽  
Yang Liu ◽  
Ju Sheng Ma ◽  
Zhaowen Dong ◽  
Mingli Yin
Keyword(s):  
Electrical Conductivity ◽  
Particle Size ◽  
Design Method ◽  
Orthogonal Design ◽  
Average Particle Size ◽  
Sintering Behavior ◽  
Average Particle ◽  
High Electrical Conductivity ◽  
Orthogonal Design Method ◽  
Ltcc Substrate

Fine Au powders with spherical morphology and good dispersivity were produced. The average particle size is 1~2m. The influences of constituents on the rheology of organic vehicles were investigated by orthogonal design method. Consequently, the compatible Au thick film pastes for LTCC substrate have been prepared. SEM was carried out to study the sintering behaviors and microstructures of the buried pastes with LTCC substrate. These pastes have high electrical conductivity (less than 3m/sq.), reliable wire bond strength (greater than 9 grams, 25m Au wire) and fine line printability (as small as 80m). The via filling technology was also discussed in this paper.

scholarly journals Reversible redox switching of magnetic order and electrical conductivity in a 2D manganese benzoquinoid framework

2020 ◽  
Author(s):  
Lujia Liu
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Single Crystal ◽  
Magnetic Order ◽  
Magnetic Measurements ◽  
Fold Increase ◽  
Parent Material ◽  
Formidable Challenge ◽  
Redox Switching ◽  
Magnetic And Electrical Properties

© 2019 The Royal Society of Chemistry. Materials with switchable magnetic and electrical properties may enable future spintronic technologies, and thus hold the potential to revolutionize how information is processed and stored. While reversible switching of magnetic order or electrical conductivity has been independently realized in materials, the ability to simultaneously switch both properties in a single material presents a formidable challenge. Here, we report the 2D manganese benzoquinoid framework (Me4N)2[MnII2(L2-)3] (H2L = 2,5-dichloro-3,6-dihydroxo-1,4-benzoquinone), as synthesized via post-synthetic counterion exchange. This material is paramagnetic above 1.8 K and exhibits an ambient-temperature electrical conductivity of σ295 K = 1.14(3) × 10-13 S cm-1 (Ea = 0.74(3) eV). Upon soaking in a solution of sodium naphthalenide and 1,2-dihydroacenaphthylene, this compound undergoes a single-crystal-to-single-crystal (SC-SC) reduction to give Na3(Me4N)2[Mn2L3]. Structural and spectroscopic analyses confirm this reduction to be ligand-based, and as such the anionic framework is formulated as [MnII2(L3-)3]5-. Magnetic measurements confirm that this reduced material is a permanent magnet below Tc = 41 K and exhibits a conductivity value of σ295 K = 2.27(1) × 10-8 S cm-1 (Ea = 0.489(8) eV), representing a remarkable 200 000-fold increase over the parent material. Finally, soaking the reduced compound in a solution of [Cp2Fe]+ affords Na(Me4N)[MnII2(L2-)3] via a SC-SC process, with magnetic and electrical properties similar to those observed for the original oxidized material. Taken together, these results highlight the ability of metal benzoquinoid frameworks to undergo reversible, simultaneous redox switching of magnetic order and electrical conductivity.

Effect of Alumina Additions on Mechanical and Electrical Properties of 8mol% Yttria-Stabilized Zirconia Prepared by Spark Plasma Sintering

2006 ◽  
Vol 317-318 ◽  
pp. 917-920
Author(s):  
Jae Kwang Kim ◽  
Kyung Hun Kim ◽  
Yong Ho Choa ◽  
Jong Won Yoon ◽  
Kwang Bo Shim
Keyword(s):  
Electrical Conductivity ◽  
Grain Size ◽  
Relative Density ◽  
Spark Plasma Sintering ◽  
Average Particle Size ◽  
Yttria Stabilized Zirconia ◽  
Average Particle ◽  
Stabilized Zirconia ◽  
Plasma Sintering ◽  
Spark Plasma

Dense 8mol% yttria-stabilized zirconia (8YSZ) consisting of submicrometer-sized grains was prepared using spark plasma sintering (SPS) along with Al2O3 additives. The starting powder with average particle size of 50nm was densified to 98% of the relative density with short sintering time (5min) at 1200 while preserving a submicrometer grain size. The fracture toughness and bending strength showed maximum values of 2.54MPam1/2 and 380MPa at 2vol% alumina-added 8YSZ, due mainly to the higher relative density and small grain size. The electrical conductivity of 2vol% alumina-added 8YSZ was 0.0278 S/cm at 700 in airThus, alumina additions in 8YSZ using the SPS method are an effective process to improve the mechanical strength and electrical conductivity.

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