135 research outputs found
Magnetoresistance at Room Temperature of Oleic Acid Coated Fe3-xCoxO4 (x = 0, 0.1 and 0.3) Nanocrystal Drop-Cast Films
Oleic acid coated Fe3-xCoxO4 (x = 0, 0.1 and 0.3) nanocrystal self-assembled films were fabricated via drop-casting of colloidal particles on a SiO2/Si substrate. Nanocrystals of the Fe3-xCoxO4 exhibited bifurcation of the zero-field-cooled and field-cooled magnetizations at 300 K. The Fe3-xCoxO4 nanocrystal drop-cast films demonstrated nonlinear current-voltage characteristics between the source and drain electrodes in magnetic fields of zero and 0.2 T, and magnetoresistance reached into −46% for the x = 0 film and −50% for both the x = 0.1 and 0.3 films at 300 K. Oleic acid coated Fe3-xCoxO4 (x = 0.1 and 0.3) nanocrystal would boost developments of a high performance current switching device using negative magnetoresistance
Composition and structure of Pd nanoclusters in SiO thin film
The nucleation, distribution, composition and structure of Pd nanocrystals in
SiO multilayers containing Ge, Si, and Pd are studied using High Resolution
Transmission Electron Microscopy (HRTEM) and X-ray Photoelectron Spectroscopy
(XPS), before and after heat treatment. The Pd nanocrystals in the as deposited
sample seem to be capped by a layer of PdO. A 1-2 eV shift in binding
energy was found for the Pd-3d XPS peak, due to initial state Pd to O charge
transfer in this layer. The heat treatment results in a decomposition of PdO
and Pd into pure Pd nanocrystals and SiO
Response to "Comment on `Quantum-confinement effects on the optical and dielectric properties for mesocrystals of BaTiO3 and SrBi2Ta2O9\u27"
In this reply, the authors show that the argument by Scott regarding the band gap of bulk SrBi2Ta2O9 (SBT) is not based on concrete evidence. The authors will also show additional data from a Raman study of a powdered SBT sample to prove that the surface of the specimen was not covered by Bi2O3
Magnetoresistance of Drop-Cast Film of Cobalt-Substituted Magnetite Nanocrystals
An oleic acid-coated Fe2.7Co0.3O4 nanocrystal (NC) self-assembled film was fabricated via drop casting of colloidal particles onto a three-terminal electrode/MgO substrate. The film exhibited a large coercivity (1620 Oe) and bifurcation of the zero-field-cooled and field-cooled magnetizations at 300 K. At 10 K, the film exhibited both a Coulomb blockade due to single electron charging as well as a magnetoresistance of ∼−80% due to spin-dependent electron tunneling. At 300 K, the film also showed a magnetoresistance of ∼−80% due to hopping of spin-polarized electrons. Enhanced magnetic coupling between adjacent NCs and the large coercivity resulted in a large spin-polarized current flow even at 300 K
Response to "Comment on `Quantum-confinement effects on the optical and dielectric properties for mesocrystals of BaTiO3 and SrBi2Ta2O9
In this reply, the authors show that the argument by Scott regarding the band gap of bulk SrBi2Ta2O9 (SBT) is not based on concrete evidence. The authors will also show additional data from a Raman study of a powdered SBT sample to prove that the surface of the specimen was not covered by Bi2O3
Large frequency dependence of lowered maximum dielectric constant temperature of LiTaO3 nanocrystals dispersed in mesoporous silicate
A large frequency dependence of the maximum dielectric constant temperature was observed for LiTaO3 nanocrystals (the diameter 20 Å) dispersed in mesoporous silicate. At the applied field frequency of 100 kHz, the maximum temperatures in the real and imaginary parts were 365 and 345 °C, respectively. The maximum temperature in the real part is apparently lower than the paraelectric–ferroelectric transition temperature (645 °C) of bulk LiTaO3. The maximum temperature in the imaginary part rose from 285 to 420 °C with increasing frequency from 10 to 1000 kHz. Since the bulk LiTaO3 shows no relaxor behavior, such superparaelectric behavior is obviously a consequence of nanominiaturization of LiTaO3 crystal and insignificant cooperative interactions between the nanoparticles
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