In situ synthesis of lithium ferrite nanoparticle/polymer hybrid

2007 ◽  
Vol 22 (4) ◽  
pp. 974-981 ◽  
Author(s):  
Koichiro Hayashi ◽  
Wataru Sakamoto ◽  
Toshinobu Yogo
Keyword(s):  
Spinel Ferrite ◽  
Organic Matrix ◽  
Blocking Temperature ◽  
Lithium Ferrite ◽  
Zero Field ◽  
Organic Hybrid ◽  
Ferrite Particle ◽  
Ferrite Nanoparticle ◽  
Hydrolysis Conditions

Lithium ferrite particle/organic hybrid was synthesized in situ from iron–organic and lithium–organic compounds below 100 °C. Spinel ferrite particle/organic hybrid was synthesized by hydrolyzing a mixture of iron (III) 3-allylacetylacetonate (IAA) and lithium acrylate (LA). X-ray diffraction analysis revealed that the crystallinity of spinel particle was dependent on the polymerization treatment and the hydrolysis conditions. The saturation magnetization of hybrid increased with increasing methylhydrazine and water amount of hydrolysis. Nanocrystalline lithium ferrite particle about 5 nm was dispersed in the organic matrix. The hybrid showed neither remanence nor coercive force at room temperature. The magnetization versus field/temperature H/T curves from 100 to 300 K were superimposed on the same curve and satisfied the Langevin equation. The zero-field-cooled (ZFC) and field-cooled (FC) magnetization curve revealed that the blocking temperature was about 75 K. The remanent magnetization and coercive field of the hybrid were 8.9 A·m2/kg and 26.3 kA/m, respectively, at 10 K.

In situ Synthesis of Nickel Ferrite Nanoparticle/organic Hybrid

2005 ◽  
Vol 20 (6) ◽  
pp. 1590-1596 ◽  
Author(s):  
Satoshi Nakamura ◽  
Wataru Sakamoto ◽  
Toshinobu Yogo
Keyword(s):  
Photoelectron Spectroscopy ◽  
Nickel Ferrite ◽  
Oxide Particle ◽  
Organic Matrix ◽  
X Ray ◽  
Organic Hybrid ◽  
Ferrite Particle ◽  
Ferrite Nanoparticle ◽  
Hydrolysis Conditions

A NiFe2O4 particle/organic hybrid was synthesized in situ from iron-organic and nickel organic compounds below 100 °C. A mixture of nickel (II) acetylacetonate (NA) and iron (III) 3-allylacetylacetonate (IAA) was hydrolyzed and polymerized yielding spinel oxide particle/oligomer hybrid. X-ray diffraction analysis revealed that the crystallinity of spinel particles was dependent upon the hydrolysis conditions of NA-IAA. Nanocrystalline nickel ferrite particles around 10 nm were uniformly dispersed in the organic matrix. The formation of nickel ferrite was confirmed by energy-dispersive x-ray and x-ray photoelectron spectroscopy. The saturation magnetization of hybrid increased with increasing water amount for hydrolysis. Nano-sized nickel ferrite particle/organic hybrid showed a BH curve with no remanence above 75 K. The magnetization versus H/T curves at 300, 200, and 75 K were superimposed on the same curve and satisfied the Langevin equation. The remanent magnetization and coercive field of the hybrid were 7.4 emu/g and 460 Oe, respectively, at 5 K.

Synthesis of nickel zinc ferrite nanoparticle/organic hybrid from metalorganics

2007 ◽  
Vol 22 (7) ◽  
pp. 1967-1974 ◽  
Author(s):  
Yasuaki Hayashimto ◽  
Wataru Sakamoto ◽  
Toshinobu Yogo
Keyword(s):  
Zinc Ferrite ◽  
Oxide Particle ◽  
Organic Matrix ◽  
X Ray Diffraction ◽  
Organic Hybrid ◽  
Nickel Zinc ◽  
Ferrite Particle ◽  
Ferrite Nanoparticle ◽  
Hydrolysis Conditions

(Ni,Zn)Fe2O4 particle/organic hybrid was synthesized in situ from metalorganics below 100 °C. A mixture of nickel (II) acetylacetonate (NA), zinc acetylacetonate (ZA), and iron (III) 3-allylacetylacetonate (IAA) was hydrolyzed and polymerized yielding a spinel oxide particle/organic hybrid. X-ray diffraction analysis revealed that the crystallinity of spinel particles was dependent upon the hydrolysis conditions of NA-ZA-IAA. Nanocrystalline nickel zinc ferrite particles below 5 nm were uniformly dispersed in the organic matrix. The magnetization of hybrid increased with an increasing amount of water for hydrolysis. Nano-sized nickel zinc ferrite particle/organic hybrid showed a magnetization-applied field (BH) curve with no remanence above 40 K. The magnetization versus H/T curves from 40 to 100 K were superimposed on the same curve and satisfied the Langevin equation. The remanent magnetization and coercive field of the hybrid were 7.2 emu/g and 150 Oe, respectively, at 4.2 K. The absorption edge of the hybrid was blue-shifted compared with that of bulk ferrite.

In situ synthesis of nano-sized cobalt ferrite particle/organic hybrid

2006 ◽  
Vol 21 (5) ◽  
pp. 1336-1341 ◽  
Author(s):  
Satoshi Nakamura ◽  
Wataru Sakamoto ◽  
Toshinobu Yogo
Keyword(s):  
Saturation Magnetization ◽  
Room Temperature ◽  
Cobalt Ferrite ◽  
Organic Matrix ◽  
In Situ Synthesis ◽  
Organic Hybrid ◽  
Ferrite Particle ◽  
Hydrolysis Conditions ◽  
Cobalt Acetylacetonate

A CoFe2O4 particle/organic hybrid was synthesized using in situ processing of metalorganics of cobalt and iron below 100 °C. A mixture of cobalt (II) acetylacetonate (CA) and iron (III) 3-allylacetylacetonate (IAA) was hydrolyzed and polymerized yielding cobalt ferrite particle/organic hybrid. The crystallinity of cobalt ferrite depended upon the hydrolysis conditions of cobalt acetylacetonate-iron 3-allylacetylacetonate (CA-IAA). Nanocrystalline cobalt ferrite particles were uniformly dispersed in the organic matrix. The saturation magnetization of hybrid increased with increasing crystallinity of cobalt ferrite particles in the organic matrix. The hybrid showed a magnetization-applied field (BH) curve with no coercive force at room temperature. The magnetization versus H/T curves from 150 to 300 K were superimposed on the same curve and satisfied the Langevin equation. The hybrid revealed a saturation magnetization of 33.7 emu/g and a coercivity of 11 kOe at 4.2 K.

Synthesis of spinel iron oxide nanoparticle/organic hybrid for hyperthermia

2008 ◽  
Vol 23 (12) ◽  
pp. 3415-3424 ◽  
Author(s):  
Koichiro Hayashi ◽  
Toshifumi Shimizu ◽  
Hidefumi Asano ◽  
Wataru Sakamoto ◽  
Toshinobu Yogo
Keyword(s):  
Magnetic Field ◽  
Iron Oxide ◽  
Photoelectron Spectroscopy ◽  
Iron Oxide Nanoparticle ◽  
Organic Hybrid ◽  
Oxide Nanoparticle ◽  
Hydrolysis Conditions ◽  
Size Controlled ◽  
Controlled Hydrolysis

Size-controlled spinel iron oxide (SIO) nanoparticle/organic hybrid was synthesized in situ from iron (III) allylacetylacetonate (IAA) at around 80 °C. The formation of SIO particles chemically bound with organics was confirmed by infrared and x-ray photoelectron spectroscopy. The sizes of SIO nanoparticles in the hybrids were monodispersed and ranged from 7 to 23 nm under controlled hydrolysis conditions. The hybrid including SIO particles of 7.3 nm was superparamagnetic, whereas those dispersed with particles above 11 nm were ferrimagnetic. The specific absorption rate (SAR) value was dependent upon the magnetic properties of the hybrid at 100 Oe. The SAR was 15.2 W g−1 in a 230 kHz alternating magnetic field and 100 Oe when the crystallite size of SIO particle in the hybrid was 16 nm. The temperatures of agars dispersed with hybrid powders of 5 and 8 mg ml−1 reached the optimum temperature (42 °C) for 17 and 8 min, respectively. The increase in temperature was controlled in terms of the strength of magnetic field. The simulation of heat transfer in the agar phantom model revealed that the suitable temperature distribution for therapy was attained from 15 to 20 min at 230 kHz and 100 Oe.

Synthesis of transparent magnetic particle/organic hybrid film using iron–organics

2000 ◽  
Vol 15 (10) ◽  
pp. 2114-2120 ◽  
Author(s):  
Toshinobu Yogo ◽  
Tomoyuki Nakamura ◽  
Wataru Sakamoto ◽  
Shin-ichi Hirano
Keyword(s):  
Iron Oxide ◽  
Magnetization Curve ◽  
Magnetic Particles ◽  
Magnetic Particle ◽  
Hybrid Film ◽  
Oxide Particle ◽  
Iron Oxide Particle ◽  
Organic Hybrid ◽  
Hydrolysis Conditions

A transparent magnetic particle/organic film was synthesized from an iron–organic compound. Iron(III) 3-allylacetylacetonate (IAA) was polymerized followed by in situ hydrolysis yielding an iron oxide particle/oligomer hybrid. The sizes of magnetic particles were dependent upon the hydrolysis conditions of the IAA oligomers. A nanometer-sized ferrimagnetic iron oxide particle/oligomer hybrid showed a magnetization curve with no coercive force at 300 K and that with Hc of 200 Oe at 4.2 K, respectively. The magnetization versus H/T curves at 300 and 77 K were superimposed on each other and satisfied the Langevin equation. The transparent hybrid film showed a magnetization curve at room temperature. The absorption spectrum of the film was shifted to higher energy by 0.14 eV compared with that of bulk magnetite. The absorption edge of the film was blue-shifted.

Synthesis of PbTiO3/organic hybrid from metalorganic compounds

1999 ◽  
Vol 14 (8) ◽  
pp. 3275-3280 ◽  
Author(s):  
Toshinobu Yogo ◽  
Hiroyuki Ukai ◽  
Wataru Sakamoto ◽  
Shin-ichi Hirano
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Lead Titanate ◽  
Organic Matrix ◽  
Titanium Isopropoxide ◽  
Resonance Spectroscopy ◽  
X Ray ◽  
Organic Hybrid ◽  
Nanocrystalline Particles ◽  
Hydrolysis Conditions ◽  
Metalorganic Compounds

A nanocrystalline PbTiO3 particle/organic hybrid was synthesized through hydrolysis and polymerization of metalorganic compounds below 100 °C. The PbTiO3 precursor was synthesized from lead methacrylate and titanium isopropoxide. The formation of a Pb–Ti complex alkoxide was confirmed by H and Pb nuclear magnetic resonance spectroscopy. Hydrolyzed Pb–Ti alkoxide was polymerized, yielding the PbTiO3 particles/oligomer hybrid. The organic matrix included nano-sized crystalline particles, depending on the hydrolysis conditions. The nanocrystalline particles were identified to be lead titanate by electron diffraction and energy-dispersive x-ray analysis. The dielectric constant of the nanometer-sized PbTiO3/oligomer hybrid was 5.2 at 10 kHz.

In situ fabrication of metal–organic hybrid gels in a capillary for online enrichment of trace analytes in aqueous samples

2012 ◽  
Vol 48 (33) ◽  
pp. 3966 ◽  
Author(s):  
Yuling Hu ◽  
Yifeng Fan ◽  
Zelin Huang ◽  
Chaoyong Song ◽  
Gongke Li
Keyword(s):  
Aqueous Samples ◽  
Hybrid Gels ◽  
Organic Hybrid ◽  
In Situ Fabrication ◽  
Metal Organic

Stm Studies at Electrochemically Controlled Interfaces

1994 ◽  
Vol 332 ◽  
Author(s):  
S.M. Lindsay ◽  
J. Pan ◽  
T.W. Jing
Keyword(s):  
Electron Tunneling ◽  
Point Contact ◽  
Localized States ◽  
Scanning Tunneling ◽  
Zero Field ◽  
Tunneling Microscopy ◽  
Dna Oligomers ◽  
Synthetic Dna ◽  
Quantum Point

ABSTRACTWe use electrochemical methods to control the adsorption of molecules onto an electrode for imaging in-situ by scanning tunneling microscopy. Measurements of the barrier for electron tunneling show that the mechanism of electron transfer differs from vacuum tunneling. Barriers depend upon the direction of electron tunneling, indicating the presence of permanently aligned dipoles in the tunnel gap. We attribute a sharp dip in the barrier near zero field to induced polarization. We propose a ‘tunneling’ process consisting of two parts: One is delocalization of quantum-coherent states in parts of the molecular adlayer that hybridize strongly (interaction ≥ kT) with Bloch states in the metal. This gives rise to a quantum-point-contact conductance, Gc ≤ 2e2/h at a height zo. The other part comes from the exponential decay of the tails of localized states, G = Gc exp{−2K(z − z0)}. Because measured decay lengths, (2K‘)−1, are small (≈ 1 Å), STM contrast is dominated by the contour along which G[z0 (x,y)] = Gc. Measured changes in z0 are used to calculate images which are in reasonable agreement with observations. We illustrate this with images of synthetic DNA oligomers.

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